Rangefinder wide angle lenses on A7 cameras: problems and solutions


rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
Close up lenses of different strength

In case you have read some of our reviews covering rangefinder wide angle lenses on this very blog you already know there are some limitations to be aware of and you might have also heard of the “Kolari”thin filter mod as a solution. But now, thanks to Fred Miranda forum member HaruhikoT, there is another way to use rangefinder wide angle lenses up to their full potential on A7 series cameras.
Update February 2023: guide to remove the shims on Voigtländer VM 35mm 1.7 Ultron added thanks to reader zhulinke + general update


Most of the work here was done by HaruhikoT, who allowed me to use his photos and data for this post. He shared his incredible work for free and has no ambitions making any money with it, so we decided to not even use any kind of affiliate links in this article. We just want to spread the word and give fellow photographers around the globe the option to easily use their legacy rangefinder wide angle lenses up to their full potential. In case you are new to this topic I have again summarized the problems that might occur in the following section.

Problems when using rangefinder wide angle lenses on A7 series cameras

There are quite significant differences between the different A7 cameras, or, to be precise, between the different sensors in the A7 cameras. But let’s first recap, which problems might occur:

  1. color cast on the edges and in the corners
  2. increased vignetting
  3. “corner smearing”

Color cast and vignetting are mainly influenced by the sensor design. The A7r is the worst, the A7s(II) with its big pixels and the later models with BSI sensor fare much better. One also has to take into consideration that symmetrical wide angle lenses have quite  strong vignetting by design and, in this regard, are inferior to the retrofocus designs which are mainly used in SLR wide angle lenses. Still, even on A7s and A7rII you can see a color cast with certain lenses and stopping the lens down won’t help here, as can be seen in this example:

jupiter-12 35mm 2.8 sony a7s sony-emount color cast
Sony A7s | Jupiter-12 35mm 2.8 | f/11 | color cast | full resolution

There are options to correct this color cast, I discussed some of them in detail in this article.

Sony A7s | Voigtländer VM 28mm 2.0 Ultron

The corner smearing on the other hand happens mainly due to the thick (in comparison to the Leica M cameras and especially film, where there is none) filter stack in front of the sensor. The glass is so thick that – in conjunction with the very steep light incidence of some wide angle lenses – it affects the light rays hitting the sensor. In my experience the difference between all the A7 cameras is negligible here.
There is also a reason I don’t like the term “corner smearing” : what actually happens with many lenses is that the corners are just in a different plane of focus than the center portion of the frame and naturally this problem goes away when stopping down. This leads to two unfortunate causes: degraded across the frame sharpness:

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint

And also somewhat undesirable rendering of the bokeh. While in the center of the frame everything is alright the blur lessens towards the borders. Have a look at the tree branches on the left, where the one towards the border looks less out of focus. Same goes for the bridge on the right, whereas here the effect is even stronger, as the right part of the bridge is in fact also closer to the camera. This may only happen at certain focus distances. And is less of a problem with the subject close to the camera.

zeiss distagon 35mm 1.5 zm t* adapter leica m a7rII a7r a7s a7 sony review loca ca chromatic aberration aberrations
Sony A7rII | Zeiss ZM 35mm 1.4 T* Distagon | f/1.4 | full resolution

The thick filter stack introduces additional field curvature. The negative effect of this field curvature on bokeh rendering is also explained in greater detail in this article.

Solution 1: Clever positioning of focus plane

Without any modifications to the camera or the lens (which we will talk about in the following sections) there is still something that can be done. The following portion is taken from my Zeiss ZM 35mm 1.4 T* Distagon review.

With a huge field curvature it makes a big difference whether you are focusing for the center of the frame or for the corners as you have already seen in the last section. If you want to get best across the frame sharpness neither is the optimal solution, so let me explain, how to achieve optimal focus here.

Let us imagine you are shooting a flat subject at infinity (a city from far away or some landscape) at f/1.4. The plane of focus is very thin and in our case it is also curved. Remember for all the following pictograms: Wherever the blue line merges with the red line our subject is in focus.

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint

As you can see, at f/1.4 the thin curved blue line can’t merge with the thin straight red line everywhere. So we have the choice: sharp corners or sharp center, but not both at the same time.

Now we stop our lens down to f/5.6. The blue line gets considerably thicker, meaning the depth of the plane which is in focus increases significantly:

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint

But you can also see, the blue line still doesn’t merge with the red line everywhere. Bummer. The problem is, we focused wide open and the depth of the plane which is in focus increases in both directions on stopping down. Our center at infinity was already sharp at f/1.4, so do we need to extent the plane of focus beyond that? No!

So what we can (and should) do is this: stop down first and then focus. The important thing here is: we have to check the center and the corner (or border) each time we adjust the focus.

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint

So, by a clever positioning of the plane in focus you don’t need to stop down as much to get good sharpness in the center and the corners at the same time for a subject at infinity.

This solution does not work for every lens though. With many of the Biogon designs you will never get sufficiently sharp corners by stopping down. Still, with lenses like the ZM 35mm 1.4 it is possible to get decent across the frame sharpness already at f/5.6.

Solution 2: Kolari thin filter mod

Kolari Vision is able to exchange the thick filter glass in front of the sensor for a much thinner version, which will significantly improve the results you get when using rangefinder lenses. But there are also a few downsides:

  • colors will be rendered slightly different
  • a negative impact on native lenses with short distance between rear element and sensor (e.g. Loxia 21mm) is very likely
  • you void the manufacturers warranty
  • if you change your camera you will have to go through the process again
  • for people who do not live in the US (or Canada) the whole replacement procedure is a customs nightmare and even more expensive

Still, if you already own many rangefinder lenses – and don’t plan on buying native lenses instead – this might be the best solution for you. We have a very in-depth review of the Kolari Filter Mod with many tests for more information.

Solution 3: Front end filter mod

Basic principle

This solution was developed by HaruhikoT and I think only few people know this is even possible. I will try to change exactly that.

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
Sony A7 with Contax G Biogon 21mm 2.8 and 1.5m Plano Convex Front Filter ©HaruhikoT

The idea is to use a front end filter that will reduce the astigmatism and the field curvature that comes with it. There are only a few lenses the optimal front filter solution has already been found yet, but among them are the Contax G Biogons that are otherwise of less use on digital cameras. To show you what a front end filter can do here is an example showing the Contax G 21mm 2.8 Biogon with and without filter:

Sony A7II | Contax-G 28mm 2.8 Biogon ©HaruhikoT

While you can already see the difference at this size the 100% crop offers what was  actually achieved here:

Sony A7II | Contax-G 28mm 2.8 Biogon ©HaruhikoT

You can find many more of these comparisons on HaruhikoT’s flickr stream.

But also with this solution there is a downside: with stronger correction lenses it might not be possible to still focus at infinity. With the aforementioned Contax G lenses this is not much of a problem, as they focus well past infinity. This is not true for Zeiss ZM and certain other manual rangefinder lenses.
To solve this problem you can either use an adapter that is a little too short (this is true for my cheap Fotodiox (not pro) LM to NEX adapter and also HaruhikoT’s Pixco L/M-Nex Adapter) or remove shims inside the lens (this will void your warranty on the lens of course).
Furthermore the distortion characteristics might also change with the use of an additional glass element in front of the lens.
A word of caution: you should only open your lens in case you know exactly what you are doing! We won’t take any responsibility for damaged lenses or other problems that might occur!
Fred Miranda forum member candreyo has already posted a video on how to remove the shims in ZM lenses.

Optimal filter for certain lenses

The information I list here derived from this thread on the Fred Miranda forum and is based on the findings of members HaruhikoT and candreyo.

There are two manufacturers for Plano-Convex filters: Opto Sigma from Japan and Eksma Optics from Lithuania.
For the Opto Sigma filters the exact product code is given (like: SLB-50-1500PM, the “M” and the end means it is coated, you want that).
Opto Sigma has different distributors all around the globe and they will forward you to whoever is responsible for your country. Delivery time is up to two months.
Most of the filters mentioned here are from Opto Sigma.

Eksma Optics is another manufacturer, I bought and tested a 5m PCX filter manufactured by them myself. They are thicker than the corresponding Opto Sigma filters and on the ZM 35mm 1.4 I wasn’t so happy with it, as it lead to visibly decreased sharpness in the midfield (see this chart).
Used with the VM 35mm 1.7 on the other hand it looks very good, as can be seen here.
Most uncoated filters are in stock and will be sent on short notice, if you want to add a coating to your lens (Coating number 3217-i0 400-700nm is the one you want) expect a delivery time of about 5 weeks.

