Modify an M42 lens for infinity focus on a DSLR

philxthomas

philxthomas

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I have been experimenting and have discovered the adapter that lets you use M42 threaded lenses on a DSLR.

I have a Nikon and have acquired 50mm and 28mm lenses. I quickly noticed I can't focus to infinity on either lenses on my DSLR. After doing some research, it seems this is a known problem with Nikon bodies using M42 lenses.

It looks like there are 2 fixes for this. One is to buy an adapter with a correcting lens in it. The second is to modify (possibly permanently) the lens to fix the focus issue.

I've had a quick search and can't find an adapter with correcting lens. I don't mind modifying one of the lenses to see if it will work, but I can't find any info online for doing this. Does anyone have any experience in this area?

Thought I'd ask here rather than just taking the lens apart and breaking it.

Phil.
 
I discovered M42 lenses recently and have done quite a bit of research recently.

The problem with infinity focus is the rear element of the lens will be hitting your mirror. The only way to stop this from happening is to somehow stop the rear element from moving back into the camera body so far. Well, if you mount the lens further forward then the lens won't focus at all, unless you add an element to bring it back into focus. Hence the adaptor you've already mentioned. The problem with these is you can lose image quality.

I am not aware of any other way of modifying the lens to stop the rear element from moving back and hitting the mirror, sorry. :shrug: However you may find your answer on the manual focus forum.
 
i think the problem is with the lens being too far away from the mirror, it is not hitting it when taking a photo

cheers for the link, although the forum is not accepting new members at the moment... that is very silly
 
The real reason is simple - the M42 mount has a shorter register distance than the Nikon F-mount, by about 1mm. This means your lens sits 1mm too far away from the sensor causing the inability to focus to infinity.

Adapters with the correcting element can be found on Ebay last I checked, I even have one. Look for those Hong Kong based sellers.
 
waiting for delivery of one from hong kong which allows focusing to infinity and focus confirmation.
 
just ordered another one. had 'focus infinity' in the title so guessing its the right one
 
philxthomas said:
i think the problem is with the lens being too far away from the mirror, it is not hitting it when taking a photo

cheers for the link, although the forum is not accepting new members at the moment... that is very silly
Click to expand...

Ah weird! On Canons you get the opposite sometimes - the rear element hits the mirror :thinking: which was where I was coming from.

I managed to get on the forum just before they closed to new members, if you have any specific questions pm me and I'll ask for you - they're a knowledgeable lot (but very geeky!)
 
I bought a Canon A1, just to shoot M42 lenses...:gag:
but it came with a cough and its still being repaired...:banana:
so I went Nikon with an FM2...:D

I bought one of these http://cgi.ebay.co.uk/New-Kood-Nikon-to-M42

when the Canon thing is fixed, I'm gonna do a compare between this relatively expensive optical element ring and one with no element.
 
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