Tuning adapters for infinity focus and reflections – How To

Since a few people asked this is a short how-to on how I tune my adapters. As you will notice I am far from a perfectionist but so far my method has worked well for me and I think it could solve issues for some of you as well.

Correcting Infinity Focus

The Issue

Most adapters, not only the cheap ones, are a bit too short. This means that the markings on your lens are off and you can focus your lens behind infinity so the infinity hard stop of your lens won’t work. It makes sense for adapter manufacturers to make their adapters a bit too short because your Sony’s flange focal distance varies a bit and so does lens calibration. If their adapters were exactly as thick as specified there would be quite a few cases were people couldn’t focus at infinity which is way more annoying than a focus scale which is a little off.

But a too short adapter can also have negative impact on the image quality if you use a lens with floating elements. Especially with fast wide angle lenses you can get serious field curvature issues as many users of the Metabones Canon EF adapters have found out.

Important notice: This fix only works if you can focus at infinity and beyond! If you can’t reach infinity the fix will only make matters worse.

The lens is focused as infinity but the focus scale is way off because the adapter is too short

The Idea

To fix the issue you want to make your adapter thicker. Thankfully this is easily done because on about any adapter I have come across so far you can unscrew the mount and add some spacing material.

Materials

You could use just folded tinfoil from your kitchen which is basically free. I use self adhesive copper foil (affiliate link) which is affordable and easy to handle. You could also make yourself some metal shims like they are used in many lenses but in my eyes that is overkill.

Tools 

  • Finer scissors
  • A fine decent quality screw driver

The Fix

  1. Step: Unscrew the mount of your adapter

2. Step: Add shimming material

This is the only part which is a little tricky. You need to add the right amount of shimming material. So better start with a little less than needed, test and then add some more until infinity focus is spot on.

Step 3: Put the screw back in and test

After you have put the screws back in you need to test if you added the right amount of shimming material. So open your aperture as wide as possible and focus at an object far away. If the focus scale shows infinity you are done. If not go back to step 2 and add some more material.

Limitations of my method

My method won’t result in a super exact alignment of the adapter. It is precise enough for any lens I have tested so far but those were older wide angles which have softer corners at wider apertures anyway which might mask issues. A modern super wide angle like the Laowa 2.8/12 or Nikon 1.8/20 will be more sensitive. My method might be precise enough for them or not, I simply haven’t tested so far.

Adapter Reflections

The Issue

Especially cheaper adapters are often quite reflective which can cause reflections which degrade image quality.

left: After my fix is applied right: Unfixed adapter with strong reflections

Adapter reflections do only happen if you have a very high contrast in your image and some lenses are more susceptible to it than others. See the image below for a demonstration of how adapter reflections can destroy your image.


before: adapter reflections cause annoying flares after: the same scenario with fixed adapter

Adapter reflections do not happen often and you can shoot an reflective adapter for a log time without running into issues but since the fix is easily applied I can only recommend to do it.

The Fix

The idea is simple: You want to cover the shiny inside of your adapter with something which absorbs the stray light. I have seen solutions ranging from light absorbing paint over custom made light baffles to felt like material. I use DC-fix black velours (affiliate link) which absorbs light very well and it is easily applied because it has a self-adhesive backside.

Step 1: Get the right measurements

You could take very exact measurements of you adapter and then calculate the exact measurements you need for the felt-like material. I simply took a piece of paper, took a rough measurement on the correct height, inserted into the adapter and then cut it to length.

Step 2: Cut material to size

I then used this mask to cut my DC-fix black velours to the right dimensions.

Step 3: Apply material

Now I just had to put the material into the adapter and I was done.

Photographing light absorbing material is quite hard but I think it is obvious that the adapter now reflects much less light.

Step 4: Vacuum the adapter

Do yourself a favor and use a vacuum cleaner to remove any fuzz from the velours. I haven’t had any issues with threads on my sensor after vacuuming.

If you have come up with a better method please let us know, so that we can all benefit.

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I like to be outside with my camera and I am also a gear head with a love for manual lenses.

42 thoughts on “Tuning adapters for infinity focus and reflections – How To”

  1. I had one adapter for a Minolta /Nex where the lens wouldn’t lock on the adapter. This can be caused by two issues.
    1: There is a little screw on the back of the mounting plate that is used as a stop. Remove this totally ( put in a white dish 🙂 ) and check does the lens now rotate enough to lock. If it does you have 2 options, put back the screw and file flat the side of the screw that hits the mount allowing it lens to rotate further or file the side of the locking plate that drops into the notch. You can see the plate in the pic in step 3 above. To check how much more you need to rotate to fit the adapter to the lens and look down into with from the camera side. Note: If you leave don’t put back the screw your lens can keep rotating around
    2: The locking plate is too wide for the notch in which case file down to the required width.

    I had one other that I couldn’t fix simply because the piece sticking out of the locking plate was too short to lock into the notch on the lens.

