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 07/01/17: Voigtlander Nokton 50mm 1.5 and Leica Summilux 35mm 1.4 Asph non FLE added


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

I had already covered this topic in detail in my Ultron 28mm 2.0 review, so I reused parts of it here.

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. strong vignetting
  3. “corner smearing”

Color cast and vignetting are mainly influenced by the sensor design. The A7r is the worst, A7s(II) and A7rII fair 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

Still, there are options to correct this like corner fix or by the use of gradients in Lightroom, which I did for this shot:

Before: Ultron 28mm 2.0 @ 2.0 (green color cast uncorrected) | After: Ultron 28mm 2.0 @ 2.0 (color cast corrected in LR with gradients)

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

Update 03/03/17:
I have now gathered some experience with two 5m front filters and the Zeiss ZM 35mm 1.4, Voigtlander 35mm 1.7 and the Leica 35mm 1.4 FLE Asph.
In the above mentioned scenarios one of these front end filters will certainly help, but maybe not in the way you are hoping for, especially when focusing is on closer subjects near the borders of the frame.

Before: Zeiss ZM 35mm 1.4 @ 1.4 (no filter) | After: Zeiss ZM 35mm 1.4 @ 1.4 (5m plano-convex front filter)

Before having used these filters I often got shots like the one shown as “Before” and I was always hoping that by the help of one of these filters the edges will be as blurred as the center.
I now got the chance to check this myself and found the edges with filter (“After”) only show marginally more blur but the center is significantly less blurred.
What is the reason for this? As you will see in the next chapter the focal plane is bend when using rangefinder wide angle lenses on the Sony A7 series cameras. So when you focus on something near the border of the frame (the lamp post in the example above) you need to focus your lenses closer than normally, and as you know: if you set your lens to closer distances the background will be more out of focus.
With a flat plane of focus (which is pretty much achieved when using the correct front end filter) you don’t have to use a closer focus setting for subjects near the border of the frame, therefore the background in the center will be less out of focus.
Furthermore fast rangefinder lenses show severe optical vignetting compared to some modern DSLR lenses and optical vignetting also has an influence on sharpness near the borders (increased) as well as blur (decreased).

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 differently
  • 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.

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:

Before: Contax G 21mm 2.8 @ 2.8 (no filter) | After: Contax G 21mm 2.8 @ 2.8 (1.5m plano-convex front filter) ©HaruhikoT

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

Before: Contax G 21mm 2.8 @ 2.8 (no filter) 100% crop | After: Contax G 21mm 2.8 @ 2.8 (1.5m plano-convex front filter) 100% crop ©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“.

Zeiss ZM 18mm 4.0 Distagon

Front end filter: Zeiss Proxar 0.5m Not tested!

For infinity focus a shorter adapter and/or the removal of shims is necessary.

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.

Zeiss ZM 25mm 2.8 Biogon

Front end filter: Zeiss Proxar 1m (B57 Ø50mm) Tested

For infinity focus a shorter adapter and/or the removal of shims is necessary.
For further information 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.

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 (or the removal of shims if possible with this lens) is necessary. For me this adapter worked.
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

For infinity focus a significantly shorter adapter and 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.

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!
I have already ordered a 5m PCX filter for my Zeiss ZM 35mm 1.4 and can’t wait for it to finally arrive 🙂

Further Reading


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My name is Bastian and for many years I have been mostly shooting Nikon DSLRs. As of today I have made my transition from Nikon to Sony and I am mainly using small but capable manual lenses. My passion is landscape photography but I also like to delve into other subjects from time to time.

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81 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. 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!

  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. 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… 🙁

  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. 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….

  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.

  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.

  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? 🙂

  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 ?

  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 🙂

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