Fotodiox x Novoflex x Voigtlander: M-mount adapter cagematch

Started Nov 19, 2013 | Discussions thread
Tom Caldwell Forum Pro • Posts: 33,050
Re: Fotodiox x Novoflex x Voigtlander: M-mount adapter cagematch

Letsgokoulos wrote:

turnstyle wrote:

Sorry, I'm losing track -- the Fotodiox properly hits infinity?

Even the high quality adaptors will not guarantee accurate infinity on the lens hard stop. They need to have a tolerance, for mechanical reasons and because each lens may have slightly different settings. Any good quality adapter will make sure that you can go past infinity, so if you want infinity you have to manually adjust before the infinity mark.

You may be lucky and have the adaptor providing infinity with a lens, but it most likely will not work 100% with other lenses in the same mount.

If you want an accurate hard stop on infinity, the only solution is shimming the adaptor. I have made the choice of cheaper adaptors so I could purchase one per lens and then shim it accurately. Since it is dedicated to a specific lens, it never is dissassembled and therefore does not deteriorate.


I agree Marc and note that all the very expensive Canon EF telephoto lenses (at least) are deliberately made to focus past infnity to take into account the effect of heat. Canon make no bones about this and note it readily. I imagine that smaller lense less affected by heat may also have some smaller tolerance built in. Besides lenses potentially have a lot more mechanical tolerence discrepancy in construction than those of adapters. Older lenses at least needed a final focus adjustment at final assembly.

And so the debate over perfect infinity focus has many caveats. Obviously your solution to shim adapter/lens combinations to perfection is a good one. But might even then vary very slightly in extremes of weather. On smaller lenses it would probably take a focus genius to perceive.

However making an issue out of focus before infinity is one of the lesser problems presuming that the "operator" (photographer) has checked focus as part of a normal shooting routine. It might be a nuisance - but photography is a discipline as much as any other craft and not "painting by numbers". With AF lenses of course the user would certainly never know.

However while I admit to a small focus beyond infinity as an "acceptable problem" a substantial focus beyond infinity is not.

The other thing that never gets discussed is the effect of hyper-focal distance when shooting infinity. This has never before crossed my mind. If a lens can focus past infinity and at the infinity stop is out of focus - does part of the dof always be oof as long as the hyper-focal area exists? Or is there some sort of auto-adjust to only focus on the focused part of the hyper-focal? This might be the real problem (if true) of a lens/adapter focusing beyond infinity. But then of course all Canon EF telephotos would have an instant problem unless the temperature was "just right" (quite hot I would think).

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Tom Caldwell

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