I recommend getting only filters with coating, here is what happened with an uncoated Eksma Optics 5m filter to me: reflections and ghosts.

So far I can also only recommend buying the lenses marked as “Tested“.

Contax G 21mm 2.8 Biogon

Front end filter: Opto Sigma SLB-50-1500PM (plano convex 1.5m) reversed (bulbous part of the glass element shows to the lens) Tested

Infinity focus with Techart AF adapter is sustained.
See comparison above or this post.

Voigtlander 25mm 4.0 Snapshot Skopar

Front end filter: Opto Sigma SLB-50-1200PM (plano convex 1.2m) Tested

For infinity focus a shorter adapter and/or the removal of shims is necessary (I don’t know if removing shims is possible with this lens).
f/8.0 with filter / without filter

Zeiss ZM 25mm 2.8 Biogon

Front end filter: Zeiss Proxar 1m (B57 Ø50mm) Tested
Or: Opto Sigma SLB-50-2500PM (plano convex 2.5m) Tested

For infinity focus a shorter adapter and/or the removal of shims is necessary.
For further information on improvements with 1m Proxar see this post.
For further information on improvements with 2.5m PCX see this post.

Contax G 28mm 2.8 Biogon

Front end filter: Opto Sigma SLB-50-1500PM (plano convex 1.5m) reversed (bulbous part of the glass element shows to the lens) Tested

Infinity focus with Techart AF adapter is sustained.
For further information see this post.
And another comparsion with filter/without filter.

Zeiss ZM 28mm 2.8 Biogon

Front end filter: Opto Sigma SLB-50-1500PM (plano convex 1.5m) Tested

For infinity focus a shorter adapter and/or the removal of shims is necessary.
See this album  link is unfortunately dead

Leica Summilux 35mm 1.4 Asph (non FLE)

Front end filter: Opto Sigma SLB-50-5000PM (plano convex 5.0m) Tested (be aware of midzone dip at wider apertures)

For infinity focus a shorter adapter and/or the removal of shims is necessary (I don’t know if removing shims is possible with this lens).
See this post for a with/without filter comparison.

Leica Summilux 35mm 1.4 FLE Asph

Front end filter: Opto Sigma SLB-50-5000PM (plano convex 5.0m) Tested but improvements not as big as with the other lenses mentioned here

For infinity focus a shorter adapter and/or the removal of shims is necessary (I don’t know if removing shims is possible with this lens).
See this article for a with/without filter comparison.

Zeiss ZM 35mm 1.4 Distagon

Front end filter: Opto Sigma SLB-50-5000PM (plano convex 5.0m) Tested (be aware of midzone dip below f/2.8)

For infinity focus a shorter adapter and/or the removal of shims is necessary.
See this album on how to remove the shims.
See this article for a with/without filter comparison.
You can find a distorion correction profile for Lightroom for lens with Opto Sigma 5m lens mounted here.

Voigtlander VM 35mm 1.7 Ultron

Front end filter: Eksma Optics 5m Filter “110-0555E F=5000mm CT=5 mm ET=4,9 mm Ø50.8mm” (plano convex 5.0m) Tested
Or Opto Sigma SLB-50-5000PM (plano convex 5.0m)  Tested

For infinity focus a shorter adapter and/or the removal of shims is necessary. For me this adapter worked.
See this album on how to remove the shims.
See this shot for a with/without filter comparison.

Contax G 45mm 2.0

Front end filter: Eksma Optics 5m Filter “110-0555E F=5000mm CT=5 mm ET=4,9 mm Ø50.8mm” (plano convex 5.0m)
Tested but improvements not as big as with the other lenses mentioned here

See this post for a with/without filter comparison.

Voigtlander VM 50mm 1.5 Nokton

Front end filter: Eksma Optics 5m Filter “110-0555E F=5000mm CT=5 mm ET=4,9 mm Ø50.8mm” (plano convex 5.0m)
Tested but improvements not as big as with the other lenses mentioned here, loss of sharpness in midframe at wider apertures

For infinity focus a significantly shorter adapter is necessary (I don’t know if removing shims is possible with this lens).
You can find a with/without filter comparison here.

How to attach a bare glass element to your lens

Some of the Proxar lenses come with a threaded ring, so you can easily use a step up ring.
The plano convex lenses from Opto Sigma come as bare glass elements, but you can use a combination of step up and step down rings to hold them in place.
It is crucial the filters are perfectly aligned! You can use tape or small rubber bands (~50mm diameter and 1mm thick) to align the lens in the step down ring.

Here I provide a step-by-step guide which can be used for many lenses.

Contax G 21mm 2.8 Biogon

Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring from AmazonBasics 52mm UV filter (you need a camera spanner to dismantle it).

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
Sony A7 with Contax G Biogon 21mm 2.8 and 1.5m Plano Convex Front Filter ©HaruhikoT

Contax G 28mm 2.8 Biogon

Attach 46-55mm step up, 55-52mm step down, put the 1.5m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
Sony A7 with Contax G Biogon 28mm 2.8 and 1.5m Plano Convex Front Filter ©HaruhikoT

Zeiss ZM 35mm 1.4 Distagon

rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
49 ->55mm Step up ring, PCX 5m glass element, 55 -> 52mm Step down ring and part from AmazonBasics 52mm UV filter ©HaruhikoT
rangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogonrangefinder leica m lenses focus field curvature thick sensor stack optimal focus guide tips tricks hint contax g zeiss biogon
Zeiss ZM 35mm 1.4 with mounted 5m glass element ©HaruhikoT

Voigtlander VM 35mm 1.7 Ultron

See ZM 35mm 1.4 and get a 46->55mm Step-Up ring instead.
You can also take a look at this album for further information.


The front end filter solution is quite new and also comes with it’s limitations but I think it is nevertheless a great option for some lenses to be used on A7 cameras up to their full potential. I hope together we can find the optimal front filter solution for many more lenses and in case you have any knowledge to share I would love to see this list growing with it, so you are welcome to share your findings in the comment section or the corresponding thread over at Fred Miranda!

Further Reading

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My name is Bastian and I am your expert here when it comes to ultra wide angle lenses, super fast portrait lenses (ranging from a 50mm f/0.95 to a 200mm f/1.8) and I also have reviewed way too many 35mm lenses. Don't ask me anything about macro or wildlife shooting though.

215 thoughts on “Rangefinder wide angle lenses on A7 cameras: problems and solutions”

    1. If I weren’t using the Loxia 21mm already I might have also tried getting a G21mm 2.8 while the prices are still rather low.
      The increase in performance is substantial, bringing this lens up from hardly usable to quite good (at least).
      I can also see the Contax G lenses as a whole getting more popular.
      28mm 2.8 and 90mm 2.8 make a very nice and small 2 lens kit with more than decent image quality.

      1. But they still have their odd focusing mechanism via adapter. But alone for all M mount lenses from Leica, Zeiss and Voigtländer is worth it.

        1. Contax G 90mm: Must say I’m quit happy with the Fotodiox Contax (g) NEX adapter and very impressed by the IQ of this little gem, even at f2.8.
          Adapter see: http://www.fredmiranda.com/forum/topic/1316063
          Not so happy with the AF version ( Techart) for this lens. TheThe Teacart is Okey with the 35 and 45mm.
          You won’t do super tracking focusing but good enough for normal moving subjects.
          Very good manual control focus. But if you buy an adapter it’s maybe easier buy one for each Contax G lens in your possession, not so easy to do the change when you’re in a hurry.

          1. I have the same adapter and focusing is quite easy for me and smooth, i did a little bit extra lubrication with lithium grease after some weeks of use and i have no problems to swatch lenses, but i had to treat reflections inside the adapter with velour foil (better with blackboard color) for my G90mm 2.8 so the contrast is much better if you shoot against bright light
            i will order the Planoconvex lens 5m to test performance on G45mm

            Bastian:…..thanks for the great work you do

          2. Please share your experience with the 5m lens on the G45!
            No one did before and I would love to include if after someone has tested it!

          3. Some of the Contax G to E-mount adapters are really, really touchy about mechanical fit with the lens. The Techart v3 less so. You can leave it on the camera body and change G-mount lenses without undue drama.

            @BastianK, thanks so much for all the good work!

