50mm ZM Sonnar f1.5 Focus Optimization

[Larry Cloetta]

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.

Thanks. Bought a nice Jupiter 12 for my Contax IIa knowing full well that it would not fit the IIa, but forgetting that fact for the length of time it took to hit the 'buy it now' button.
Hardly worth the time and effort it takes to sell it, so was thinking I should just get a Kiev to go with it. And wondering/knowing what my chances were of getting one which actually was 'fully functioning'. As if I needed yet again another body.
Anyway, thanks again.

 

[David Hughes]

Thanks folks for the explanation of optimised.

As for the Contax II and Kiev 2a, they feel the same to me and look the same, more or less. And when they fail, expect problems but nothing that can't be cured with money and patience.

FWIW, my Contax II has a Kiev shutter mechanism fitted after the proper one was just worn out...

Regards, David

 

[Larry Cloetta]

Thanks folks for the explanation of optimised.

As for the Contax II and Kiev 2a, they feel the same to me and look the same, more or less.

Regards, David

Thanks, David.

 

[pepeguitarra]

Optimization, maybe I get it now!

Optimization, maybe I get it now!

Three ideas I bring:

1) Isn't optimization what Leica does with their lenses? I used them mostly wide open. Is that different from SWEET SPOT?, which in many lenses is about f8?

2) Let me see if I understand focus shift:
If I have my camera with the Zeiss 50/15 on a tripod and focus perfectly on a model's eyes wide open (f1.5) and shoot, I should get the eyes on focus.
Then, if I touch only the lens aperture ring and move it to f2 (without touching the focus ring), will the eyes be in focus? If yes, there is no focus shift. If the eyes are not in focus, is there a focus shift, correct?

Please confirm.

3) I bought a CV Nokton 35/1.2 ASPH 2 from a member here, almost brand new. When on my Leica M9, it always front focused. I asked the previous owner and he said that no, he used it on a Sony Alpha.
Sent it to Youxin, he said the lens needed collimation and recommended DAG. I sent it to DAG and he collimated it and the lens is now more than perfect and I am very happy with it (optimized for Leica?). That may be the reason I see so many of these lenses for sale. Apparently the lens was made for Voigtlanders camaras, not Leicas. I guess there is a difference in focal distance. Is this true? Is this related to shifting? I do not think so.

Thanks for the educational moment.

 

[brbo]

No.
Yes.
No.

 

[Larry Cloetta]

Three ideas I bring:

1) Isn't optimization what Leica does with their lenses? I used them mostly wide open. Is that different from SWEET SPOT?, which in many lenses is about f8?

2) Let me see if I understand focus shift:
If I have my camera with the Zeiss 50/15 on a tripod and focus perfectly on a model's eyes wide open (f1.5) and shoot, I should get the eyes on focus.
Then, if I touch only the lens aperture ring and move it to f2 (without touching the focus ring), will the eyes be in focus? If yes, there is no focus shift. If the eyes are not in focus, is there a focus shift, correct?

Please confirm.

Your theoretical example is correct. That would be an example of focus shift, in a lens design which has inherent focus shift, such as the Zeiss 1,5/50 of any vintage.
HOWEVER, the modern Zeiss C-Sonnar 1,5/50 as it came from the factory originally, would not work that way. It came from the factory such that the eyes in your example would be in focus with the aperture set at f2.8, not F1.5. If you set the aperture at f1.5, following the method you outlined, and focused on the model's eyes, at minimum focus distance of 1 meter, in the resulting negative it would be the tip of the model's nose, more or less, which would be in focus. You won't have missed focus by much, but it would be off.
If she were 15 feet away, and you focused on her eyes, both her eyes and nose, and more would be in focus, and you'd not be aware of any "problem" with focus shift.
If you had one of the C-Sonnars that had been modified to be spot on at f1.5, instead of f2.8, the results would be different accordingly, but it's easy to compensate either way in those cases (rare for some of us) where you are trying to nail critical focus at minimum focus distance wide open.
If the model and photographer both move 1 cm, either in or out, after focussing, then all this goes completely out the window anyway. And, of course, that never happens.

 

[Larry Cloetta]

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.

I had noticed that you had responded to this thread earlier, with this post. This goes right to the point. Unless you sit around like Lloyd Chambers with the camera on a tripod shooting pictures of test charts and dolls at minimum focus distance, it is unlikely that one would ever notice that there is, in fact, focus shift. It's there if you look for it, but it rarely has a bearing on most photos that most people shoot.
I've seen posts from people who say they shoot mostly 'street' who worry about focus shift with this lens. LOL.
You are right not to worry anymore..

 

[pepeguitarra]

Examples

Examples

Well, I found some shots taken by me with the M9 and the Zeiss Sonnar 50/1.5 ZM:

At min. distance wide open:

CZeissSonnar50mmf1.5-M9-MiMandarina1 by Palenquero Photography, on Flickr

CZeissSonnar50mmf1.5-M9-ParkGrass1 by Palenquero Photography, on Flickr


ZeissSonnar50mmf1.5ZM-Hook2 by Palenquero Photography, on Flickr


M8

Zeiss Sonnar 50mm f1.5 @ f1.5 on a Leica M8 by Palenquero Photography, on Flickr


Focus on the right eye

Don Henry by Palenquero Photography, on Flickr


At f2- Min distance


Zeiss Sonnar 50mm f1.5 @ f2 by Palenquero Photography, on Flickr


At f4 - min. distance


Zeiss Sonnar 50mm f1.5 @ f4 on a Leica M8 by Palenquero Photography, on Flickr


Zeiss Sonnar 50mm f1.5 @ f4 on a Leica M8 by Palenquero Photography, on Flickr


M9-CZS50mmf1.5-Hybiscus333-1 by Palenquero Photography, on Flickr


I think this is a great lens and it is my second fastest lens (first is the Nikkor SC 50/1.4), third the summicrons.

 

[DNG]

@Pepe

On Q3...
When you use a camera with liveView LCD, you are not depending on a RF to focus, you are focusing TTL, so you will override any focus shift...

With TTL focusing, focus shift is moot IF you refocus at any f/stop. (which is a good habit anyway...just to be sure what you want in focus IS in focus).

Don't most shooters refocus with an f/stop change with fast lenses focused 1 or 2 stops down, then you decide to open up, you refocus?

BTW, Great set of photos....

 

[pepeguitarra]

@Pepe

On Q3...
When you use a camera with liveView LCD, you are not depending on a RF to focus, you are focusing TTL, so you will override any focus shift...

With TTL focusing, focus shift is moot IF you refocus at any f/stop. (which is a good habit anyway...just to be sure what you want in focus IS in focus).

Don't most shooters refocus with an f/stop change with fast lenses focused 1 or 2 stops down, then you decide to open up, you refocus?

BTW, Great set of photos....

Excellent advise, I refocus and refocus and refocus at all times. Since I tend to use the lens wide open most of the time, I have to make sure the thin dof hits the target.

 

[neonart]

I bought mine in 2014, never did a thing to it and seemed to work perfectly fine. Even used it on assignments and had no issues. Not once did I find the "focus shift" to be an issue. YMMV

My only complaint with the sonar was the .9 focus distance. I would often use the Planar day to day, and the Sonnar for low light and more creative stuff. Eventually I sold them and got a Lux50 which kinda merged both, but to this day I miss the Sonnar ALOT!

I'd get one new from a reputable dealer or used from KEH or some place where you can return it. If it works great if not you can decide weather to have it optimized or return it.