    I am really surprised that manufacture haven’t designed a mount where one part screws into another along with a locking ring to lock infinity position. Apply a bit of loctite or the like to the locking ring then and it would never move again

    Thanks for the info on the flocking, I wasn’t sure what to look for when I considered doing it before

  2. Just one thing looking at the placement of the shim material, Its nit picking but I would recommend getting a piece at the locking side of each screw hole as well so as not to create an issue of the plate bending downwards on that side. Assuming that everything is parallel anyway. From pic 3

    Also if anyone knows the exact specification of the screws so slightly longer ones can be got it would be great info to have. Some are very short if you have to shima lot.

    I also saw a post where one guy after shimming, taped neatly around the adapter where the plate goes on to the adapter to eliminate any possible light leaks in that area. He had shimmed a good bit for one lens but no harm in doing it while you are at the work yourself

  3. If you want to be *really* obsessive you could do what I’ve done a couple of times and make a rectangular mask out of two pieces of flocking (I use self adhesive telescope flocking which may be very similar to your velour) stuck together to ensure that it’s matte on both sides, with the sticky parts left separated at the base to act as tabs. I make one for both ends of the adapter. It’s important to make the rectangular hole just a bit larger than in a purpose built masked adapter, because you’ll never get the alignment exactly right, and you need some room for error. I have seen situations in which this makes a (small) difference…

  4. Can you recommend any adapters that aren’t reflective on the inside? (Particularly for Nikon manual focus lenses)

  5. Hi Phillip, I have a question for you about adapted wide angle lenses: given your vast experience do you see often uneven corner performance caused by the adapter itself? I’m asking because I think I clearly see the problem with all my wides: a 24 fdn Canon, a 20 fdn (with rayqual adapter), a 28 distagon c/y with cheap adapter, a minolta 24-105 @ 24 with ea3 and 4 sony adapter. Is it possibile? Thank you in advance.

    1. In theory adapters can cause such issues and when I tuned one of my adapters in a very crude way I saw a filted image plane. But I have never seen any issues with a normal adapter and with a Rayqual I would be very surprised if your issues were due to the adapter. Do you have access to other WAs which have symmetric corners? Because you camera mount could be the culprit.

  6. I hope the camera mount is ok, but I guess it’s difficult to check it… probably I have a bad combination of lenses+adapter. For example the 24 fdn although in excellent conditions has focusing ring play. I read this can cause problems to the optics. Maybe also the 24-105 af has some decentring. But how can you really understand if the focus plane is tilted or the lens is defective?

    1. If you vave issues with every single lens/adapter combination you own then there is a pretty high chance that your mount has issues. Maybe you can borrow other native lenses/adapters and check if those work better. If they don’g it is almost certaibly the mount.

  7. Hi Phillip,

    Great article!
    I have a MD 24 2.8 which has so far disappointed me because of extreme softness in the corners. But having read your article, I gave it another try with a different adapter – et voila: corner sharpness is much improved. I noticed that the first adapter focuses quite a lot before infinity. With other lenses this has never been a problem for me. Do you know why this is so apparent with wide angles like the 24mm?

  8. Don’t you think the adhesive layer of the copper foil might be squeezed over time, changing the adjustment?

    BTW, I second the Tamiya model paint XF-1, good alternative.

    1. I don’t think that it’s thickness is relevant relative to the thickness of the copper foil. But time will tell. So far I have used it for over a year and not noticed any issues.

  9. I would also recommend the Tamiya model paint XF-1 it’s cheap and the 10ml size will be more than enough to cover multiple adapters.

  10. Hi Philip, first off I have to say I live your website and you have inspired me to buy the Sony a7 and shoot manual lenses. Thanks you for your work!

    I used the Minolta 58mm 1.2 with a K&F Adapter which worked out really well except for really severe reflections caused by the adapter. I decided to use the flocking material and it worked out perfectly. However, while I applied the material to the adapter, a lot of particles got loose and tiny little velour pieces fell out. I can’t help but worry about my lens and camera. Having used this solution for a while, what’s your experience with this? Did you notice any velour fallout in the lens or on the sensor? Is there any way to avoid this?

    1. Did you use a vacuum cleaner on your adapter? I usually do that and haven’t noticed any issues. An alternative method would be to use light absorbing paint which other people have done successfully but I have no personal experience with that.

  11. Phillip, are you sure that infinity focus loss is due to adapters that are too short, rather than too long? I did your shim mod, that did not help. Twice, so the screws were barely in. Then i ground the faceplate down by a mm, that didnt work. The adapter is now loose on the camera, not a workable solution. The problem is getting focus at infinity with a Nikkor 600mm f5.6 IF ED. No problems on my A6000, but my A7rii will not focus. Same issue with a 300mm F5.6 nikkor. Fine on yhe A6000 but wont go to infinity on the A7rii.

    1. I am sure that a too long adapter will result in your lens not being able to reach infinity ;).

      If your adapter is too long I wouldn’t bother with it and spend 20 bucks on a replacement. You might be able to fix it but only with considerable effort and uncertain results.

      Sadly Sony’s E-mount cameras vary quite a bit in flange focal distance which is why every adapter I have used so far is too short.