      2. i’v tested the G21,it performs impressive.
        i also have a voigtlander 21 F1.8 VM on hand.
        the G21 80% frame is really sharp wide open, the rest 20% get very soft dramatically, ceter almost get peak sharpness wide open. F4 gets peak. in the 80%area, the VM need to get F5.6 still a little bit softer than G21!!! at F8 only a few pix about a 1:1 zoom area gets soft, but never gets better…at F8 the sharpness soft corner probably equal to VM21 F4-5.6.
        and the CA always much better than VM21.
        but at F8 the best aperture, the VM21 a little little bit sharper than G21 all cross the frame.
        BTW, it’s 150 grams weight!!!! even 250 grams lighter than loxia! if you grab G21 G45 G90 for days backpack trekking, probably they are the lightest kit you can choose, the loxia21 50 85 are 700grams heavier than contax G kit!

  1. So, these filter eliminate the field curvature or only corner smearing? The later would mean, the corners are still out of focus but not smeared.

    In general a great idea. Maybe some Chinese manufacturer cover up this story and bring out some dedicated filters for these lenses. The market for adapting lenses to A7 bodies is quite big.

    1. I don’t want (and maybe I also can’t) delve to far into the subject here and instead just answer your question by saying: eliminates the field curvature 🙂

      1. As someone sitting on two examples (sigh…) of the 28mm Biogon (G1 & G2, also), I wish to thank you so much, Bastian, for addressing that important distinction… and succinctly! I am similarly curious to know if the supplementary lens approach also flattens the field of focus on the 45mm Planar G without notable penalty?!

        THEN, leaving aside the discussed lens handling concerns, there remains the big question as yet largely unanswered : How do these DIY augmented C-Z G lenses, including, as well, the 21mm Biogon, finally stack up as all-’rounders for image quality on the sorts of subjects featured here… vs. the alternatives already reviewed on this site?

        At just the 28mm FL and near it, I have on hand already a “beastiary” of circa 28’s: the 25mm/2.8 Zeiss ZS… SMC Pentax f.3.5… Nikkor AI f.2.0… Olympus OM Zuiko f.2.0 MC… Konica AR f.3.5 7-element… the favored iteration [out of 28?!] of the Vivitar f.2.8 K-mount… Canon EF 2.8 IS USM… and a most-likely-to-sell-on, Sony FE 2.0 (in favor of the less tricked out & image stabilized Canon).

        SO… my question is, after ‘cleaning house’ a bit at the circa 28mm FL, where could I expect the DIY modified Biogon to fit into this picture for IQ on landscape/cityscape/& nature subjects? What do folks think… is it still a keeper among options I might retain?

        Thanks, Bastian, et.al. …[and BTW, I think of this FL, as it pertains to the vintage glass, as a logical one among the possible “landscape” FOV options in which to assemble a small collection of different ‘renderings’ at a justifiable cost; which I hope explains the seeming extravagance of having so many ‘testers’ here for the time being. Feeling a little self-conscious… ?]

  2. Rather impressed by the mailings around this topic since a while. Maybe in the future we will find photographers with their stuff in the ophthalmologist waiting room 🙂
    Serious now, the idea is rather incredible nice, finally a solution to deal with the “legacy normal to wide angles” on the A7 series.
    Would be nice to have some kind of simple list with the already existing proposed filter solutions.
    And “reinhard” made the same bad decision to send the 21mm back… 🙁

    1. What you see in this article actually is the “simple list with the already existing proposed filter solutions”.
      If you know of any else I would gladly add them.

  3. Yeah would be great, Think the simulations could be tested by someone who is in possession of both.
    Have the lenses but was hesitating about buying the filter(s). Happy about the performance from f5.6 so didn’t go for it until now because ( a lot of landscaping for the moment)

  4. I strongly agree with Edwards comments on the Fotodiox (pro) adapter. Focussing works very well, but changing the adapter is a nightmare. I use it only with the Contax G 2.8/90, so I have no

    1. Have either you, Joachim, or Edward above used the Metabones adapter for Contax G? I’ve had one somewhere in a drawer for a few years (very good price on auction); and now I am curious about this Fotodiox option, having just acquired an A7 II, soon to arrive. The Metabones is a bit large and inelegant, but seems sensible enough in principle, at least so far as leverage for focusing goes. There are 28mm, 45mm, & 90mm G lenses already here with my G1. Thanks.

  5. Danke für diesen schönen und wieder sehr aufschlussreichen Artikel!

    Er ist übrigens nicht nur für Altglas hilfreich: auch einige ganz moderne Objektive zeigen u.U. Bildfeldwölbung (z.B. das Sony FE 70–200mmm f/4.0 um die 100mm herum, zumindest mein Exemplar), und auch da ist die Technik anwendbar, die Ihr unter „Solution 1: Clever positioning of focus plane“ so anschaulich beschreibt. Danke!

  6. I ordered an SLB-50-1500PM lens from Opto Sigma (US) and when they called me to confirm the order, they asked “oh, is this about those Sony camera blogs?” 🙂 BTW, quoted delivery time is ~5 weeks.

  7. Thanks for your excellent work with this blog and all the wonderful pictures. As a steady reader who is not only taking pictures with a Sony A7 and mainly manual lenses but is also interested in technical matters this article is a particular highlight to me. With solution 3 I will now revive all my Contax G-Lenses. The Contax G 90mm f2,8 is aready in my everyday camera bag accompanied by the Sony Zeiss FE 2,8/35mm. My modest collection of about 60 lenses (most of them old Canon FDs) is not meant for a crystal cabinet but for regular use.

    1. If I wasn’t using the spectacular Loxia 21mm 2.8 already I would definetly try the Contax G 21mm 2.8 with such a filter.
      So you are heartily invited to share your results!

      1. I’m still waiting for two of the Opto Sigma lenses. I ordered the OSE-SLB-50-1500P (28 €) and the OSE-SLB-50-5000PM (58 €) to use them with my Contax Zeiss G21, G28 and G45. First Problem was: You can’t order the Laser Lenses as a privat person. You need to order them via a registered company. Shipment will last five to six weeks and costs about 17 €, but if your total order is below 250 € you have to pay a short surcharge of 25 € as an extra. But I’m still full of expectation how they will improve the G-Lenses on my Sony A7. My CZ G 90 f2,8 – I have a black and a champagne coloured version – are already very decent performer on the A7.

      2. Thanks a lot for sharing this very elegant planoconvex additional lens solution.
        I have Contax G biogon 21 & 28mm and was very disappointed by image corner smearing. Now with the SLB-50-1500PM from OptoSigma, the results are incredibly good.
        Biogon 21mm 2.8
        compared to Hexanon 21mm 2.8 AR
        Biogon 28mm 2.8

  8. Nice work Bastian and all who are working on this projekt, do you or Phillip have the possibility to test the Voigtländer 35 1.7? Don´t have the money for the Zeiss, but would love to improve the 35 1.7.

      1. BTW, could you, Phillip, or anyone here comment why the ‘near’-35mm Voigtlander Ultron 40mm f.2.0 SL II doesn’t get more respect in these circles compared to its apparent rep with the DSLR crowd? I’m not arguing a point here — I HAVE seen some mixed opinions — but I have not read thorough or convincing comments by way of criticism. Like you, I value attractive rendering qualities … not just sharpness tests or “conventional wisdom”.

        The Ultron can be sort of wanting for smooth bokeh, but the 28mm f.2.8 Contax Zeiss MMG/MMJ seems more bothersome to me in this regard (I have the SMC Pentax [-K] 28mm f.3.5 like you, among other 28’s, BTW).

        On the other hand, the dedicated close-up lens accessory seems to work very nicely to deliver a clean 1:4 magnification without bulk — very handy, I think.

          1. True enough; but still not burdensome compared to most of Sony’s ideas about what is compatible in physical scale among their better lenses for the mirrorless bodies. And I’ll likely have the Nikon G-type adapter with me regardless, for one or two other lenses.

            I bought a secondhand Commlite adapter for Nikon to try when I can. The attraction there is: 1. Seemingly few worrisome complaints with Commlite’s low cost “AF” adapter for Canon EF… and 2. Their claim that the aperture adjustment ring is calibrated to actual f-stops… a big plus if even only somewhat true.

          2. I’ll add an edit to the foregoing: there seems to be a complaint or two regarding Commlite elsewhere in on-site “Comments”. ‘Mixed reports’ are the norm, I would say, regarding the experiences of individual users with the adapters they’ve tried [tried… maybe]. Sometimes the possibility of sample variation is cited; and sometimes not (usually followed by a sweeping generalization related to the device’s inherent suck-itude).

