Got a great deal on a Zeiss C Sonnar ... struggling with focus shift

P

PhotoGog

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I recently got a great deal on a mint Zeiss C Sonnar 50/1.5. Ran 3 x rolls of Ektar through my M6 to see what it can do. Have to admit, only half the frames are in acceptable focus. Of course, I am fully aware of the focus shift issues with this lens and read most of the threads on RFF ... but still. The shots that are in focus definitely have that Sonnar WOW factor and yet ... half of each roll seems wasted. First inclination was to flip the lens at a profit given I got such a good deal. But then again, other lenses in the same focal length render like any other (might as well shoot with my Nikon SLR). What to do? Keen to promise to myself to shoot it for six months and reevaluate my feelings about the lens then. God knows I have made some GAS inspired rash decisions in ten past. How to master this lens?!
6470d779a10944c5cecdc2ffa96b8754.jpg
 
If you got it cheap maybe use the rest of the money to have it serviced/adjusted. Maybe it was dropped during its lifetime and needs to be readjusted to be brought within factory specifications. I have a zuiko 35f2 that I was not very happy with. Serviced by Luton cameras and now it performs much better.
 
1. Shoot f2.8 if you can. That may be the sweet spot.
2. Do your own focus shift tests. You can find mine by searching Zeiss C Sonnar focus shift Richard G site:rangefinderforum.com
3. Relax a little. My 50 Summicron back focussed at f2 by 2cm close in for the first 25 years I used it with film. Hardly noticed. Many C Sonnar owners who’ve never heard of focus shift are probably just as happy as I was with my Summicron. You’ve probably been concentrating on ‘bokeh’ shots. The C Sonnar is still magic at f5.6.
4. Don’t give up yet.
 
I use adapted opton sonnar 50/1.5 that I believe it behaves like C-Sonnar.

I use it mostly from f2.8 to smaller aperture & hardly notice focus shift, yet still get that sonnar signature. Only worry about shift at f1.5 - f2 & compensate the front focus by moving focus patch about 1mm to the farther distance.

In your case, I think it's best to do your own test shot to see in which aperture it show the focus shift, then learn to compensate; also notice which aperture start to give acceptable focus so you dont need to worry when using that setting.
 
I have Jupiter-3 which I shimmed by my self. I can't recall someone complaining about focus shift with this lens. My last Cron to try is not in use now. It is same optical formula, but no anoying 1/3 clicks, no clicks at all, with TTL camera it is better.
 
Ko.Fe. said:
.. but no anoying 1/3 clicks, no clicks at all, with TTL camera it is better.
Click to expand...


Aaaahh the internet:
"I am trying to fix a Canon. Please help.."
"I have a Nikon. it´s much better"


Does a Jupiter have the T coating? The famous Zeiss 3D pop? No?



Why gloat about another lens when this guy is trying to fix his ?
 
Richard G said:
1. Shoot f2.8 if you can. That may be the sweet spot.
2. Do your own focus shift tests. You can find mine by searching Zeiss C Sonnar focus shift Richard G site:rangefinderforum.com
3. Relax a little. My 50 Summicron back focussed at f2 by 2cm close in for the first 25 years I used it with film. Hardly noticed. Many C Sonnar owners who’ve never heard of focus shift are probably just as happy as I was with my Summicron. You’ve probably been concentrating on ‘bokeh’ shots. The C Sonnar is still magic at f5.6.
4. Don’t give up yet.
Click to expand...



Thanks for the advice. Will definitely dedicate a roll to my own test. I did in fact shoot the lens at all apertures but found that even at f/8 on Ektar it was not as sharp for landscapes as my CV 35/2.5. Perhaps user error (my own shake or too low a shutter speed). Will test it and see what aperture is most accurate in my copy for portraits.
 
Another tip passed on from Roger Hicks in this forum is to focus on the nearest part of the shot you want in focus if you're stopped down at f8 for instance. The focus shift of the Sonnar will make the depth of field appear to be all behind the focus point. I'd also get familiar where your particular M6 body and your C Sonnar give you the best agreement of focus. My 2013 model C Sonnar and my 1986 M6 give a very good agreement at f1.5, as shown in the shot below.
U51008I1543062174.SEQ.0.jpg

Leica M6 ZM Sonnar 50 at f1.5 1/1000th Delta 100 in Xtol
John Mc
 
I agree with the others about testing. They all shift but you need to know how your sample behaves in order to control it. You'll quickly find the sweet spot.

If your primary use will be wide open for portraits it would be a good idea to have Zeiss optimize the lens for wide open use (assuming yours is currently optimized for f2.8 that is) and you'll be good to go.

