50mm ZM Sonnar f1.5 Focus Optimization

[nasmformyzombie]

I would like to get a ZM 50mm f1.5 Sonnar lens. I want it optimized for focus at f1.5. I've read online (so it must be true 🙄) that early samples of the lens were optimized for f2.8, later samples optimized for f1.5. If this is true, has Zeiss released serial number ranges to differentiate one variation from the other?

 

[Robert Lai]

Mine is optimized for f/2. You should test your actual lens to see where it is optimized. You should know that if you optimize the lens for f/1.5, then at f/2 and 2.8, you will be off focus as the depth of field is not deep enough to compensate.

With my lens, I know to move in closer to the subject about 2 cm at f/1.5, and move out about 2 cm when at f/2.8 to achieve focus.

 

[nasmformyzombie]

Mine is optimized for f/2...
With my lens, I know to move in closer to the subject about 2 cm at f/1.5, and move out about 2 cm when at f/2.8 to achieve focus.

It would seem you had your lens optimized for f2. I can see the logic in this, unless one wants to shoot primarily at f1.5. Correct?

 

[Robert Lai]

I didn't do anything to my lens. It came that way.

 

[thompsonks]

Robert is right – they vary a bit, and mine checks out at f2.2.

Kirk

 

[DNG]

This lens is made by Voigtlander/Cosina, I had one... I think it was optimized for f/1.5...

It is made to have a focus shift per the 1930's 5cm f/1.5 Sonnar, and was advertised as such, so the early ones were optimized for f/2.8 to give a slightly creamy effect at f/1.5 on a RF, not a Digital Mirrorless.

But, after 3m or so, the shift is within the DoF of f/1.5, so, 3m on, no worries when focusing at f/1.5 with the early ones. At that point the dof is deeper than the focus shift.

It would be nice if C/V had a S# list for each version. Maybe the head bartender can find out, being a large C/V dealer.

IT is a wonderful lens, here is a sample with Tri-X in Rodinal...
Leica M5, CV Zeiss ZM 50mm f/1.5

 

[pepeguitarra]

I think mine is optimize, period!

I think mine is optimize, period!

I focus at f1.5 and is perfect, I focus at every single other aperture and it is perfect. I have read and reread about the optimization, but I do not get it. So, I am not going to worry anymore.

 

[Vobluda]

I asked Zeiss about it last year providing them serial number of my lens and they replied that they don't have information on f stop optimization available.

This lens is made by Voigtlander/Cosina, I had one... I think it was optimized for f/1.5...

It is made to have a focus shift per the 1930's 5cm f/1.5 Sonnar, and was advertised as such, so the early ones were optimized for f/2.8 to give a slightly creamy effect at f/1.5 on a RF, not a Digital Mirrorless.

But, after 3m or so, the shift is within the DoF of f/1.5, so, 3m on, no worries when focusing at f/1.5 with the early ones. At that point the dof is deeper than the focus shift.

It would be nice if C/V had a S# list for each version. Maybe the head bartender can find out, being a large C/V dealer.

IT is a wonderful lens, here is a sample with Tri-X in Rodinal...
Leica M5, CV Zeiss ZM 50mm f/1.5

 

[David Hughes]

Hi,

By optimised do we mean working best or what? The idea of a lens with f/1.5 maximum aperture that doesn't quite work when using what it was made and bought for seems very wrong to me but that's only my silly* opinion.

And can you guess what we'd say if it was made in the old USSR?

Regards, David

* Copyright of this expression belongs to my young grand daughter...

 

[brbo]

By optimised do we mean working best or what?

It means the actual focus at the "optimized" f-stop will be the same as the rangefinder indicates.

At EVERY other f-stop the actual focus will drift further (at smaller than "optimized" f-stop) or closer (at wider than "optimized" stop).



I know you probably knew this already, but there is always a joker in almost every "sonnar focus shift" thread that muddies the water again and again. Yes, Sonnars have quite a lot of focus shift. Even the modern C Sonnar.