            I might suggest setting up a separate section on site — a database reference — for collecting all the reader reports about the reliability and effective performance of the various lens adapters on mirrorless bodies; and about trials with correction lenses, such as for Contax G to Sony FE, as well.

            I would note that if you have a “poor quality” adapter and the one you have puts your adapted lenses into proper alignment according to some sensible, measurable, objective standard… and it stays that way in use… then you have a good adapter regardless of others’ opinions (perhaps after improvement with a DIY anti-reflection modification). There are surely ways to “lock in” that performance, once achieved. At that point, wisdom may come down to “If it ain’t broke, don’t fix it”. Thanks and good luck everyone.

  9. What a fascinating development. Kind of sad I sold my Contax G collection. I loved my 28 but the corner issues made using it a crap shoot. My FE 28mm is great, probably as detailed, but seems to lack some of the rendering and character.

    This also rekindles my interest in seeing more new symmetrical lens designs (with equivalent built in elements) for FE mount. I’d assumed, like many people, that a biogon wider than 35mm couldn’t be done but clearly that isn’t the case!

    1. If there is anyone interested in more small yet capable modern lenses it is me ☺
      I think Voigtlander might have something in store for us in the future.

      1. Bastian, have you made any progress finding an HD DA Pentax 35mm f.2.8 macro to test on your Sony (following on from your problematical experience with the *nominally* sibling Tokina Pro 35mm macro)? I can assure you, I think, that the coatings — and design spec? — on the Pentax iteration make this one an entirely different thing when it comes to usability. There are shots of both the older SMC version (cheap now, if you’re patient) and the HD version shot directly into glare-y street lighting at night on the pentaxforums website (tested on introduction of the revised versions by Adam and the staff). The older one was good… and the newer may be the most significant of the HD revision upgrades.

        I just picked up a Sony A7 II last evening after having lost access to an A7 for quite some time; so I haven’t had a way to test my own (auction bargain) HD DA 35mm macro on full frame directly. The Pentax is decent enough to focus manually (not sloppy, being precision geared screw drive for AF) and is reported to be alright on a FF sensor at infinity focus at a 1.10-1.15x crop — not the end of the world, particularly for those with A7R II’s. Not that many small, finely crafted 35mm lenses out there as candidates for sensor stack compatibility…

        1. I couldn’t really find a decent Pentax -> E-Mount adapter with aperture control mechanism so therefore kinda halted that investigation. But by now I also think regarding performance against bright light the SMC version is better and the HD even more so.

          1. Yep, that’s a question. In my case, and at my age, I’d go the extra mile to arrange for having cross compatibility and some strong AF options at a few most broadly usable FL’s between A7 II/A5000/Canon M3 (or ?) on one hand; and the Pentax K-1, probably in my future, on the other. Thanks!

  10. Bastian – I would like to try this with my Zeiss Distagon 35/1.4ZM. But I’m not sure I want to mess with the shims. You mention that the alternative is to find a slightly shorter adapter. Has anyone found an adapter that meets this spec or is it more trial and error?

    Thanks for the great article!

    1. Dear Bob,
      I found this adapter to be short enough to reach
      infinity with the ZM35mm 1.4 with mounted 5m filter without having to adjust the shims.
      I bought mine a few months ago, so I don’t know if they have adjusted the thickness,
      but judging the comments on Amazon: I don’t think so 🙂

  11. Hola, me encanta tu blog, te leo seguido pero nunca me habia animado a comentar, queria decirte que tu sitio es genial y que esta nota me ha gustado mucho, continúa así, estoy suscrito a tu sitio desde el rss, gracias 😀

  12. Theoretically could this work as well on the Zeiss 35ZM 1.4 , if the PCX 5m glass element was custom cut to to fit into one filter? ie for a clean straight forward 1x filter fitted 5m solution for 49mm ?
    Potentially big possibilities here for some of the filter manufacturers if I understand it the physics should still work – albeit in a more convenient + simpler 1 filter adapted product if possible ?

    1. It should work, yes.
      Regarding filter manufactures: the problem is you have to adjust shims or use a shorter adapter,
      so they can’t really sell you a “all in one” solution.
      I also think using RF lenses on A7 cameras is more of a niche thing, so I doubt it would be worthwhile for a manufacturer in the long run.

  13. Hi Phillip,

    I am interested in ordering the Eksma Optics filter as recommended for Voigtlander VM 35mm 1.7 Ultron.

    Do you know if Techart Pro can focus to infinity?

    Thanks in advance.

      1. Thanks for the reply.

        Got the quote from Eksma Optics – 220 EUR delivered for the coated convex filter – Ouch!

        That’s quite an investment….

    1. It’s been a few years but I thought I’d provide an answer here in case anyone else is looking – the Fotodiox Pronto Pro Mk II AF adapter will focus at infinity with the 35mm f1.7 Ultron LTM and a 5m pcx filter. In fact even a little beyond, so probably the VM mount 35/1.7 ultron will also.

  14. OK, after a 5 week wait, I have the Opto Sigma filter. Attached to my 28mm Contax-G Biogon using the 3-step up ring method described above. I use an A7ii body with TechArt “Golden Eagle” G to E-mount autofocus adapter.

    + This combo delivers fabulous edge to edge sharpness for interiors, with minimal vignetting. PD autofocus works great.

    – This combo does not focus to infinity and any subject beyond about 10 meters is out of focus. PD autofocus hunts unsuccessfully and manual focus does not help.

    Any thoughts on a focusing fix? Preferably non-destructive? I still have a Contax G2 body and shoot film occasionally. Results are still very good, this was a primo film camera in its day.

    1. This is unfortunate to hear.
      As I don´t have this lens or any Contax-G adapter I can only recommend contacting HaruhikoT directly through the FM forum as he was using this combination with success.
      Other people are using a Kipon adapter and also had no issues focusing at (and even beyond) infinity (check the links I provided).

    2. Hi Andy

      My contax G28 + Optosigma 1.5m reach infinity with the techart Golden Eagle adapter.
      Perhaps copy-to-copy variation of those adapter and the lens cause the infinity issue.
      There are two possible solutions for you.

      1. Try Kipon MF adapter
      Some cheap MF adapters are known to have enough margin to exceed infinity.
      FM forum admin Fred recently managed to reach infinity with unmodified G Biogon 28 + Optosigma 1.5m + Kipon MF adapter:

      2. Remove shims
      You can adjust infinity by removing your G Biogon 28’s internal shims. This is non-destructive modification.
      Rotate front name plate using a rubber lens opener, remove 4 screws under the name plate then you can access the shims.
      Sebboh’s post in FM forum should be informative, the 4th image shows a gold shim:
      My concern is, however, perhaps removing shim affects rangefinder AF function/precision when you use it on original Contax G2 body.
      I don’t own G2 so not sure about this.

      1. Hi,
        Your summary states the infinity focus with Techart GA3 and PCX 1500 filter is retained with both Contax G Biogon 28 mm and Contax G Biogon 21mm.
        I have both lenses now and neither of them can be focused to infinity with my copy of the Techart Adapter, even after removing the shim.
        No problem with the manual adpaters though.
        It appears the Techart adapter limits the number of revolutions of the screw drive.

        1. There seems to be a fairly large variation in the infinity position of the Contax G wides themselves. I designed my conversion rings to leave one full millimeter of slack to focus past infinity with the first Contax G 21/2.8 I converted. Since then I’ve converted 3 more and 2 of them could not reach infinity (even with all shims removed) except on a short m-mount adapter. I have to make a new batch of conversion rings for them.

  15. Haru and Bastian, thanks for the quick replies. I will try the cheap adapter route since removing the shims may cause problems with my antique but still fully functional film camera. BTW, I would definitely believe sample to sample variation in the Techart adapter, which is (was?) a definite niche product.

  16. Thanks for all this information and testing Bastian (and Haruhiko). Here are my experiences concerning adapters and reaching infinity at each lens’ largest aperture. The Ulata adapter focuses (far) beyond infinity for all Contax G lenses I tried. Interestingly, I could not reach infinity for the VC35 using the recommend Fotodiox adapter (only my Techart was able to do so).

    G21 and Opto Sigma SLB-50-1500PM:
    Techart TA-GA3: No
    Ulata: Yes
    Note: For the Ulata the lock pin on my copy had to be filed down a tiny amount to clear the rear lens guard.

