Possible Effects of Using Adapted Lenses

[Glenn NK]

Two interesting articles from Lens Rentals.

The first one dealing with adapters started the ball rolling:

http://www.lensrentals.com/blog/2014...adapted-lenses

This second article may be more useful to more photographers:

http://www.lensrentals.com/blog/2014...does-it-matter

Glenn

[Joan]

Quite interesting articles, indeed.

(To really grasp them I have had first to understand what MTF charts are what are meant for:
http://photographylife.com/how-to-read-mtf-charts)

Should we have to conclude from the articles that really meaningful MTF charts should be made pairing a given lens with a given body ?

[Glenn NK]

Should we have to conclude from the articles that really meaningful MTF charts should be made pairing a given lens with a given body ?

That's what I take from the article; quoting directly:

3) When testing a lens using Imatest, DxO, or other computerized target analysis on a camera the lens is NOT designed for (testing a Leica M mount lens on a Sony A7r body, for example) the test shows accurately how the lens performs on that body but we can’t make any general conclusions about the lens. It might be better on it’s native body.

I’ll expand on number 3 just a bit. If a tester tests a Leica lens and a Canon-mount lens by mounting both to an A7r, he has created a valid test showing how those lenses perform on that camera. That is good, practical data for any A7r owner to have. But it’s completely false to use those test results and say the Leica lens is better than the Canon-mount lens. The results might be totally different on another camera, or if each was shot on the camera it was made for.

It's becoming more common for lenses of other brands to be used - sometimes referred to as "mix and match" approach. As it stated further on, there are some lenses (rangefinder for example) that give poor results on non DSLR bodies.

I often read comments on forums that make disparaging remarks about lab tests, saying for example, "I shoot in the real world", thereby implying that accurate tests under controlled conditions somehow invalidate the concept of lab testing and that only going out and taking images is the more valid approach. Nonsense.

Glenn

[inkista]

Wonder if this explains the issues folks have been having with wide-angle M-mount lenses on the A7.

[Manfred M]

The next question is of course, do lenses of the same manufacturer perform equally well on the different camera body lines?

When we look at the chart, there appears to be some variability in stack thickness across various camera body models within the cameras produced by the same company.

[Glenn NK]

Kathy: I personally think so.

Manfred: That's a good question. I use a 30D and 5DII, both with the same lens set (where permissible), and if the 5DII sensor stack is the same as the 5D, I could possibly notice a difference if I looked (which I haven't). Which then relegates me to the oft noted category of "ignorance is bliss".

I think this could be a bit of a wake up call for those that freely mix and match lenses, bodies, and converters.

I'll be following Roger Cicala's website carefully.

Finally, I'd be quite surprised if designers like Canon and Nikon were not aware of this optical phenomenon, and be even more surprised if they haven't taken it into account during lens design.

Glenn

EDIT: Just read all the reader's comments on LensRentals: it seems to be mostly a problem with M43 bodies using other lenses, particularly film lenses or Leica M lenses.

[inkista]

I'm not so sure it's about "taking into account" the stack when lens designing as much as it's simply testing all the designs on bodies that actually have the stack, rather than on test equipment that doesn't.