Shimming lenses | The case of the Minolta MD 45 2,0

[lumens pixel]

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

[BrianSVP]

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?

[lumens pixel]

[RokkorDoctor]

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.

[lumens pixel]

[RokkorDoctor]

[lumens pixel]

[Max78]

[Alsatian2017]

[lumens pixel]

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