It's a good lens but does require practice and attention due to the shift. Early on I figured I would have mine adjusted for 1.5 but once I tested and got the hang of my sample (2.8 optimized) I decided against it and have been happy with the performance.
 
PunkFunkDunk said:
Thanks for the advice. Will definitely dedicate a roll to my own test. I did in fact shoot the lens at all apertures but found that even at f/8 on Ektar it was not as sharp for landscapes as my CV 35/2.5. Perhaps user error (my own shake or too low a shutter speed). Will test it and see what aperture is most accurate in my copy for portraits.
Click to expand...


If you are shooting landscapes, architecture and objects then a Plannar or Heliar could do a better job. Those are not very expensive lens and you could add to your basic equipment.

My advice is get another lens and use both, each for a dedicated subject. Then you will find the strengths and weaknesses of the Sonnar.
Another ideas: yours may be adjusted for 1.5. Later production was adjusted for 2.0 or 2.8.

Did you check your rangefinder? Is it adjusted?
 
It is possible the problem involves a miss-alignment for how your camera's focus cam mates with this lens. It is possible to find a compromise setting such that all your lenses align properly.

Or, ss p.giannakis mentioned, it is could be the lens mechanism needs adjustment.

The Flickr thread linked by moda001 indicates in 2.8 optimized versions focus shift only affects close subject differences. Of course if your lens is optimized for f 1.5, the shift effect would occur longer subject differences. In any case it should focus properly at some distance.

My C Sonnar 50/1.5 was optimized for f 2.8. At longer subject distances (wide DOF) using apertures 4 or narrower the rendering was crisp with high perceived contrast. But at 2.8 and wider the same scene, using the exact same focus, rendered with much less contrast. Everything seemed softer.

If you do testing, use a tripod and a focus target.
 
Where are you? If you are in LA you can swing by my gallery and we can test it on my M240 to see where it actually focuses at all apertures.
I have the same lens, but have no issues with it in use. For half of your roll to be OOF it seems something is up. Perhaps that is why the lens was sold so cheap?
 
I either shoot mine wide open or closed down to f8 or f11. So I had DAG adjust mine to focus spot on at f1.5.

I love it now but I rarely shoot landscapes with it. The Zeiss Planar or Biogon are much, much better lenses for this type of work.


EDIT - In fact, if you are looking for ultimate sharp focus at closer distances and wide open then some could argue that the ZM Sonnar C 50/1.5 isn't the right lens to start with.
 
I just got a sonnar C a couple weeks ago and ran a test on my first roll. I did the little statue guy at just about min focal distance and lined up the "needle" I can see slight focus shift on my copy, but I guess for what I bought it for (people) it really doesn't bother me all that much. Maybe I am just not that picky since I look through the magnum contact sheets and realize some of my favorite photos are not tack sharp. I have a variety of 50's at this point though, and this one is specific to when I know I am shooting primarily people. My all purpose 50 is either a v1 or v2 cron. I did get a Chiyoda Kogaku 50 1.8 which I am testing as well. So far it look fantastic. I'll post a couple from my test roll including my "focus shift" test. Shot order is f1.5/2/2.8/4
Kentmere 400 in Rodinal 1+25
44-23.jpg by Chris Coppola, on Flickr44-24.jpg by Chris Coppola, on Flickr44-25.jpg by Chris Coppola, on Flickr44-26.jpg by Chris Coppola, on Flickr

and a couple randoms shot at f2 I believe to see how it works in real use for
me

44-6.jpg by Chris Coppola, on Flickr44-15.jpg by Chris Coppola, on Flickr44-28.jpg by Chris Coppola, on Flickr
 
Tip: slavishly following the RF is not helpful on any Sonnar. To hit focus below f/2.8, you will turn the focusing ring to the left by a hair (toward infinity). It will be the smallest perceptible motion you can make with the focusing ring (as in you just feel it move).

Your only other option is to recollimate the lens for f/1.5, which will royally screw up your focus at f/2-2.8-4 (and possibly 5.6) unless you are committed to hiking the focus in the other direction. I think it's better to work with it set at 2.8; this is the same way every single fast lens is anyway (the 75/1.4 is exactly the same thing) - they all front-focus at wide apertures.

And in terms of affect, front-focus is almost always preferable to back focus.

I have used pretty much every version of the Sonnar that you can jam on a Leica, and they all behave pretty much identically. Sonnars are also far easier to learn on a digital body, since you can instantly see what your focusing technique is doing.

D
 
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