  12. Unendlich Fokus korrigieren
    Die Adapter sind ungenau nur ab 120€ gibt es gut genaue Adapter wird ja oft behauptet.
    Bei Kamera und Objektiv ist das Auflagemaß das Nennmaß 18 -0,02 /-0,06.
    Nur bei der A6000 liegt der Bajonettring auf Kunststoff, dazwischen ist noch die Zwischenlage mit dem Bajonettklauen auch aus Kunststoff . Die 18mm habe ich nicht überprüft, aber den Sony LA-EA4 Adapter habe ich gemessen er hat -0,05mm und ist somit auch nicht besser als viele NoName Adapter. Fast alle Adapter liegen zwischen 0,05 bis 0,1mm zu klein, der K&F wirkt sehr gut ist aber beim Auflagemaß auch nicht besser. Bei dem K&F Adapter II sind beide Bajonette aus Messing und verschraubt, dadurch wird das Auflagemaß aber nicht genauer sonder eher schlechter. Dein Ansatz solang zu unterlegen bis die Skala auf Unendlich zeigt ist ja richtig, aber ich stelle einfach nur scharf, oft mit einem Helicoid-Adapter.
    Gruß Ewald

  13. I have found that the infinity stop on my lenses is not always in the right place. I have used this method and my Minolta F4 70-210 is now correct at infinity, but other lenses focus beyond infinity, Minolta MD 35-70, Minolta Rokkor 24 and Tokina RMC 17, the last is the worst. Does that mean each lens needs its own adaptor or do the lenses need calibrating?

    1. Lenses all vary in a bit in spec, and final infinity focus is a combination of the lens and adapter.

      Playing with a cheap adapter is less scary than calibrating a lens.
      Also, multiple calibrated adapters is cheaper than sending even one lens off for calibration if you don’t do it yourself.

      Most of us tend to give any lens we use regularly it’s dedicated adapter anyway, so there’s no messing around with both lens and adapter if you are changing lenses.

      The other thing to do is relax and don’t worry. So long as you can achieve infinity, just remember where the real infinity is a bit before it. Especially with larger lenses infinity may vary with temperature too; when it’s very cold you may find you have to focus behind the infinity point anyway.

  14. For $1 at of all places, The Dollar Store? Hair Ties with no clasp 15 of them all black (a lifetime supply), stretch them around the gaps where the lens mounts and adapters mount to get anal over light leaks … they work and there’s no magic

  15. DC-fix black velour didn’t work for me as it didn’t want to stick to my k&f concept adapter. Actually it didn’t want to stick anywhere I’ve tried it. Pretty disappointed with that – waste of money. Waiting for xf1 paint now. I really need that working as I get TERRIBLE flare with both of my 50mm Pentax (K and M ver) lenses.

      1. Tried again just while ago and was bit closer to succeed. Looks like it has to be put like a layer, rather than just stick like an adhesive tape. But I failed badly again:-) Will try again later but I need to calm a bit down as I get frustrated with things like that very easly.

        I managed to find some nice Pentax K lenses (28f3.5, 35f3.5 and 55f1.8) but especially with last one I get pretty bad flares, exactly like it’s shown above in your tutorial. Same with later version of that lens (A50mm1.7)… Having said that, I don’t mind to pay more for one proper adapter, as I’m attached to Pentax system, and need only one. Is there any particular brand you can recommend that don’t require any additional tweaks to reduce flare? It looks like 50-55mm focal lenght is very prone to do that. The other two I mentioned are fine… Rayqual are pretty hard to find at the moment, what about Novoflex? Have you ever tried Gobe adapters? They’re more of k&f price range…

        1. @Jacek

          My Pentax K 55/1.8 flares isn’t flare resistant too. I flocked my adapter, but it still flares like hell. Similar to other legacy gauss design lenses.

  16. I haven’t read all the comments, but you can calibrate the adapters for infinity and get a fairly decent centering (0.02/0.05mm precision) by measuring the adapter length with a (digital) caliper instead of checking the focus through the lens.

    Let’s say that you want to correct a PK adapter.

    https://en.wikipedia.org/wiki/Flange_focal_distance

    PK flange: 45.46 mm
    NEX flange: 18 mm
    Difference: 27.46 mm

    You just take measures of the length at 4, 6 or 8 points and add tinfoil until all the sides give you 27.46 mm (or very near depending on your patience).

    This may not work with some mounts like Canon FD (I haven’t tried), but most mounts are OK.

  17. For the reflections I just paint the inside with flat chalkboard paint.

    I also manufacture an inside donut with cardboard and paint it with the same paint (indian ink is also suitable here) so mount reflections (if any) are blocked.

  18. Does putting in small pieces in individual spots throw off the alignment or focus from side to side? Just wondering if it would be possible to get something circular instead… I’m having an issue with my k&f filter for an MD 50mm f2 on a Fuji body and infinity focus is very soft. Do you know how much material is generally required? Just wondering what exactly to buy in order to create the shim. I’m in Australia.

    1. It is not the most precise method for sure but precise enough fot my applications so far and a MD 2/50 should be uncritical.
      How much material is needed varies from adapter to adapter and camera and lens play a role as well.

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