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PostPosted: Tue Jun 15, 2010 7:27 am    Post subject: Reply with quote
LucisPictor wrote:




What is MFD of this Mir-24N version? According to this picture it is 0.8m. Am I wrong? For the 24M version it is 0.3m.


PostPosted: Tue Jun 15, 2010 9:32 am    Post subject: Reply with quote
dimitrygo wrote:
What is MFD of this Mir-24N version? According to this picture it is 0.8m. Am I wrong? For the 24M version it is 0.3m.

It makes sense if the optics are identical to the 24M. For infinity focus on the Nikon mount, the lens block would need to be moved closer to the camera than with an M42 mount, and this would increase the MFD.


PostPosted: Tue Jun 15, 2010 10:10 am    Post subject: Reply with quote
peterqd wrote:
It makes sense if the optics are identical to the 24M. For infinity focus on the Nikon mount, the lens block would need to be moved closer to the camera than with an M42 mount, and this would increase the MFD.

Not sure I understand. If you take some M42 lens and file it to fit Nikon mount, doesn't this preserve its MFD? Since the Nikon version of this Mir lens has it's own redesigned barrel and mount I would expect it to have the same MFD as M42 version.


PostPosted: Tue Jun 15, 2010 10:21 am    Post subject: Reply with quote
OK, think about using an M42 lens on a Nikon camera. The lens won't reach infinity focus because the optical block cannot get close enough to the film. You would need to adjust the optical block closer to the film when the lens is at the infinity stop. Therefore it will still be closer to the film at the MFD stop and it will focus on a point further away than indicated on the dial, let's say 0.8m instead of 0.3m.

If you built a new body with a Nikon mount using this same optical block, you would need to increase the amount of turn of the focus dial to move the optics further from the film in order to focus on 0.3m (like using an extension ring).


PostPosted: Tue Jun 15, 2010 10:41 am    Post subject: Reply with quote
dimitrygo wrote:
LucisPictor wrote:




What is MFD of this Mir-24N version? According to this picture it is 0.8m. Am I wrong? For the 24M version it is 0.3m.


I've seen a vlaue of 0.2 m quoted as the MFD for a Mir 24N - sorry I can't remember where. All the pictures I've seen of this lens, together with the one copy I owned, have shown 0.24 m as the smallest number on the focus scale. Pehaps Carsten's copy is different. However 0.24 m ~ 0.8 feet. Coincidence ?


PostPosted: Tue Jun 15, 2010 10:53 am    Post subject: Reply with quote
peterqd wrote:
OK, think about using an M42 lens on a Nikon camera. The lens won't reach infinity focus because the optical block cannot get close enough to the film. You would need to adjust the optical block closer to the film when the lens is at the infinity stop. Therefore it will still be closer to the film at the MFD stop and it will focus on a point further away than indicated on the dial, let's say 0.8m instead of 0.3m.

If you built a new body with a Nikon mount using this same optical block, you would need to increase the amount of turn of the focus dial to move the optics further from the film in order to focus on 0.3m (like using an extension ring).


In order to reach infinity focus the lens block should be at some specific distance from the film plane regardless of the mount. The same is valid for MFD. Once again, if you take M42 lens, file its mount and attach to Nikon body you get both infinity and MFD. This is of course if there are no technical obstacles like protruding rear element. In the latter case there is a need to change the optical formula and this can affect MFD among other parameters.


PostPosted: Tue Jun 15, 2010 11:14 am    Post subject: Reply with quote
sichko wrote:
I've seen a vlaue of 0.2 m quoted as the MFD for a Mir 24N - sorry I can't remember where. All the pictures I've seen of this lens, together with the one copy I owned, have shown 0.24 m as the smallest number on the focus scale. Pehaps Carsten's copy is different. However 0.24 m ~ 0.8 feet. Coincidence ?

The marking on the M42 lens is 0.3m, but the ring turns a bit below this so in fact it can be 0.24m.

I see now, the problem is in the picture - the distance scale is partially covered, you can see it more clearly here:

And here is hardly seen 0.24m MFD


PostPosted: Tue Jun 15, 2010 12:23 pm    Post subject: Reply with quote
dimitrygo wrote:
In order to reach infinity focus the lens block should be at some specific distance from the film plane regardless of the mount. The same is valid for MFD. Once again, if you take M42 lens, file its mount and attach to Nikon body you get both infinity and MFD. This is of course if there are no technical obstacles like protruding rear element. In the latter case there is a need to change the optical formula and this can affect MFD among other parameters.

Yes, I agree with you if you file the mount down. I meant if you adjust the infinity position of the lens block to focus past infinity, then the distances engraved on the barrel become incorrect. But anyway, I see now this is academic! Smile


PostPosted: Tue Jun 15, 2010 2:48 pm    Post subject: Reply with quote
dimitrygo wrote:



hi dimitrygo,
is that an M42 screw mount version with an M42 to nikon adapter attached ?


PostPosted: Tue Jun 15, 2010 3:58 pm    Post subject: Reply with quote
kopimorning wrote:
dimitrygo wrote:



hi dimitrygo,
is that an M42 screw mount version with an M42 to nikon adapter attached ?

No, this is a Nikon version. M42 verison can be found here
http://www.zenit.istra.ru/archive/lenses/mir-24.html


PostPosted: Wed Jun 16, 2010 2:14 pm    Post subject: Reply with quote
dimitrygo wrote:

No, this is a Nikon version.


cool ... there's no infinity focus issue then, right?


speaking of which, where's the MIR vs Leica comparison? can't wait


PostPosted: Wed Jun 16, 2010 3:46 pm    Post subject: Reply with quote
kopimorning wrote:
dimitrygo wrote:

No, this is a Nikon version.


cool ... there's no infinity focus issue then, right?


On a Nikon body you will get both MFD and infinity. The same is for a Canon, Pentax and Sony bodies.


PostPosted: Wed Jun 16, 2010 6:22 pm    Post subject: Reply with quote
sichko wrote:
... the one copy I owned, have shown 0.24 m as the smallest number on the focus scale. Pehaps Carsten's copy is different.


Nope, my copy also shows 0.24m, you just can't see it in the photo.
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