M42 - L39 adaptors

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Don't you lose some focussing ability? The register distance for m42 is about 45mm and that for m39 about 29mm, so the lens is focussing in the incorrect plane from its design - it would be like having a short lens tube on the lens and so not allow infinity focussing?

Interesting reference for flange focal distances on wikipedia here by the way
 
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Cuchulainn said:
Don't you lose some focussing ability? The register distance for m42 is about 45mm and that for m39 about 29mm, so the lens is focussing in the incorrect plane from its design - it would be like having a short lens tube on the lens and so not allow infinity focussing?

Interesting reference for flange focal distances on wikipedia here by the way
Click to expand...

I think you maybe right Brian, I had forgotten that the M42 camera would of course be SLR film and the L39 lens from a range finder and therefore the distance from lens to film plane would be different, the SLR being longer and would affect the the lens to closer focus objects, I think that would be the outcome.:thumbs::thumbsdown:
 
basically, with this combo, you lose the ability to focus to infinity, but it makes a gret close up lens - it's a little like the situation with using FDn lenses on a EF mount camera - unless you get an adaptor with a compensating lens in it, you're not going to get infinity focus, and if you DO get a adaptor with a lens in it, it'll degrade the picture quality, and probably end up working like a short teleconverter - my EF/FD adaptor is something like a 1.2x converter...
 
I have seen M42-M39 mounts that are really small, take it that would really screw up the focusing?

I think I'm just gonna buy a proper L39/LTM lens instead anyway because the m42 lenses are all quite bulky.
 
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