ZM Planar for B&W?

[Roger Hicks]

If the lens is optimized for f/1.5, just focus at f/1.5. No compensation needed.

At f/2.8 or f/4, lean BACK a few inches.

Go to http://www.rogerandfrances.com/subscription/ps firstlook sonnar 50.html and scroll about half way down to see a 'worked example' of a lens optimized for f/1.5.

For a lens optimized for f/2.8, just focus at f/2.8. No compensation needed. At f/1.5, lean FORWARDS a few inches.

Cheers,

R.

 

[drasko]

If the lens is optimized for f/1.5, just focus at f/1.5. No compensation needed.

At f/2.8 or f/4, lean BACK a few inches.

Go to http://www.rogerandfrances.com/subscription/ps firstlook sonnar 50.html and scroll about half way down to see a 'worked example' of a lens optimized for f/1.5.

For a lens optimized for f/2.8, just focus at f/2.8. No compensation needed. At f/1.5, lean FORWARDS a few inches.

Cheers,

R.

Hi Roger,
thanks a million.

I just figured it out from the wonderful Marke's experiments : http://www.rangefinderforum.com/forums/showthread.php?t=51742&highlight=mfogiel+zeiss+sonnar

I actually did not have idea that there are 2 kinds of Sonnars ("older" 2.8 optimized and "newer" 1.5 optimized).

I actually have Jupiter 8 which is Sonnar copy, but it seems to exhibit focus shift when wide open. Since it dates from the '60 I guess that it is copy made for 2.8 optimization...

Thanks again for this clarification.

BR,
Drasko

 

[EdwardKaraa]

Unless it's just changed, and I mean JUST - it's not true. I'e. Sonnar 50 is still calibrated to 2.8. Reason I say this is - about a month ago I emailed Zeiss with this specific question and thats what they told me ( I think I posted it here some place). They say that they still make Sonnar 50 calibrated to 2.8, but offer a recalibration for free to 1.5 while lens is still under warranty.
So, as I got this answer about a month ago, I'd imagine thats where things still are. Unless, of course Zeiss JUST changed that. Best way to find out - go to Zeiss site and email them with this question.

In fact, the ZM lenses are calibrated for the lens stopped down 2 stops. Even for lenses claimed to have no focus shift, they all have shift but some less than others, the Sonnar being at one extreme. The 35/2 has bit less but still quite substantial. It is calibrated for f/4. The Planar shift seem to be negligible in my experience.