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To keep C Sonnar or not?

edwardkaraa

New member
Having used the C Sonnar for a couple of weeks now, I'm still very undecided about it. My copy is optimized for wide open shooting, which means it back focuses strongly when stopped down. When shooting at infinity, I need to pull back the focusing ring by about 3 mm to get the best sharpness at f/8. The Planar remains obviously sharper for this kind of shooting and has no focus shift. So if I keep the Sonnar, it's only to shoot it wide open in low light, where it really shines. Here is a little comparison handheld at 0.90m:


C-Sonnar 1.5 by edward karaa, on Flickr


C-Sonnar 2.0 by edward karaa, on Flickr


Planar 2.0 by edward karaa, on Flickr
 

StephenPatterson

New member
This lens caused me nothing but frustration when I owned it.

Of course with the new M and live view you would be able to work around the focus shift issues, but that is a slow way to shoot. I am using the live view and EVF only for very low light of ultra shallow DOF shots, but the rangefinder is so much better and faster I always prefer it.

Ditch it and get a 50 Summilux ASPH. Problem solved. Check, please!
 
V

Vivek

Guest
Edward, If you are going to use it stopped down more often than wide open, then the Planar is better. C-Sonnar's aperture dependent focus shifts are well documented.

The description that a lens sample is "optimized for wide open shooting" is a new twist to an old problem that this lens suffers from. :D

If by any chance you are going to buy an MM, keep it. If you are going to get an M, also keep it- both for very different reasons. With the former the focus shift will still be in play but with the latter and using liveview it should not be a problem.
 

edwardkaraa

New member
Thank you Stephen for your comment. I totally agree about the frustration. It's almost impossible to get sharp results stopped down. But I really love the rendering WO. The cheaper option is to keep both lenses, one for bokeh, and the other for high contrast biting sharpness :)

Vivek, thank you as well. Wide open optimization refers to the RF mechanism. It gives you the best sharpness at 1.5, but the problem is that the focus shift becomes too strong to be covered by DOF when stopped down.
 

D&A

Well-known member
Hi Edward,

Although a bit different and somewhat less that the C-Sonnar, the Leica 35mm Lux asph prior to the current FLE model also exhibits a well known focus shift and it also frustrated me at times. One way that partially circumvented it's impact was to have the lens achieve (optimize as some would say) precise best focus at approx f2.0 or f2.4. This way when at close range and shooting wide open there would just be a very small amount of front focus (primarily at close range with it's smaller depth of field), then at approx f2-f2.4, focus would be dead on, and finally at approx f4-f4.5, just a small amount of back focus as the larger depth of field at that aperture would cover most of the slight mis-focus.

Although I've never owned my own copy of the C-Sonnar, I often see that some have a copy designed for best focus wide open which would then have quite noticeable back focus at f2 thru approx f4.5 or beyond....too much for the growing depth of field to simply cover most of it. Then there are the well known copies of this lens that came from Zeiss adjusted for best focus at f2.8. These have quite noticeable front focus at f1.4 and not at just close range. There is no reason that DAG or some others, maybe even Zeiss couldn't have their lens adjusted for best focus at approx f2.2. This way it splits the difference as described.

The one difference though to note is the following. Where I personally have had this adjustment done with two copies of the 35mm Lux asph (pre FLE) and it worked wonderfully as I just described, my feeling is the C-Sonnar has a somewhat bigger focus shift than most copies of the C-Sonnar, so even with the lens adjusted for best focus at a "compromise aperture" of approx f2.2 or thereabouts, some focus shift (although much less) will be seen in either direction at f1.5 and f4.5...but at least I personally feel the lens would be more usable at at given aperture when adjusted this way. My 35mm Lux asph (pre FLE) lenses certainly were and frustration in using them was significantly reduced. Only when I examined the files at 100% would it really be noticeable or a factor for me.

The idea of using a lens primarily only at say wide open and then again at f8, and nothing in-between doesn't appeal to me personally.

Dave (D&A)
 

edwardkaraa

New member
Thank you Dave. Exactly my thinking. I was kind of hoping the lens would be optimized for f/2.8 when I ordered it, but it seems after so many owners were very vocal about wide open optimization, Zeiss decided to optimize all new batches for f/1.5 instead of the original f/2.8.

I can still send it back to Zeiss for re-calibration, but it's going to cost me shipping to Zeiss, and import tax/VAT when I receive it back, so I would rather sell it and be happy with the Planar.
 

Godfrey

Well-known member
I'd buy one of the C Sonnar lenses to use with the Ricoh GXR and Leica M (240), as the focusing frustration disappears with Live View focusing. 50mm is a bit too long for me with the GXR on APS-C format, though ... I seem to want 40mm most of the time, then jump to 90mm with this camera.

So maybe the solution is to wait for when I buy a new M and include this lens with that purchase...

G
 

D&A

Well-known member
Thank you Dave. Exactly my thinking. I was kind of hoping the lens would be optimized for f/2.8 when I ordered it, but it seems after so many owners were very vocal about wide open optimization, Zeiss decided to optimize all new batches for f/1.5 instead of the original f/2.8.

I can still send it back to Zeiss for re-calibration, but it's going to cost me shipping to Zeiss, and import tax/VAT when I receive it back, so I would rather sell it and be happy with the Planar.
Hi Edward,

As much as calibrating to f1.5 is a headache with regards to focus shift, so is calibrating it to f2.8! My suggestion is have someone like DAG calibrate it for approx f2 or if possible f2.2. In other words, split the difference between f1.5 and f2.8! Hope that makes more sense based on my more lengthier explanation in my post above.