    G28 and Opto Sigma SLB-50-1500PM:
    Techart TA-GA3: No
    Ulata: Yes

    G45 and Opto Sigma SLB-50-5000PM:
    Techart TA-GA3: Yes
    Ulata: Yes

    VC35 and Opto Sigma SLB-50-5000PM :
    Voigtlander VM Adapter (Ver 1): No
    Fotodiox (Recommended by BastianK): No
    Leinox (cheap and flimsy): No
    Techart LM-EA7: Yes

      1. Yes. Fortunately, they are not that expensive 🙂

        I have lately done two attempts to test the G45 with the SLB-50-5000PM filter:


        I have not studied the results too closely yet. There seems to maybe be a very small corner improvement from f/2 to approximately f/5.6, but it is nothing spectacular as opposed to the G21/G28. Any comments are welcome.

        I think this filter most likely will be permanent on my VC35 instead.

    1. Hi,

      You mentioned that you were able to achieve infinity focus with TAP + CV 35/1.7 with filter. May I know where your infinity focus point is on the TAP without the PCX filter? I’m trying to figure out if mine is able to reach infinity before purchasing the filter; currently, infinity for me is somewhere just before the middle of the infinity symbol.

      If anyone else is able to achieve infinity with the CV 35/1.7 and the TAP, please do chime in!

    2. Hi all, Thanks to your great informations,
      Can you tell me if I need to cut rear flange of Contax G21 to put it in a Sony A7II thru a Techart III Adapter?
      I read some contradictory information about this.
      Thanks in advance,

        1. I used the Contax G 21/2.8 on a techart AF adapter in 2013 with no problems from the lens feet. It’s possible the adapter design has changed slightly since then (I haven’t been following iterations closely). The lens feet definitely do not interfere with A7 cameras though on other adapters (I had one on a few days ago). Looking at pictures of the adapter it looks like the feet should just fit through without hitting the flat internal part of the adapter, but I can’t tell for sure from the picture. The feet on the Contax G 28 are almost identical in size and it works fine (just a little shorter). Many people have difficulty with Contax G adapters because they are expecting the whole lens to rotate when mounting rather just the part where a focus ring would be. I can imagine people trying to make the whole lens rotate to mount on the adapter and concluding erroneously that the feet were blocking it from turning when they were really just not trying to turn the correct part of the lens.

          1. Thank you very much.
            Another issue, if you could be so kind… :
            The techart adapter in my Sony A7ii only works properly in contrast detect Autofocus, but I saw a youtube video where the AF performance in Phase Detection mode (in a A7ii also) would be much better. But when I change to Phase detect AF the adapter doesn’t work unless it is in F22 (I thought it would work better wide open). Do you think that it could be a problem of the adapter? I was told that it was in the last version…
            Thanks in advance,

          2. I’m afraid I can’t help you there. It’s been a while since I used the adapter and I just had the owner set it up for me. I pretty much immediately had it switched to manual focus after a few tests to see the focus speed (I’m not much for AF).

  17. I have so far managed to say to myself what my favourite lenses are in the areas of 45-55mm, 85-100mm and 135mm focal lengths for my Sony a7S2. However, I have had difficulty in the areas of 21-35mm. Especially, I have tried quite a few models I short-listed, but I am yet to encounter something I want to keep in my camera gear for any occasion. Then, I landed on this webpage. This made me long more for “Voigtlander VM 35mm 1.7 Ultron” in Sony FE-mount.

  18. Although the subject of lens filters has not tickled my penchant yet, but I just use protector, UV or POL filters only, I must say I liked the story behind the way this article came out as mentioned in the Disclosure section.

  19. Dear Bastian,

    I am Ali, technical support at Optosigma Europe.
    We are glad to see one of our customer using as wisely one of our product.

    We want to thank you for the promotion you make of our product.

    Know that we stay at your entire disposal if you need anything, feel free to contact us at :

    I wish you a lovely day.
    Best regards
    Ali ANOUAR

  20. Hey,
    thanks a lot for explaining the Sony wide-angle problem and possible fixes for it, in such a detailed way. I got two questions regarding the front end filter mod of the 35mm Ultron from Voigtländer:
    Apparently you tested both lens manufactures (Eksma Optics and Opto Sigma), which do you prefer? (based on your comparison chart i have a hard time to judge)
    What manufacturer/model of step-up, step-down and UV-Filter did you use, that worked for the mod? (i live in europe as well, so we might have the same shopping possibilities)
    Thanks a lot,

    1. Dear Benjamin,
      the differences between the Eksma and Optosigma lenses are rather small with the VM35 1.7.
      I am currently using the VM 35mm 1.7 with the Optosigma lens and I am quite happy with the results.
      I tend to recommend the Optosigma lens as it is thinner and cheaper with coating.

      I was using the following rings and tools:
      46->55 Step Up ring: http://amzn.to/2okqCNl
      55->52 Step Down ring: http://amzn.to/2oJrege
      Rubber ring to center the filter glass: http://amzn.to/2okksg5
      Retention ring from 52mm UV filter to clamp the filter glass: http://amzn.to/2oJvj4a
      Camera spanner to remove retention ring from UV filter: http://amzn.to/2oIOqgb

      1. Eksma was quick to reply. They sent me two specs and i got confused on which to use:

        1. BK7 pl/cx lens d50.8mm F=5000mm +/-2%@546nm, both sides coated AR/AR @ 400-700nm, R<0,9% per side, AOI=0 deg

        2. BK7 pl/cx lens d50.8mm F=5000mm +/-2%@546nm, both sides coated AR/AR @ 400-700nm, R<1,8% per side, AOI=45 deg

        The difference is in the coating, but have no idea which to chosse. Can you help? 🙂

      2. Bastian, do you know if there is also any coated UV retention ring available? The one you listed seems to be very simple or even uncoated, right?

        Didn’t you use a complete UV on top due to danger of vignetting?

  21. Does anyone have experience yet with the A9? Does its sensor have the same filter stack (and the same issues with adapted wide angles)?

  22. Any chance you can test the CV 21mm 1.8 Ultron and see if it’s affected by the corner smearing issue and if it is – which lens improves it?

    Would also be nice to see a review on that lens!


    1. I am pretty sure it shares these issues.
      Another problem is the non removable hood and the 58mm filter thread.
      It is quite difficult getting these filters in bigger sizes than 50mm,
      so I don’t know if it is even possible to mount one without running into major vignetting.

      Nevertheless, if I come across somebody who will borrow me his lens for a review I will gladly check 🙂

  23. Any source for ordering the

    Opto Sigma SLB-50-1500PM (plano convex 1.5m)

    as a private person in Germany ?

    1. laser2000.de has updated its online shop just recently and dropped the minium order requirement.
      Do you still need a company to order there?

  24. Bastian, thank you for this very interesting article!
    Can you confirm that the convex side of the lens / correction filter (Opto Sigma: SLB-50-5000PM) for the VM35mm f1.7 should be facing towards the outside and the flat side of the lens should be assembled towards the objective (VM35)?

    1. Dear Marco,
      this is correct, but as the correction filter is very weak there is not much loss mounting it the other way round. I barely noticed a difference.

  25. Hi Bastian,

    Sharing some info and wanting some advice… 🙂

    I have the CV 35 1.7 but the older L39 (LTM mount for leica) and bought the opto sigma lenses, rings and etc.. as you suggested, thanks! But on mounting the lenses I realized(late) that the lens tread for the LTM version is not 46mm but 39mm!! LOL

    Could I use a step up 39>46 to use on the already set opto or should i go for a 39>52? As the CV lens is 39 and Opto 50 will the correction work?

    Thanks for the excelent articles and advice.

    1. Both options should work with minimal differences.
      Nevertheless, I don’t know of anyone who has tested the older L39 version (which has completely different optics) with the OptoSigma lens.
      So you are invited to share your results 🙂

      1. I just tested the LTM version of the CV 35mm F/1.7 with the Optosigma 5M correction lens. There is some improvement in corner smearing but maybe not as much as with other lenses tested here. Here it is wide open.


        The only adapter setup I found that’s able to focus it at infinity is using it on a Fotodiox AF adapter via a LTM-M adapter ring. This works pretty well, it hits infinity and a little past, and AF even works sort of decently.

        I have the impression that even with the correction, this lens is considerably sharper in the corners on film than on the Sony.

  26. Thank you Bastian for this fantastic summary. The thread in Fred Miranda forum is also very impresive. Still, I would be interested to know your opinion. If you do not own already Contax G or ZM lenses, it is worth go for them, or even considering the difference in the amount of money, would be more logical to get a loxia?

