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Old 11-29-2019   #41
Huss
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The Zeiss Sonnar ZM 50 1.5 is notorious for focus shift and that is way more expensive than 7A lenses.
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Old 11-29-2019   #42
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Originally Posted by Ko.Fe. View Post
Free or not, but where is 21 f1.5? Or 35 f1.4. Is it arrested development now?
In a re-education camp.

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Originally Posted by Huss View Post
The Zeiss Sonnar ZM 50 1.5 is notorious for focus shift and that is way more expensive than 7A lenses.
That's the nature of the Sonnar design and unavoidable. Take the Nikkor 50/1.4 LTM; focus is optimized for ƒ/1.4 shifting steadily as you stop down. In the case of the 1,5/50 ZM, Zeiss optimized focus for ƒ/2,8 where it's spot-on. Buy it new and they will re-adjust it gratis, optimizing focus for ƒ/1,5 if that's your preference.
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Old 11-30-2019   #43
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Originally Posted by dourbalistar View Post
Absent a digital Leica M, is there an easy way to calibrate the focus on the 7A lenses? Or are all the solutions a bit kludgy, like using an appropriately sized piece of ground glass and a loupe with the back door open?
http://rick_oleson.tripod.com/index-123.html
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Old 11-30-2019   #44
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How would any lens with noticeable focus shift be useable on a RF? Perhaps if the amount of focus shift was so small that it was less than the DoF increase from stopping down?
Seems that lens would work best on a TTL type viewfinder camera.
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Old 11-30-2019   #45
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....The only justification for buying such a lens is hidden in a clever marketing move - if you pay 300$, you can get the CREATIVE opportunity to fiddle with close focus and infinity.
Incorrect. The rfs in all my Ms are correctly calibrated. And yet I have two lenses that are not spot on. My ZM 50 1.5 front focuses, while my CV 35 1.2 v2 back focuses. I take this into account when I use them but I would absolutely love it if I can bring them into correct focus calibration the way I can do with 7A lenses.
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Old 12-01-2019   #46
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Sorry Huss, you are right. I stand corrected. The main issue are not the lenses, but that primitive and obsolete tool we use for focusing them, the rangefinder.
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Old 12-01-2019   #47
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Sorry Huss, you are right. I stand corrected. The main issue are not the lenses, but that primitive and obsolete tool we use for focusing them, the rangefinder.


But the rangefinder is so good for focusing wides!
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Old 12-09-2019   #48
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Originally Posted by zuiko85 View Post
How would any lens with noticeable focus shift be useable on a RF? Perhaps if the amount of focus shift was so small that it was less than the DoF increase from stopping down?
Seems that lens would work best on a TTL type viewfinder camera.
With a lens like the Zeiss 50/1.5 Sonnar, as james.liam above mentioned, the manufacturer traditionally calibrated the optimum RF focusing a couple stops down from wide open. This meant that at f/2 the lens slightly front focused, but might still be reasonably within DOF (and on film, maybe not so noticeable), while at f/4 it would be slightly back focused, but the increased DOF at f/4 would hopefully cover much of that error. Shooting wide open would have the greatest focus error, but the lens was already pretty glowy and the SA would mask some of this. Again, on film it was likely less noticeable. My understanding is now the ZM50/1.5 is RF calibrated for wide open use, given this is now the popular way to use the lens on digital. To compensate for focus shift, one would have to intentionally guesstimate intentional front focus when shooting at f/2, 2.8 and f/4 before DOF masks the shift.

I also have the 7A 50/1.1 and fine-tuned the RF cam for correct RF focus with my camera at f/1.4, the point at which it sharpens up a bit yet still has nice SA glow. TBH, I have not checked infinity. I primarily use the lens at nearer distances as a character lens. It takes stopping down to f/11-16 to really bring up the edges for more technical applications. Instead I rather use a more capable design for such applications (i.e. ZM50/2 or 50 Lux ASPH).
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Old 12-09-2019   #49
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...........
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Old 12-09-2019   #50
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I just received my 75! Perfectly calibrated out of the box! Damn hard to nail focus without a magnifier though!
Does it focus past infinity?
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Old 12-09-2019   #51
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Surprisingly no. Its the best calibrated out of the box of all my 7a lenses
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Old 12-09-2019   #52
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Surprisingly no. Its the best calibrated out of the box of all my 7a lenses
Nice, congrats! Maybe some at 7A saw this thread..
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