After the thrill is gone for a period of time, again I feel the urge for affordable (and told-to-be brilliant) M42 MF lenses like Jupiter and Tair. The register difference of Nikon is more than the original M42, so no infinity focus unless an adapter with glass is bought (which I'd rather avoid to be able to see the real performance of the original glass). The question is, where does the problem with "infinity focus" begins? I mean from which distance to infinity?
Kind regards,
Serkan
There is no general value for this, since this depents on the focal length ...
a 50mm lens moves its optical group only a few mm forward in order to
focus from infinity to MFD (usually around 50cm).
A better approach would be to try lenses (like the Tamron Adaptall-2) that
already come with a register distance that is large enough .
You could (of course) also get a Canon EOS body for this.
Roughly speaking, shorter focal length lenses will have more of a "problem" than longer ones. You can try
this calculator for an indication. Zero the close up lens dioptre value and plug in just the focal length and extension. The rest don't matter if you're not looking at minimum focus. As example, if you have 2mm extension on 50mm lens, you're down to 1.3m! But 2mm extension at 300mm works out to 45m.
Otherwise, learn to love macro <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
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Thanks... So, for a Tair 11a (135mm), it is then ~17,7 meters... I entered 1,04mm in the field "extension" as it is the register difference in mm between F-mount and M42. Is that correct?
11-22-2010, 07:29 PM
(This post was last modified: 11-22-2010, 07:31 PM by Rainer.)
[quote name='PuxaVida' timestamp='1290453449' post='4335']
I entered 1,04mm in the field "extension" as it is the register difference in mm between F-mount and M42. Is that correct?
[/quote]
Well, the register distance for Nikon-F is 46.5 ... M42 is 45.5 ... so in principle the difference is 1mm ... but
the adapter itself will also have a certain thickness ... I must admit I have not seen a M42 to Nikon so far.
So, if this adapter has indeed its own thickness and does not completely sink into the Nikon mount, you
will have to add adapter thickness too ... and that will likely destroy all your plans.
Regarding you concerns with the Adaptall-2 glass ... if you stay with the "SP" lenses, you are likely
on the save side.
[quote name='PuxaVida' timestamp='1290437762' post='4329']
After the thrill is gone for a period of time, again I feel the urge for affordable (and told-to-be brilliant) M42 MF lenses like Jupiter and Tair. The register difference of Nikon is more than the original M42, so no infinity focus unless an adapter with glass is bought (which I'd rather avoid to be able to see the real performance of the original glass). The question is, where does the problem with "infinity focus" begins? I mean from which distance to infinity?
Kind regards,
Serkan
[/quote]
You may be able to modifiy the lenses you are after. I have a Carl Zeiss Jenna DDR 135mm 3.5 that I just had to modify so that it would turn further on focusing bringing the whole lens group closer to the sensor. Works perfectly on my Nikon D90. I guess this is more likely to be possible on longer lenses though I reckon it might work on the Jupiter as well.
It was really easy to do on the CZ Jenna but I have no idea how easy it is with other lenses.
What kind of modification have you done exactly to adjust the focusing ring?
[quote name='PuxaVida' timestamp='1290498475' post='4348']
What kind of modification have you done exactly to adjust the focusing ring?
[/quote]
I can't really remeber to be honest, I had taken it apart to clean and re-grease and I think part of the dissembly involved ensuring you kept the infinity focus point in the right place. I then realised I could just change it so that it worked on my nikon to infinity, can't remeber how exactly.
I was following this guide for dissembly
http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/
/edit having a quite read it sounds like it had something to do with the infinty adjustment screw...
Thanks for the link, I'll check it...
Serkan