    1. Dear Jorge,
      very good question indeed!
      Talking about the VM35mm 1.7 +5m PCX: I still use it very often and at the moment there is no better 35mm option for me (despite no less than 4 native options), regardless of price.
      Talking about ZM 25mm 2.8: the Batis 25mm 2.0 would be your native option here, but it shares few similarities with the ZM so you might prefer the ZM+filter.
      Talking about the Contax G 21mm 2.8: I think this lens does not stand a chance against the Loxia. If you can afford the 21mm Loxia by all means get it. Still, there is roughly a 1000$/€ price difference compared to the Contax and in lack of other alternatives it might be a very nice budget option.

      As you see this question is not easy to answer. But yes, in some cases it is worth buying one of these lenses with the sole intention of using them wih correction filter on an e-mount camera.

      1. Thank you Bastian for your answer, and sorry for the delay in the answer.

        Concerning ZM and Contax G systems. I understand, that at least for the wide angle lenses, they must me pretty similar optically. Mostly Biogon, and at 21mm and 28mm, contructions must be close. It is like that or I am missing something? Maybe the ZMs were actualized…

        You also mention about the vignetting of the rangefinder lenses. Is this something very anoying, or it does remain moderate? I understand from your reviews it is significantly stronger than in SLR lenses.

        Thank you very very much for your fantastic blog!


  27. Hey everybody,

    here’s my results from testing the Voigtländer Color Skopar 25mm, based on Haruhiko’s recommendation to use a 1200mm PCX lens (thanks again so much, Haruhiko!!!). Without filter the CV25 performs just horribly on the A7. With the PCX filter the lens becomes quite usable on my A7, albeit not perfect. The difference that PCX filter makes is quite impressive. (As a side note: with my Nikon AIS 24mm F2.8 I get better corners, but the center is better with CV25; also, the CV25 seems to produce nicer colors).

    These were shot with the CV25 at F8:
    With PCX: https://ibb.co/cknLt6
    Without: https://ibb.co/dHqUmR

      1. No, they’re taken at F8… I went through F4 to F22, so if you’re interested in some more test shots, let me know.

        1. Would be great if you could also upload the f/4 shots!
          Would be even greater if you could make a flickr album (or something like that) with these shots so I can place a link to it.

          Oh, and should it be mounted with bulbous part facing the lens or the subject?

          1. Here’s the album with all F-stops. The PCX performs a little bit better if the planar side faces the subject and the convex side faces the camera.


            Side note: I also bought a cheap +1 close-up filter, which didn’t perform as well as the PCX. But I ended up using the ring of the close-up filter to hold the PCX lens, which I had ground by a friendly optometrist.

  28. Hi, i have a Voigtlander 40mm 1.4 M mount on an A7rii and i experience a lot of issue with it. My main issue with it is color shift on some image, does it come from this? or is this because i use the cheap adapter ? Cheers

    1. Color shift is caused by the sensor itself, not the sensor stack or the adapter. You can use tools like cornerfix or the flat field plugin to correct it but there is no way to modify your camera to get rid of it. Some cameras like the a7riii or a7s are less critical than the a7r or a7.

      1. Do you think a plano convex 5.0m filter should help with VM 40mm f1.4 lens?
        I’m using this lens on A7III and I have to say that corners are a bit soft, even stopped down.

        1. The CV 1.4/40 is small, but IMHO that is about all there is to recommend it, even on film. Only a small area is reasonably sharp. The area grows as you stop down, but it’s never really sharp corner to corner. I can imagine someone liking it as a sort of retro effect lens, but unless that’s your goal, it’s not a great choice unless size is absolutely paramount and you also want the speed.

  29. Hi,
    concerning the Ultron 35 and the fitting adapter, for what kind of manual adapter do I have to search? Have two here where I don´t reach infinity with the unmodified Ultron, so they are too short I guess and could work with an 5m PCX? Or is it the other way around, bit confused.
    Has someone tested the Ultron with the 4m PCX so far?

    1. You need an adapter which is too short, if you can focus past infinity and something far away is sharp when your focus ring is set to 5 meters there is a good chance it will work with the 5m PCX filter.

  30. Hi Bastian,
    thanks a lot for a great article.
    Can you please giving me an advise with Voigtlander Nokton Aspherical 35mm f/1.2 II mounted on Sony A7RIII?
    I’ve purchased this lens way before reading this article and was not aware about this issue. 🙁
    Should I need some filter, and which one?
    Thanks in advance

  31. Are there any stock “short” adapters that will give infinity focus using a Contax G 28 2.8 Biogon (modified to LM mount) with the Optosigma Plano CVX BK7 D50.0/FL15 in reversed position? Works well for cleaning up corners, but I can’t reach infinity using either the TAP AF adapter (LM-EA7) or Voigtlander LM to E manual adapter.

  32. Hello,

    I have a concern about Voigtlander VM 35mm 1.7 Ultron. You mention an shorter adapter is necessary. I would like to try it with the voigtländer helicoidal adapter.

    I try the ZM 25mm and removing sims was an easy task. Do you have an idea or photos or something in order to remove sims in the VM? or it would be unnecessary with the helicoidal adapter?

    I also give look into FM forum but no info concerning this.

    Thank you very very much in advance!


    1. So far no one has found a way to make such modifications to the VM 35mm 1.7.
      The VM-E close focus helicoid adapter is too long, you won’t be able to focus past ~5m.

  33. Hello,

    trying the Opto Sigma SLB-50-5000PM with the Voigtlander VM 35mm 1.7 Ultron I discovered I cannot focus to infinity with the suggested Fotodiox adapter.

    Any other suggestion fo a short/shorter adapter?

    Best regards and help you in advance,


  34. Hi!

    I have to make filter with the Opto Sigma SLB-50-5000PM only myself? Is there some prepared items into the market? If not, where I can buy this lens, only directly from manufacturer? And what about Techart Autofocus adapter, will it suitable because of the changing wide size? For Voigtlander 35mm f1.2 II, will this Opto Sigma SLB-50-5000PM proper for this one ?

    1. I have explained in great detail how to attach the filter to a lens. You can’t buy it prepared anywhere.
      There are also links in the article where to buy it (yes, directly at manufacturer).
      With Techart AF Adapter you won’t be able to focus at infinity anymore.
      The filters are only readily available up 50mm Ø, the CV 35mm 1.2 II has a 52mm thread, so you might run into vignetting issues.
      I can’t tell you what would be the right filter for this lens.

  35. Thank you very much for your response. It’s a pity, that you can’t advise some solution for this lens! This is a good lens, but from 1,2 to 4, the edges are soft, which is not critical for portraits or subjects and too negative for widescreen photos.

  36. Hi,
    I’m buying this summer a Sony E (best choice Sony A7II), and own a beautiful Leica M 21mm 2.8 asph.
    Have you tried this lens sometimes on your Sony’s? You think I will have any trouble to adapt it to the A7?
    Thank you for all the comparisons and reviews, I’m learning a lot from this webpage.

    1. Actually, I have shot with m 21/2.8 asph, but only on a kolari UT thin filter modded sony a7, not on stock sony camera (I no longer have a stock sony). Sharpness wise the lens is extremely good on the modded sensor, better than my contax g 21/2.8 (which I love). I would imagine that it has a fair bit of corner smearing on a stock sony though. 🙁

  37. thanks you guys. For ZM 35 1.4, should I use 49-52 with the 50 diameter filter order from opto sigma directly? or I should purchase a 52 diameter one?


  38. hi Dear BastianK,

    received the filter of Opto Sigma for ZM 35 1.4 today. after put it on lens, I found it can’t focus at the infinity. I am using Techart automatic LM-EA7 adapter. Any suggestions?

    btw, which way I should mount the filter? the flat side towards camera, while the curve side towards objects, right ? have tried both way.

    1. Dear Bryan,
      I recommend to have a closer look at the article again.
      You have to remove shims inside the lens to still be able to focus at infinity.
      There is a link in the article that explains how to.
      Personally I found it made little to no difference which way you mount the filter with this combination.

      1. Thanks! got it! will try it again tomorrow.

        I feel that flat side towards camera has a little bit better result. (curve side towards outside).


  39. Thanks a lot for sharing so important details on optical correction of RF lens on A7 series. It’s so helpful! I’ll definitely give a second chance for wide angle lens like Voigtlander 28mm F2.8 or Zeiss ZM 28mm F2.8
    Currently I’m only shooting with Voigtlander 50mm F1.5 on A7S, and borders are acceptable, though it’s be nice to make them better.