Dave (D&A)
 

edwardkaraa

New member
Thank you Dave. Yes, it definitely makes sense, so if I decide to keep the Sonnar, I should probably have it adjusted as you recommend.
 

Double Negative

Not Available
Easy. Don't stop it down! ;)

I loooove my C Sonnar. But mine's optimized as Zeiss and god intended - at f/2.8. So yeah, it requires a little mental work before tripping the shutter... With a little use, you get the hang of it.
 

Hosermage

Active member
I've own a ZM50 C-Sonnar (optimized at f/2.8) as my only lens for a long time. To me, worrying about focus shift only on the wide end is much better than worrying about focus shift in the mid range, even though I shot a lot at f/1.5. You can simply learn to tweak the focus ring by a bit to adjust for the focus shift.

In the end, I traded up for a 50'Lux ASPH for many other reasons: slide out hood (save space), focus tab (ergonomics), 6-bit coding for EXIF (laziness), and knowing exactly who to blame for OOF shots (me) was a plus. I was never, however, displeased with the IQ from the sonnar.
 

edwardkaraa

New member
Thank you DN and David. Yes, it seems that having the lens optimized for WO makes it difficult to use at other apertures. But on the other hand, I can't think of any other reason to get the Sonnar except to shoot it WO, as this is where it really draws nice. I think the Planar is much better for "non artistic" photos.
 

ced

Member
Edward I think your shot at 1.5 is better than the other 2 from every point, the background is lovely and the sharpness is spot on and you lose that great creamy BG with the f2 Planar. Shoot some portraits and not still life and see what makes it so magical at 1.5.
 

douglasf13

New member
Hi, Edward. I used the C-Sonnar on NEX, and I considered it when purchasing the M9, but I decided against it, because of both the focus shift and the across the field sharpness even when stopped down. I'm a one lens at a time kind of guy, so I would rarely carry two 50s with me, and I wouldn't want to give up some of the f4-5.6 performance across the field. Interestingly, I've read a few threads where those shooting the C-Sonnar for portraits actually think that the f2-f2.8 range is where the lens really shines. If I did buy one again, I'd likely get it optimized for f2.8 and learn the offset for wider apertures...or lean a little forward.

To be honest, Edward, simply judging by your photographs that I've seen over the last several years, I would think that the Planar is the right 50 for you, but I certainly can't tell you what is right for your own art. Heck, if it were up to me, I'd probably just tell you to use that ZM 25 and throw everything else away, because I think it really works with your eye. Really great work with that lens. :thumbs: I don't think I could shoot a 25mm to save my life! :banghead:

The wide aperture, small size, flare suppression and interesting bokeh are all certainly alluring with the C-Sonnar. Tough call.
 

D&A

Well-known member
Thank you Dave. Yes, it definitely makes sense, so if I decide to keep the Sonnar, I should probably have it adjusted as you recommend.
The one thing to consider is by having it adjusted for most accurate focus at approx f2, will still result in the lens having some front focusing at f1.5 and some back focusing at F4.5, but far less at one or the other if you had instead had it adjusted for either F1.5 or f2.8. That's because the focus shift of the C-Sonnar is greater in magnitude that the focus shift found in Leic"s 35mm Lux asph (preFLE). With the Leica, having it adjusted for f2 results in just a little focus shift at f1.4 and f4.5.

I do believe that if you do have you lens adjusted for approx f2, since you will still have a small amount of front focusing at f1.5...you won't loose the beautiful OOF rendering wide open for the most part, but will also have a lens that's still worth shooting at other apertures. I'm of the school of thought that just because a certain lens renders both exceptional and unique at a given aperture, it still will be a lovely lens when shot at other apertures.

Dave (D&A)
 

Kokoshawnuff

New member
If I shot 50mm more I would have kept the C Sonnar to go with my lux ASPH. My sonnar was optimized for f/2.8 and I never had an issue with focus shift on film, and on digital one would just need to focus and lean forward a bit when wide open. If you love the 50mm focal length then I see nothing wrong in having a sharp and consistent performer (ie your planar), and a lens that has some character and a bit of softness (ie your sonnar).
 

teeraash

New member
Hi Edward:
My copy is exactly the same as Kokoshawnuff, it is optimized at f2.8. At far and medium distances, I don't have to adjust anything. They are all tack sharp. Here are images I took this morning during my heavy breakfast from 1.5, 2.0, 2.8, 4.0, 5.6 and 8.0. The f1.5 is sharp enough already except to the extreme edges but it becomes really good at f2.8. So even at f2.8 it is already ok for landscape except that one may not have enough DoF. You can look at full size images at my Flickr pages.

F1.5
[/url]
L1002894.jpg by teera_ash, on Flickr[/IMG]

F2.0

L1002895.jpg by teera_ash, on Flickr

F2.8

L1002896.jpg by teera_ash, on Flickr

F4.0
[/url]
L1002897.jpg by teera_ash, on Flickr[/IMG]

F5.6
[/url]
L1002898.jpg by teera_ash, on Flickr[/IMG]

F8.0

L1002899.jpg by teera_ash, on Flickr

All images were taken a fraction of a second to each others and with the same minor adjustments in LR. Should be noted that the F4.0 image is not as sharp as it should be and this may have to do with the operator not the lens. :eek:
 

teeraash

New member
For a wide open f1.5 images at really close distance, say 1m to 2m, all I have to do is leaning forward about and inch to get perfect sharp image at intend focusing point such as the near eye of the model. With some practices, it has become my second nature. Here, are some at wide open aperture.

[/url]
L1001133.jpg by teera_ash, on Flickr[/IMG]

[/url]
L1001131.jpg by teera_ash, on Flickr[/IMG]
 
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