 

[Vobluda]

This is what Zeiss replied to Michael Reichmann of LuLA in 2007 based on his question after he tested the lens:

"Information about special features for dealers and users.

The C-SONNAR T* 1.5/50 ZM is a very special lens; based on a classical lens design concept from the 1930´s. The additional letter “C” in the name of the lens expresses this designation.

This lens design helps to achieve pictures with a special artistic touch. This lens ‘draws’ your subject in a fine, flattering manner and is therefore ideally suited for portraiture. It renders a sharpness that is slightly rounded, being less aggressive than in contemporary lens designs, but at the same time not soft in its rendition.

Many famous portraits of glamorous and prominent people during the 1930´s used this technique to great effect. These images are characterized by portraying the person in a shining, nearly celestial way. This effect is very well balanced and not exaggerated; therefore many viewers see it in a subconscious way. The trained observer, however, understands the underlining technique and enjoys the results.

This lens design exhibits some additional effects, which should be understood to achieve the maximum benefit from the C-Sonnar T* 1.5/50 ZM:

Because of the above mentioned classical characteristic of the lens the best focus position in the object space can not be kept exactly constant for all f-stop settings. The passionate photographer might notice a slightly closer best focus in his pictures than expected. When stopping down the lens to f/2.8 or smaller this effect is minimized, so the focus position will be as expected. In order to balance the performance at full speed and other f-stop settings the lens is adjusted with above described characteristic.

The special features of the C-SONNAR T* 1.5/50 ZM are best used in emotional, artistic, narrative images, portraits or atmospheric landscapes. For documentation or technical subjects CARL ZEISS recommends to stop down the lens at least to f/5.6 or to use the PLANAR T* 2/50 ZM lens."

Source:
https://luminous-landscape.com/zeiss-sonnar-50mm/

Hi,

By optimised do we mean working best or what? The idea of a lens with f/1.5 maximum aperture that doesn't quite work when using what it was made and bought for seems very wrong to me but that's only my silly* opinion.

And can you guess what we'd say if it was made in the old USSR?

Regards, David

* Copyright of this expression belongs to my young grand daughter...

 

[mfogiel]

You have to check the focus point yourself, or if you buy second hand, ask the owner. If you ask me, which version is better, I'd say: both.
Read this:
http://www.rangefinderforum.com/forums/showthread.php?t=51742&highlight=c+sonnar+comparison

 

[anerjee]

I got mine optimised by Zeiss oberkochen. They insisted that the Optimisation is only valid for a particular camera and lens combination.

So I sent my Zeiss ikon and c-Sonnar in, and the lens is awesome at 1.5. But it is off for my m-p, where it's best at about f/1.8 or f/2.

I would like to get a ZM 50mm f1.5 Sonnar lens. I want it optimized for focus at f1.5. I've read online (so it must be true 🙄) that early samples of the lens were optimized for f2.8, later samples optimized for f1.5. If this is true, has Zeiss released serial number ranges to differentiate one variation from the other?

 

[mcfingon]

I bought mine in 2013, and have found on my M3 and then M2 that it was optimized for f1.5. That is, the real focused distance agreed with what the rangefinder said. I worked out I could compensate for the focus shift of the Sonnar by using the small "pip" on the M3/M2 rangefinder patch as a distance amount to focus closer at apertures f2 to f2.8. I used the larger "pip" on the upper part of the rangefinder patch to move focus closer by that amount at apertures f5.6 and greater.

 

[Larry Cloetta]

I would like to get a ZM 50mm f1.5 Sonnar lens. I want it optimized for focus at f1.5. I've read online (so it must be true 🙄) that early samples of the lens were optimized for f2.8, later samples optimized for f1.5. If this is true, has Zeiss released serial number ranges to differentiate one variation from the other?

