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Shimming lenses | The case of the Minolta MD 45 2,0
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PostPosted: Sun Sep 08, 2024 10:41 pm    Post subject: Shimming lenses | The case of the Minolta MD 45 2,0 Reply with quote
Some of you have shimmed your adapters since you are well aware of the disastrous consequences when using zooms or floating elements designs.

But what about the lenses themselves.

I am very fond of the Minolta MD 45 2,0 and have posted a number of pics taken with this lens.

I indicated that for landscape use f6,7 was required for uniform clarity.

I took the lens for a walk a few days ago and took a pic of a distant subject at f3,5. I was underwhelmed by the result and after further testing realised that the lens did not quite reach infinity which was masked when further stopping down.

I had two other Minolta lenses that would not quite achieve infinity on the shimmed adapter but all the others were fine. One would have open the lens to adjust register but I am lazy and the adjustment to be done was quite minimal.

So rather than tinkering the lens with uncertain results I took off the four layers of tape from the adapter's mount and replaced with one. I could focus a hair past infinity but then realised when focusing at distant objects at f2,8 that left and right side of the image required different focus settings. All that was masked by landscape use at f6,7.

Since I passed infinity more on the right than on the left side I added a layer of tape on the left side of the lens mount, preserving the symmetry of the adapter for the other lenses. When focusing for the center this improved borders and corners on all the image thanks to a better aligned focus plane.

I also had to make the same adjustment on my MDIII 50 2,0 and MDIII 28 2,8 with significant improvements with just one layer of tape on the lens mount.

These lenses now shine even more than before and I was quite happy that I have spent the whole day tinkering and testing the lenses.

Of course, before engaging in this process I did check the symmetry of the adapter with a micrometer and that the mount was properly screwed on the camera.

Here is a result that would have been difficult to achieve with the MD 45 at f4,5

Eglise de Saint-Cloud by lumens pixel, sur Flickr


PostPosted: Mon Sep 09, 2024 12:38 am    Post subject: Reply with quote
This is among the easiest lenses to adjust on infinity there is. As in it would take significantly less time than shimming your adapter. As in 2-3 minutes, tops.

And if you are having trouble with 5 different lenses on the same adapter, it sounds like it's a crap adapter. If you really value your time, why not just replace it rather than monkeying around trying to balance shims?


PostPosted: Mon Sep 09, 2024 7:25 am    Post subject: Reply with quote
BrianSVP wrote:
This is among the easiest lenses to adjust on infinity there is. As in it would take significantly less time than shimming your adapter. As in 2-3 minutes, tops.

And if you are having trouble with 5 different lenses on the same adapter, it sounds like it's a crap adapter. If you really value your time, why not just replace it rather than monkeying around trying to balance shims?


The adapter, as shimmed, is spot on for 19 other lenses. So I guess the problem was not on adapter’s side.

Having said that I have never adjusted infinity on a lens and if you have a link pointing to the procedure for that lens I would be grateful.


PostPosted: Mon Sep 09, 2024 9:28 am    Post subject: Reply with quote
I agree with BrianSVP that in the long run you are better off adjusting your lenses rather than constantly re-shim your adapter.

As you found out, parallelism of the mount is paramount (no pun intended) when shooting at wider apertures.

For those not comfortable doing that, there should be a market for adapters that offer a very small-travel infinity-calibration helicoid, with a fine thread and no play. Can't be that hard to manufacture. This wouldn't work for zooms and lenses with floating focus, but for unit-focusing lenses it would be a practical solution.

I believe a few of such adapters exist for e.g. M42, but from what I have seen they are bit clunky in their design & execution.


PostPosted: Mon Sep 09, 2024 1:12 pm    Post subject: Reply with quote
RokkorDoctor wrote:
I agree with BrianSVP that in the long run you are better off adjusting your lenses rather than constantly re-shim your adapter.

As you found out, parallelism of the mount is paramount (no pun intended) when shooting at wider apertures.

For those not comfortable doing that, there should be a market for adapters that offer a very small-travel infinity-calibration helicoid, with a fine thread and no play. Can't be that hard to manufacture. This wouldn't work for zooms and lenses with floating focus, but for unit-focusing lenses it would be a practical solution.

I believe a few of such adapters exist for e.g. M42, but from what I have seen they are bit clunky in their design & execution.


I think it will be difficult to build and market at decent prices. I noticed on some of my nFD lenses that there is some play on the helicoid of the lens that can have a significant impact on border and corner sharpness. So maybe the adapter with micro adjustment would work fine for a period of time but when the grease starts to dry or the metal to wear the problems will surface again.

On my (excellent) copy of the nFD 35 2,8 I press lightly on the helicoid towards the camera to suppress the play. But that is more of a problem for tripod use. You would not notice the problem without hood. The weight of the hood has an impact on a less than perfect helicoid...

But back to these Minolta, I think that shimming an adapter for 80% of the lenses is not so far from the truth. Shimming then the lens, or as you suggested exactly, the register seems good policy. But when you have to adjust a lens for parallelism it is certainly preferable to act on the lens itself rather than on the adapter if you do not intend to dedicate an adapter per lens, which I don't since I value weight savings for my practice.


