ZM Sonnar - to calibrate or not?

[Archiver]

My 50/1.5 Sonnar came with the standard f2.8 calibration, and the focus shift at f1.5 bugs me every now and again. I shoot it at f1.5 a lot and I still haven't got the hang of exactly how much to compensate.

If I was going to use this as a general purpose lens, would the increased depth of field at f4 and above compensate for optimizing it for f1.5? Is it worth getting this lens calibrated for f1.5 at all? I'd appreciate some thoughts and experiences with this.

Thanks!

 

[mfogiel]

Personally, I believe that the C Sonnar is so good at what it does at f 2.8-4.0, that calibrating it for wide open makes only sense, if you really are a bokeh freak. In my opinion, you can adjust the focus with the wide open calibrated version, but it surely excludes any fast walkaround shooting. Read this report:
http://www.rangefinderforum.com/forums/showthread.php?t=51742
I have solved the problem by keeping both versions, and when I need a single do all lens of similar speed, I use the pre asph Summilux 50.

 

[Archiver]

Haha, the obvious solution: buy another Sonnar and a Summilux! I love it!

...noooo, that's not what I came here for! 😀

 

[Roger Hicks]

Mine is set for f/1,5. By f/5.6 d-o-f covers the problem. It matters only at f/2 to f/4, and then, only at close distances. On the rare occasions I use it close up at those apertures, I just lean back 3 inches...

I'm generally in more of a hurry at f/1.5 (quick shots in low light), or I'm shooting at f/5.6 to f/8 and it doesn't matter. For me, f/1.5 calibration makes MUCH more sense.

Cheers,

R.

 

[jawarden]

My 50/1.5 Sonnar came with the standard f2.8 calibration, and the focus shift at f1.5 bugs me every now and again. I shoot it at f1.5 a lot and I still haven't got the hang of exactly how much to compensate.

I think you answered your own question up there. Zeiss offers the calibration for people like you who use the lens at 1.5 a lot.

do it do it do it 🙂

 

[brbo]

I had it calibrated for f1.5. If I can't have it optimized for the whole range, I'd rather have it optimized for scenarios where focusing precision or lack of it is more pronounced.

 

[kosta_g]

you don't have to be a bokeh freak to want it calibrated to 1.5. it's still bokeh-full at 2.8 anyway. plus why bother with a lens that has 1.5 aperture unless you want to utilise it's unique rendering at that aperture anyway? they all look close (the same) by 5.6 anyway! (?)

 

[Roger Hicks]

Not sure about God, but Dr. Hubert Nasse, who comes pretty close to God in the Zeiss lens design firmament, pretty much shrugged and said something to the effect of, "We thought most people would prefer to compensate when shooting wide open, but I'm not sure we were right. That's why it can be set either way."

Cheers,

R.

 

[brbo]

What were old Sonnar design lenses (from Zeiss, Canon, Nikon...) optimized for? Were Sonnars from Zeiss always optimized for "mid-aperture" or has Zeiss "found God" only recently?

 

[Never Satisfied]

Hello all! I'm looking at buying a 2nd hand Sonnar and really want one optimized for f1.5, is there a serial number that Zeiss started to optimize all Sonnars for f1.5, or is it hit and miss?
Thanks Andrew.
Please PM me if you have a 50mm Sonnar optimized for f1.5 for sale.

 

[rxmd]

Can you change the calibration yourself?

 

[mod2001]

Can you change the calibration yourself?

yes, found this in the Flickr-group:

I purchased the f1.5 version, anyway i managed to get both optimizations by taking out one shim. Then i just have to move the rear element by -90º and voila, 1.5 or 2.8!!!

Gap the adjustment is made by inserting 2 or three shims between the rear element and the front one.

2 shims= f2.8 opt.
3 shims =f1.5 opt.

So i took away one shim and left loose the rear element, so when i want to shoot at f1.5 i only have to unscrew the rear element by 1/4 a turn or -90º that way i compensate the lack of the third shim.
Then i nail focus at f1.5!

Of course this trick can be undone anytime.

Yogi

 

[3dit0r]

Sorry to hijack, but I'm interested in this lens and obviously concerned by 'focus shift'.

I have a question though, my understanding of focus shift is that it occurs when you focus at one aperture, then shoot at another?

I gather though from these threads that this is not what is occurring with this lens, or everyone would just focus at the shooting aperture?

Can anyone explain, please?

 

[Roger Hicks]

Sorry to hijack, but I'm interested in this lens and obviously concerned by 'focus shift'.

I have a question though, my understanding of focus shift is that it occurs when you focus at one aperture, then shoot at another?

I gather though from these threads that this is not what is occurring with this lens, or everyone would just focus at the shooting aperture?

Can anyone explain, please?

Bear in mind that you are focusing by proxy, via a mechanical linkage, and that the mechanical linkage takes no account of the aperture at which you are shooting.

Cheers,

R.

 

[Matus]

I have read a lot about this issue and keep wondering whether calibrating the lens at f/2.0 would not be optimal solution ... ?

 

[foolstop]

Well.
There are more ways to work around this focus shift issue.

With the 2.8 optimized version using the lens wide open:

1. lean forward for a few centimeters when shooting close subjects.
2. learn to throw the focus ring a little bit off set, especially for shooting subjects more than ten feet away.
3. forget about it.

Or you can try the ZM S version of the Sonnar with a "suitable mount".
After testing for more than a dozen, I found one that can focus sharply from 1.5 all the way to infinity.

Or you can send your ZM C Sonnar to Ziess for re-calibration.
With luck, I have mine back with good sharpness at 1.5 and 2.8 😛

Or you can keep more than one 🙂


http://www.flickr.com/photos/foolstop/sets/72157622622763571/

Cheers.
Foolstop
--------------------

 

[elmer3.5]

Hi, i had the same issues when shotting with fast lenses, but i learned how to optimize the sonnar in a glimpse!

Once fooling around with an old contax sonnar i realized that it´s set to 2.8, but if you unscrew by 90º the rear element you get the optimization at f1.5!

So when i bought a c-sonnar i tried the same... and touché, it works, so now i use both optimization in one lens.

Check the photograph there are two marks, the first with two nothces for 2.8 and the single one for 1.5 opt.
It´s made by moving 90º the rear element rim.

Bye!