    Meanwhile, I’d like to share few disassembly articles that also include steps of focus shims access for two Zeiss ZM lens:
    Zeiss ZM 50mm F2.0 Planar

    Zeiss ZM 50mm F1.5 C Sonnar

  40. First of all, thanks for the precious informations.
    I’d like to know why on C/G 21mm and C/G 28mm additional lens is clamped in two different ways: on 21mm using an empty filter, on 28mm using a step-up adapter. Apparently, there should be no reason to clamp them in the same way.
    Additional questions: should also C/G 35mm be upgraded in similar way (and with which lens)?
    Should these improvement be done also on A7III with BI sensor?

    1. There are many different possible ways to mount a filter, if you prefer one over the other and it works for you: nothing wrong with that.
      Some people tried using different filter on the C/G35, but in my memory it simply wasn’t worth it as improvements were minor.
      As is described in the article the loss of resolution towards the corners is due to the filterstack, whether the camera has BSI or not does not matter.

      1. Thanks.
        Another question. A friend of mine tried the solution on C/G 21mm, and he complains about vignetting. Does it make sense to avoid the first stepdown and use a bigger lens with same correction, or correction values should be recalculated?

          1. On our original G1/G2 the lens did not make any vignetting.
            He says me on A7II (pure) it vignettes, with the additional lens it vignettes more. So I’m asking if a larger lens would solve the problem.
            Do you know if anyone made a comparison among different adapters, in order to see if the problem arises from them?

          2. On film it will vignette less, yes.
            I doubt the the difference between with filter and without filter will be meaningful.
            If the ring was in the frame this would not mean additional vignetting but simply black corners.

    1. As I haven’t tried it myself I cannot give a definitive answer.
      I tried to include the ones which I tried myself and the ones were decent samples showing the difference were posted, but in this case maybe you have to dig through that Fredmiranda thread to see if anyone tried.

  41. Can you say where to get that rubber ring (which diameter) and the exact frame-less UV filter?

    Does the Optomsigma have to be mounted concave towards the camera or the opposite?

    1. This is the filter I am using and these are the rubber bands.
      If you are talking about the 5m filter: it doesn’t really matter which direction you mount it.
      Some people claim one or the other way is better but imho it is negligible here.

          1. Ah I see…so as the corners are soft from 2.8 to somewhere, it’s just soft in the corners for another reason

      1. What I didn’t fully understand through the different statements…did you have infinity focus in this configuration with the TAP adapter or not?

          1. Yes Bastian I didn’t want to say someone recommended the Novoflex, in opposite it was known as not working, I just wanted to describe my experience. It seems the adapters vary strongly.

          1. I have my plano config ready now and triedbit with the Voigt Ultron 35. The recommended Fotodiox and the Novoflexvsdapter both don’t focus to infinity by far.

            The TAP is the only one which still focuses slightly beyond infinity in my case. Without the Plano lens it focuses far beyond infinity, the other two Adapters just slightly.

  42. Bastian, what lens hood did you use for the Voigt VM 35 1.7 together with the front end filter?

    And if a polfilter or similar was used, did you put it directly on the lens under the front end filter?

    1. I don’t use any lens hood with this lens as I think it is neither necessary nor helping.
      You can put any filter on top of the front filter, with the setup I described in great detail
      you end up with a regular 52mm filter thread.

      1. Thanks! It’s just if I already have the small 46 filters, I can also put them below, right?

        A side question; do you also remember if the TAP Adapter also enabled infinity focus or only the fotodiox?

        1. You can do that, but I think it is pretty stupid as it will make changing or just adding a filter really fiddly and you are most likely to drop at least one in the field.
          Won’t work with TAP.

          1. Today I made two infinity pictures with TAP/Planoconvex and TAP/plain 35/1.7.

            Both had the same good quality. So it must be variations of the TAP?

  43. As I am selling Irix 15mm f2.4 (that was my primary astro lens) to buy the CV 21, I am thinking of opto sigma pcx filter for my CV35 ultron, but I have a few considerations –

    1) is it posible to use screw in filters (I have a red enhanser a.k.a. a light pollution redux filter ) on the pcx filter?

    2) with my cheapo close focus adapter the CV 35 focuses on infinity a bit before the hard stop – can I assume that with the pcx filter I will be able to focus to infinity? If not, is it possible to remove the shims like in the flickr shown for the ZM 35?

    Thanks very much for your trouble, really appreciate it… ?

    Cheers, A.

    1. 1) With the setup I described in great detail you end up with a standard 52mm filter thread that you can use for anything you like.
      2) I would not count on it, none of the helicoid adapters I used were short enough, but no chance knowing without trying. There are no easily removable shims.

      1. thanks! so I am good on the filter side and a little less on the adapter side…

        I guess I’ll give it a try and see what happens…

        Thanks again, much appreciated…

  44. Thank you BastianK, Phillip and all for this wonderful resource. I now have the 1.5m pcx’s on my cxg 21 and 28 and are now more than useable on my standard A7.
    Now able to sell my remaining G2 body – before it just becomes a paperweight.

    On the subject of adapters, i have a metabones which, i finally worked out how to use without stressing the screw drive but imho the Kippon type, when you get a nice one, is far far easier to use and the focus is much smoother

  45. Are the problems caused by rangefinder lens ray angles on the A7 cameras diminished at all if the same lenses are used on an APS-C camera like the A6500? One might think that as the ray angles are less extreme at the edges and corners of the smaller sensor that the distortions could be markedly diminished. Anybody have any experience with this?

  46. Thanks everyone here for creating & contributing to this wonderful thread and your painstaking research-much appreciated.
    I plan to use the CG 21, 28 with the Nikon Z6 and reverse 1.5pcx combo(TA-GA3 + TZE-01) based on reported Z sensor thickness.
    Any advice here that you could offer perhaps? Also for the infinity issue is there a workaround perhaps for day to day shooting scenarios?

  47. Really interested to try this, has anyone experience with the voightlander 40mm 1.4 MC?
    It seems I need the 110-0555E from EKSMA but would be good to hear from someone with more knowledge.

    1. I think somewhere here in the comments is the information that a PCX is a bit of a waste on this lens, as it simply isn’t a great performer.

      1. Thanks for the reply Bastian.
        The site is a great resource for me and others who have said the same. Keep up the great work! Cheers.

  48. Hi Philip

    Thanks so much for providing this very useful information. I have just ordered the Voigtlander Ultron 35mm f1.7 for my A7RII and would like to try the 5pcx filter you mentioned. Having some difficulty choosing the correct filter on Eskma website. Would you kindly post a link to the one you tested and (if it’s not too much trouble) also the step up/down rings required to fit this lens. Thanks again John

    1. I rather recommend getting the Optosigma filter. It is easier to get and cheaper.
      You can order it here, they will get you in contact with your local distributor.
      The article says exactly what kind of step up rings (any works, there are countless suppliers) you need and there is even an instruction with pictures.
      I am sure this will have you covered.

  49. Hi! Thanks for this unvaluable information!!!

    I am planning to buy the opto lens while in vacation, so i would like to know if i need the tools and rubber band for mounting the lens onto my contax G biogon 28mm or is it just clamping it between the adapters,

    Thanks so much for your help!

  50. Hi Bastien, I’m curious about Olympus OM 21 & 24mm f2 lenses. I’ve owned the 28mm f2 and used it on a7 and a7ii cams with good result and sold it because I didn’t enjoy the focal length. The character and handling were perfect but I wonder how they’d compare against the loxia 21 or voigtlander fe 21 f3.5. Any insight is appreciated, and thanks for all the work you do

    1. Those old fast wide angle lenses are absolutely no match for the newer ones.
      Back in the day there were no aspehrical elements so coma correction and corner sharpness is significantly worse.
      Furthermore those lenses weren’t produced in high quantities and so they are often sought after by collectors.
      The price does often not nearly match their actual value for photography.
      Therefore I do not recommend any of the old fast wide angle lenses, no matter whether we are talking about
      the Olympus 21 and 24mm f/2 or Nikon 24mm 2.0 and 35mm 1.4.
      Some of the Canon FD L lenses like the 24mm 1.4 are already using aspherical elements, but for the same price
      you get a new lens with the same parameters and better image quality from e.g. Sigma.

