Zeiss Sonnar

[tbarker13]

(apologies to anyone who already read this on the Leica User forum)

I just purchased a 50 Zeiss Sonnar to use as a softer portrait lens on my M8.

I asked Zeiss about their offer to adjust the lens to minimize the focus shift at f/1.5. They say it will take about 10 days to make the adjustment, once they receive the lens. And it is free as long as it is under warranty.
They said it would focus more accurately in the f/1.5-f/2.0 range. But that the shifting would be more pronounced below f/2.8.
From Zeiss:
"When you stop down to f/2.8 or smaller, there will be visible a slight focus shift, but sharpness will be covered within the depth-of-field. In practical use, after the adjustment the focus shift will not play an important role anymore."

What I am wondering is whether the adjustment would affect the character of the lens, bokeh, etc. I'm awaiting an answer from Zeiss on this.
But what do you guys think? Does the shifting feature have any impact on the way the lens draws? Aside from sharpness of focus, I mean.

 

[back alley]

don't know but very interested in the answer also.

not sure why zeiss didn't adjust for 1.5 in the first place.
joe

 

[tbarker13]

That's exactly what I am wondering. I'm trying to figure out what the trade-off is. If there is no negative impact, I can't see a reason not to have it adjusted.

 

[Tony C.]

This reply from Zeiss, to a revew at Luminous Landscape (see link below), provides some interesting insight:

C-Sonnar T* 1,5/50 ZM
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.

The above-mentioned review can be found here:

http://www.luminous-landscape.com/reviews/lenses/zeiss-m-mount.shtml

Regards,

Tony C.

 

[back alley]

tony, i've seen that before both here at a ll but it doesn't really answer my question considering what they told tim.

joe

 

[hth]

I get puzzled by the answer from Zeiss. If adjusting the lens so that it focuses more accurately in the f/1.5-f/2.0 range, means a trade-off with focus shift at f/2.8, but that is covered by the increased depth-of-field, so it would play no important role.

Then why not adjust the lens like this from beginning? To me it sounds better having a focus shift stopped down if it is covered by DOF, than having a focus shift wide open which is not covered by DOF. If I buy a fast lens, I would expect it to be sort of optimized for wide open performance.

Also, how does focus distance play into this? It should be more of a problem close-up?

/Håkan

 

[back alley]

I get puzzled by the answer from Zeiss. If adjusting the lens so that it focuses more accurately in the f/1.5-f/2.0 range, means a trade-off with focus shift at f/2.8, but that is covered by the increased depth-of-field, so it would play no important role.

Then why not adjust the lens like this from beginning? To me it sounds better having a focus shift stopped down if it is covered by DOF, than having a focus shift wide open which is not covered by DOF. If I buy a fast lens, I would expect it to be sort of optimized for wide open performance.

Also, how does focus distance play into this? It should be more of a problem close-up?

/Håkan

exactly!!


joe

 

[tbarker13]

I am leaning toward having the change made, though I will probably wait unitl my 50 lux arrives in a few weeks.
I'll try to get some test shots before and after for comparison.