Fotodiox x Novoflex x Voigtlander: M-mount adapter cagematch

Started Nov 19, 2013 | Discussions thread
Tom Caldwell
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Re: Fotodiox x Novoflex x Voigtlander: M-mount adapter cagematch
In reply to turnstyle, Nov 20, 2013

turnstyle wrote:

Tom Caldwell wrote:

If the adapter focuses slightly before infinity then this is designed in and not a manufacturing fault. The manufacturer does this as a deliberate act as they cannot pre-determine every faulty focus lens that might be used on them.

I think this is not so clear. There is certainly a specific distance that it should be machined to. Some manufacturers say you should hit infinity focus at the infinity stop -- others say you may focus past infinity.

If you ask Voightllander, they will tell you theirs should stop at infinity focus -- and if you tell them it doesn't, they'll tell you to bring it back to where you purchased.

Also, I don't see why an adapter manufacturer should intentionally build a shot adapter just because a lens mounted on it might be long.

I found this post informative:
http://www.dpreview.com/forums/thread/2949181#forum-post-37648490

Specifically, the issue regarding 9.80 mm vs. 9.72 mm -- but perhaps his measuring tool was off?

I hardly see myself as an expert but more someone who listens and observes.

There is a tale that when the Russian inherited German technology either by blatent copying pre WWII or via war reparations they ended up with two quite useful if more crudely made Leica-type bodies and only one Leitz-type lens, the rest were Zeiss derivatives.  For some reason the theorectica fit of the Zeiss lenses caused problems and  for a while at least the camera/lens combinations had to be set by individual adjustment per camera.  Some might pounce on this as an example of shoddy Russian workmanship but I did see a serious article on this subject explaining some difference in the lens registration as the true problem which seemed believeable.  There is also the story that when Canon first copied the Leica design (as many others did) they had assumed that the thread was metric and not imperial and as a result for a while the mount was not LTM compatible.

From where I stand it is a convenience issue.  If anyone has a suite of perfectly adjusted lenses set to infinity focus then by all means buy an adapter guaranteed to also be perfectly adjusted to infinity focus.  Obviously only the best will do.  But my "Heinz 57 varieties" bunch of lenses does not come with such a guarantee.  However I hardly notice the lens infinity focus problems because my adapters have taken up the slack.  Maybe all my lenses have proper infinity focus?  I simply do not know.  But what I do know, and this distresses me, is that I get the occassional lens that will not focus to infinity.  I blame the lens and not the adapter as the same adapter will focus many other lenses at true infinity of slightly past infinity.  Perhaps too many oddball lenses but I simply have to accept going past infinity from time to time as a nuisance that I can overcome by the bigger nuisance of adjusting the lens rather than the adapter - but this is a time consuming exercise and I usually put up with the smaller nuisance factor.

Whilst talking about it I find that the majority of my lenses actually do focus correctly at infinity with cheap adapters which begs my conclusion that paerhaps some of the focus past infinity problems are as much lens-related  as adapter-related.

Pay some extra for the guaranteed elimination of adapter nuisance and send the adapter back if your lens infinity focus is incorrect.

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Tom Caldwell

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