  51. Hello
    I read all this with passion and thank you for this enormous and useful work.
    However, I’m sorry I do not understand the installation of the PCX5 on the Voigtlander Ultron 35 1.7 … I know I’m not good! My wife tells me and she is right.
    I read and re-read, study the “step by step”, read the comments … but nothing works, I can not get the whole thing together.
    A short video with all the elements elements would be, I think, a real plus.
    Once again I am sorry for my lack of practical sense, but if a charitable soul could help me, I would be eternally grateful to him.

  52. Hello,

    I got myself the Voigtländer 35mm 1.7. It is really fun to use.

    Regarding glasses, laser2000 doesn’t send to private persons in Germany without VAT id (you need to own a company), but optosigma france is sending them for about the same price. Their support was very friendly.

    So I built everything, but I couldn’t find the right adaptor (I think I tried five already), amongst several K&F and Fotodiox.

    I also looked into shims: it seems that unscrewing the back lens a little fixes the focus-to-infinity problem (also there are shims underneath, however, I think this is not recommended because it would probably modify other lens-characteristics as well).
    I noticed that before reading the tutorials on the oder websites where they were explaining which shims to remove and which ones not to touch… Shims to remove are the ones under the bajonett, but are there any in the voigtländer?

    What other options do I have regarding the focus problem?

    1. The 35mm CV mounting plate doesn’t seem to be designed with shims. The plate edge is tapered and slightly overlaps the rear body of the lens, so it can’t be shortened. It’s possible that further disassembly of the rear lens assembly will expose some shims, but detailed info on how to disassemble the 35mm VM seems to be sparse so I personally wouldn’t attempt it without guidance… I would agree with others that the easiest way forward is trial and error with different adapters and getting lucky with poor tolerances.

  53. Hi Bastian,

    Similar to Martin as per above, I still struggle finding an adaptor that focuses to infinity for my Ultron vm35 with 5m pcx. Do you have a list of best options that by experience works for others?

  54. I know this is an older thread but hopefully someone is still using this PCX setup. I just ordered everything I need to assemble this to use on my Voigtlander 35mm Ultron F1.7. I am getting the 5m bare glass from Opto Sigma. When assembling this, which way would I put the glass in? Curved side up or down? When mounted on the lens will the curve of the glass be the same as the curve you see in lenses or will it be the opposite? I can’t seem to find the answer but I’m assuming it is curved side facing out since that’s how my contact lenses work in my eyes. Lol. Also. I can’t seem to find the particular rubber bands that the person who posted pics in Flickr of the assembly was using. Will any flat small rubber band work as long as it’s 1mm thick? I’m very excited to see how much this improves my 35mm on my A7R ii. Thanks an advance for any help.

  55. I saw a reference in this article to ‘shorter’ Leica M to NEX adapters….are there any specific known adapters that work?!

    I’m looking at modifying my Zeiss 25mm f2.8 ZM. Gorgeous, small and high resolution. However my concern is the reference of removing shims – I use this also on my Leica M so don’t want to physically modify this lens. .

    1. Lately the most successful way seems to be to order like 10 random cheap M-mount adapters, see which one works and sending the others back.

      I had luck with Fotodiox, others had look with K&F but in both cases there are also plenty of people that weren’t lucky.

  56. I was able to put the plano convex lens solution together quite easily — purchased the lens from Opto Sigma (https://www.optosigma.com/us_en/plano-convex-lens-50mm-diameter-1500mm-focal-length-400-700nm-SLB-50-1500PM.html), and they were very helpful and friendly. I find, however, that the stop-down adapter (from 55mm to 52mm) ends up adding quite a bit of vignetting, and unfortunately it does not look like the same 1500mm focal length (recommended for this set up) is available as a stock item in a larger diameter (e.g., Opto’s 60mm diameter lenses do not have that focal length). They do offer custom builds though so maybe that’s a possibility.

  57. Has anyone ever determined the proper PCX lens to use for the Zeiss 21mm ZM f/4.5 lens? I bought one to use on my A1; I used to work with a Hasselblad SWC years ago, and this lens feel very similar and is a joy to use for square format where it is flawless. But I’d also like to use it full frame. I’m not concerned about the color shift (I use Capture one; LCC files handle it competently), but I would like to deal with the curved field at the edges with a PCX filter.

    1. Not aware that anyone ever did, the 1500mm that worked well for the Biogon 21mm 2.8 might be a good start.
      These filters are strong though so you would need a noticeably shorter adapter to still be able to focus at infinity.
      Maybe it would be worth it to check out the Voigtländer 21mm 3.5 which is similarly small but doesn’t come with all those issues?

      1. Thanks. Unfortunately, I’m specifically after using a Biogon. As noted, I’m looking for that Hasselblad SWC look. So my best approach would be to first determine if I can settle on a solution to give me focus at infinity. I’ll review the options to see what I think would work for me. I have the lens in hand now, so I can begin to experiment. I really do not mind the issues (I do a lot of medium format photography with a bellows setup, so I’m a patient guy). Its the results I want.

      2. One last comment on this subject; I did find a very simple method to get good focus with the 21mm f/4.5 Biogon: the classic stop down, and shift the focal plane. It is helpful at f/5.6; it is quite good but not perfect at f/8; and at f/11 the depth of field is finally large enough to solve the smearing problem in the corners. The trick is to aggressively move the focus plan. You just want to catch infinity, which at f/11 means setting focus to 5 feet! Crazy, but really highly effective approach with an f/4.5 lens. I am still going to try a plano-convex lens, but at least I can cover 80% or more of my imagines in this manner without too much effort or concern when I can use f/11.

      3. I was wrong; one more post on this. OptoSigma charges way too much for shipping; I was able to get a 2″ (50.8mm) plano-convex for about $61, plus $13 for shipping, so I thought I’d try it. Works really well, crisp nearly to the corners at f/4.5, and by f/5.6 very very good. Can recommend it.
        I had to remove shims to reach focus; I couldn’t find a clear video on that step, though I did find one kind of dark that was enough to get me to experiment. I will post a full description of what I did and what the results look like on my blog, hopefully within a few days: https://ronwodaski.substack.com

          1. I have posted a two-parter to my blog covering software and hardware issues for using the 21mm Zeiss Biogon ZM. The first covers lens cast and vignetting. The second has lots of photos showing how to remove the shims. The shim removal should serve as a guide for some of the other lenses as well. I am happy to have found that shim removal is fairly easy, though of course there are risks in any such move. 😉



  58. Thank you for the update.
    Do you know of any test of the Voigtländer VM 2,0/50mm Apo-Lanthar on a Sony full-frame? I’m aware there is the E-mount version of this lens, but it has no AF, while one could adapt the VM version onto a Sony via an AF-adapter like TechArt…

  59. Hello Bastian,

    because of your great reports I bought the Voigtländer VM 1,7/35 + the 5m – PCX filter.

    But the problem of not being able to get to infinity proved difficult to solve.
    Even the hard to get (Germany) Hawks V5 could not deliver the shortened distance.

    But I found a solution, the Voigtländer VM-E V1.

    When the screws on the VM-E (M bayonet) are loosened, a washer (0.25mm) can be removed, and the VM 1.7/35 also comes back with the 5m PCX – filter, on infinity focus!

    I hope to have helped some people with this, it is certainly also interesting for other lenses.


  60. Hi Bastian,

    the cheapest way to modify the Contax G 2.8/28mm ist using a reversed Zeiss Proxar Lens in front of the Contax lens. I used a Proxar lens with 0,5 dpt (f = 2m), which I took out of the B60 filter thread.

    This works really good and the egdes get very sharp and contrasty, even fully opened. And the Proxar lens is coated very effective.

    Best regards,

    1. Would you mind sharing a picture and maybe a description how to put that filter on the lens?
      I bought an old Zeiss Proxar 2m 67mm (still have it) but it is from before the B60 era and has some CA issues…

      1. Hi Bastian,

        I don`t own the 28mm any more, but here I wrote something about it and I think you can see, that it performs not bad.


        Please scroll to article #20 and #29 (written in German)

        To adapt the bare proxar lens I used a step-up ring from 46mm, to 55mm and an empty 55mm filter without glass, because the proxar lens fits perfect in between.

        Best regards, Christian

  61. Excellent addition on how to access the shims on the 35mm 1.7 CV. I never would have guessed the mount was attached to the main barrel like that. Of course, removing them also involves picking up that fancy spanner wrench, but all things considered that wrench isn’t too expensive compared with some of the other professional options out there.

    If I still shot on Sony E I would be removing those shims asap, but I now shoot on Nikon Z, and on that system the lens works very well without any front correction filter or mods.

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