PostPosted: Mon Sep 09, 2024 6:32 pm    Post subject: Reply with quote
lumens pixel wrote:

I think it will be difficult to build and market at decent prices. I noticed on some of my nFD lenses that there is some play on the helicoid of the lens that can have a significant impact on border and corner sharpness. So maybe the adapter with micro adjustment would work fine for a period of time but when the grease starts to dry or the metal to wear the problems will surface again.

On my (excellent) copy of the nFD 35 2,8 I press lightly on the helicoid towards the camera to suppress the play. But that is more of a problem for tripod use. You would not notice the problem without hood. The weight of the hood has an impact on a less than perfect helicoid...

But back to these Minolta, I think that shimming an adapter for 80% of the lenses is not so far from the truth. Shimming then the lens, or as you suggested exactly, the register seems good policy. But when you have to adjust a lens for parallelism it is certainly preferable to act on the lens itself rather than on the adapter if you do not intend to dedicate an adapter per lens, which I don't since I value weight savings for my practice.

if that nFD lens is helicoid focus than the play likely means its needs new helicoid grease. The grease not only prevents wear and provides the right level of damping, but it also stabilises the helicoid.

FWIW, the main reason I like to calibrate my lenses' infinity focus is because I just like to know that the focus scale is correct (or at least as correct as can be), and that I can rely on the hyperfocal distance scale with some degree of confidence at least (I use those a lot on wide-angle lenses).

In practice I rarely have a need to focus a lens at infinity, or even near it.


PostPosted: Mon Sep 09, 2024 7:03 pm    Post subject: Reply with quote
RokkorDoctor wrote:
lumens pixel wrote:

I think it will be difficult to build and market at decent prices. I noticed on some of my nFD lenses that there is some play on the helicoid of the lens that can have a significant impact on border and corner sharpness. So maybe the adapter with micro adjustment would work fine for a period of time but when the grease starts to dry or the metal to wear the problems will surface again.

On my (excellent) copy of the nFD 35 2,8 I press lightly on the helicoid towards the camera to suppress the play. But that is more of a problem for tripod use. You would not notice the problem without hood. The weight of the hood has an impact on a less than perfect helicoid...

But back to these Minolta, I think that shimming an adapter for 80% of the lenses is not so far from the truth. Shimming then the lens, or as you suggested exactly, the register seems good policy. But when you have to adjust a lens for parallelism it is certainly preferable to act on the lens itself rather than on the adapter if you do not intend to dedicate an adapter per lens, which I don't since I value weight savings for my practice.

if that nFD lens is helicoid focus than the play likely means its needs new helicoid grease. The grease not only prevents wear and provides the right level of damping, but it also stabilises the helicoid.

FWIW, the main reason I like to calibrate my lenses' infinity focus is because I just like to know that the focus scale is correct (or at least as correct as can be), and that I can rely on the hyperfocal distance scale with some degree of confidence at least (I use those a lot on wide-angle lenses).

In practice I rarely have a need to focus a lens at infinity, or even near it.


I definitely need to develop my skills to better service my lenses.


PostPosted: Mon Sep 09, 2024 8:03 pm    Post subject: Reply with quote
RokkorDoctor wrote:
lumens pixel wrote:

I think it will be difficult to build and market at decent prices. I noticed on some of my nFD lenses that there is some play on the helicoid of the lens that can have a significant impact on border and corner sharpness. So maybe the adapter with micro adjustment would work fine for a period of time but when the grease starts to dry or the metal to wear the problems will surface again.

On my (excellent) copy of the nFD 35 2,8 I press lightly on the helicoid towards the camera to suppress the play. But that is more of a problem for tripod use. You would not notice the problem without hood. The weight of the hood has an impact on a less than perfect helicoid...

But back to these Minolta, I think that shimming an adapter for 80% of the lenses is not so far from the truth. Shimming then the lens, or as you suggested exactly, the register seems good policy. But when you have to adjust a lens for parallelism it is certainly preferable to act on the lens itself rather than on the adapter if you do not intend to dedicate an adapter per lens, which I don't since I value weight savings for my practice.

if that nFD lens is helicoid focus than the play likely means its needs new helicoid grease. The grease not only prevents wear and provides the right level of damping, but it also stabilises the helicoid.

FWIW, the main reason I like to calibrate my lenses' infinity focus is because I just like to know that the focus scale is correct (or at least as correct as can be), and that I can rely on the hyperfocal distance scale with some degree of confidence at least (I use those a lot on wide-angle lenses).

In practice I rarely have a need to focus a lens at infinity, or even near it.


IMHO, it is the well known problem of the aging of the bearings in Canon nFD lenses. One very characteristic example is Canon nFD 200/4 macro.

There is a topic on this subject on German forum: https://www.digicamclub.de/showthread.php?t=16843


PostPosted: Mon Sep 09, 2024 8:44 pm    Post subject: Reply with quote
Max78 wrote:


IMHO, it is the well known problem of the aging of the bearings in Canon nFD lenses. One very characteristic example is Canon nFD 200/4 macro.

There is a topic on this subject on German forum: https://www.digicamclub.de/showthread.php?t=16843


Not quite since the Canon nFD 35 mm f/2.8 has no silder bearings (as in zoom or floating elements lenses), the focusing being solely helicoid-driven.


PostPosted: Sat Sep 14, 2024 10:07 pm    Post subject: Reply with quote
This focal length feels very natural to me. If I like the scene, I just take the picture and I see it as I remember it.



Manches à air | Windsocks by lumens pixel, sur Flickr
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