It's not true. The Sonnar design has inherent focus shift. Zeiss has said repeatedly, and will patiently reiterate to anyone who takes the trouble to ask, that every single C-Sonnar 1,5/50 they made was "optimized" at f2.8. Period.
You can either shoot at 2.8 and know that the point you are focusing on will be in focus, or, if choosing to shoot at f1.5 and minimum focus distance, you can focus, then lean forward a bare 2cm, 1 inch, or so, and your subject's eyes, or whatever, will be in focus in the resulting print. Easy.

The confusion results from the fact that they did offer to "optimize" any lens after the fact for f1.5, if the owner so desired. So those modified lenses are now out there. They are not "later production", they have just been modified from their original production specs and their existence has taken on a life of its own in the Internet hive mind. If buying used, at this point, the only way to really know what you have is to test it on a Lens Align or something similar, then shoot it accordingly. As others have said, even if you don't have a clue which "version" you have, factory original, or modified to show no focus shift at f1.5, in the vast majority of shooting situations the inherent focus shift makes no appreciable difference at all, is only going to be noticeable at close to minimum focus distance, and being swamped by other aspects of our technique. If the only thing you ever shoot is a model's eyes in full frontal aspect, from 1 meter away, then it matters. Outside of those situations, you'll rarely ever find a situation where the focus shift has caused you to be "off", even if you don't account for it with your technique.
Those who want to continue to see all this as some sort of an insurmountable problem will continue to do so, I suspect.
Personally, I love the lens.

 

[Sarcophilus Harrisii]

Could an original model 50mm f/1.5 from CZJ and/or Oberkochen be expected to broadly align with the observations discussed above apropo focus shift? From the Zeiss references one gathers, basically, yes?

I note that this discussion is in a Leica forum. At the risk of stating the obvious the lens was originally made in Contax mount for the Contax rangefinders, and it is, hence, to those earlier lenses that I refer.
Thanks in advance.
Brett

 

[brbo]

Could an original model 50mm f/1.5 from CZJ and/or Oberkochen be expected to broadly align with the observations discussed above apropo focus shift? From the Zeiss references one gathers, basically, yes?

Yes.

I have a post war Zeiss Oberkochen Sonnar and on my early Kiev II actual focus agrees best with the rangefinder between f2.8 and f4.

 

[Larry Cloetta]

Yes.

I have a post war Zeiss Oberkochen Sonnar and on my early Kiev II actual focus agrees best with the rangefinder between f2.8 and f4.

Off topic, somewhat, but how do you like the Kiev II? Do you have a Contax to compare it with, by any chance? Also, you mentioned 'early' Kiev II. The 'internet', again, feels that early Kiev IIs were better than the later ones, due to the use of original German parts and workers, and eBay prices reflect this.
My question is how early is early enough to be reasonably sure you are getting the supposed benefits of the original tooling, etc? 1954? 1953? Earlier?

Just curious, thanks.

 

[Sarcophilus Harrisii]

Yes.

I have a post war Zeiss Oberkochen Sonnar and on my early Kiev II actual focus agrees best with the rangefinder between f2.8 and f4.

Thanks! I have the same lens myself, (and Contax II + Kiev4M), so, very helpful.
Cheers
Brett

 

[brbo]

Off topic, somewhat, but how do you like the Kiev II? Do you have a Contax to compare it with, by any chance? Also, you mentioned 'early' Kiev II. The 'internet', again, feels that early Kiev IIs were better than the later ones, due to the use of original German parts and workers, and eBay prices reflect this.
My question is how early is early enough to be reasonably sure you are getting the supposed benefits of the original tooling, etc? 1954? 1953? Earlier?

Just curious, thanks.

Hmm... Mine is from 1955, so really not THAT "early". No idea how it compares to Contax II or later Kievs. I got it because it was described as "fully working" and it came with a case and a Jupiter-8 from the same year and I thought the price was still ok (80 or 90 EUR). The shutter ribbon broke on first roll, but I sent it to Oleg and it's been trouble free since then.