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Old 01-03-2019   #41
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You're welcome. We did have a good Leica tech in Perth, Western Australia but he retired recently. I did the rangefinder adjust myself as I didn't have any of my lenses with me when I went to Perth to have the shutter speeds on the M6 adjusted.
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Old 01-03-2019   #42
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May help but there is a longish post on 35mmc about the Zeiss C Sonnar. Hamish McGill asked Zeiss about the settings from factory for the lens for focus shift - in the article but the summary

"The out-of-factory adjustment of the 50mm C Sonnar when combined with a perfectly adjusted camera rangefinder will show about 1.5cm front focus at f/1.5 and 1m focusing distance, perfect focus at f/2 and 1m focusing distance, and about 2-3cm back focus at f/2.8 and 1m focusing distance."

That may or may not help!
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Old 01-04-2019   #43
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PFD, I am in Sydney too. You're welcome to try your lens on my M9 and digi CL if you like. It will give you an idea where the misfocusing lies.
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Old 01-04-2019   #44
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PunkFunkDunk, congratulations on your new purchase. I've read what the other people posted on this thread and I must say that some replies were more or less inaccurate.

I have had my C-Sonnar adjusted by Zeiss in Obekochen for what the people at Zeiss consider "the best compromise". This means that the photographer must accept a slight front focus when shooting wide open and slight back focus when closing down. How much front focus and how much back focus at minimum focus distance? About 1.5 cm when shooting wide open at the minimum focus distance (90 cm). As you close down to F2.0, the front focus roughly halves and by F2.8 the lens starts to back focus a little. In other words, the "best compromise" is a lens adjusted for perfect focus at F2.2 or F2.5.

What can you do? Put your camera on a tripod and shoot wide open a chart at minimum focus distance. Focus as carefully as you can and shoot. Without refocusing, start closing down the lens and take a photo at each individual step. Do it until you reach F4.0. Analyze the frames. The focus should move backwards with each individual shot. When the target is in perfect focus, that is your workable aperture. In my case, as I mentioned, is F2.2 or F2.5 (can't really remember my result). You will use this aperture as the "safe aperture". If you close down, you'll have to slightly compensate to bring the focus slightly closer and vice-versa.

Most of the spherical lenses with no floating elements do focus shift. Even the Planar 50/2 does it it little. The Biogon 35/2 a little more. But the C-Sonnar is the worst offender. However, it can be tamed.

If you don't like "the best compromise", you can have your lens adjusted for shooting wide open, but you can say goodbye from shooting closed down, as the manual compensation will have to be a lot larger - and therefore impractical.

Alex
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Old 01-04-2019   #45
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Quote:
Originally Posted by PunkFunkDunk View Post
Forgot to add that my incentive to figure out the C Sonnar use is that in my M system hiatus last year I shot mostly a F2AS with Zeiss 50/1.4 ZF.2 but found the Planar renderings vanilla. Nothing wrong, but nothing magical, unless the light made it so anyway. Which is true of all lenses of course but the C Sonnar makes even pedestrian assemblages or still life objects sing. And the portraits of course.

As I say this I just recalled my short stint with the CV 50/3.5 Heliar that I fooled around with back when I had my M2 three years ago. Amazing optics but horrible ergonomics for casual shooting. Still regret selling it however. I do not wish to repeat that seller remorse with the C Sonnar through my own temperamental impatience. To be continued. Somehow I always bleed money with the bloody M system.
Now you are talking. First thing i would find a tech around you.. And calibrate everything.
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Old 01-04-2019   #46
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Quote:
Originally Posted by alexandru_voicu View Post
PunkFunkDunk, congratulations on your new purchase. I've read what the other people posted on this thread and I must say that some replies were more or less inaccurate.

I have had my C-Sonnar adjusted by Zeiss in Obekochen for what the people at Zeiss consider "the best compromise". This means that the photographer must accept a slight front focus when shooting wide open and slight back focus when closing down. How much front focus and how much back focus at minimum focus distance? About 1.5 cm when shooting wide open at the minimum focus distance (90 cm). As you close down to F2.0, the front focus roughly halves and by F2.8 the lens starts to back focus a little. In other words, the "best compromise" is a lens adjusted for perfect focus at F2.2 or F2.5.

Alex
I agree with Alex. His figures here are almost exactly what I found in my tests, https://www.photo.net/discuss/thread...or-1-5.461113/ with my lens optimised for around f2.4. M Fogiel found that a truly 1.5 optimised lens is almost unusable at f2.8 and f4 because of the back focus. He has another optimised for 2.8.

Focus shift is unavoidable and you just have to learn to live with it. Close in it is better not to use f1.5 if you can help it, if you need critical focus. Or bracket the focus. Or just take several shots. Standing with a camera to your eye you may have at least 1cm body sway anyway.
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Old 01-04-2019   #47
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Quote:
Originally Posted by PunkFunkDunk View Post
Forgot to add that my incentive to figure out the C Sonnar use is that in my M system hiatus last year I shot mostly a F2AS with Zeiss 50/1.4 ZF.2 but found the Planar renderings vanilla. Nothing wrong, but nothing magical, unless the light made it so anyway. Which is true of all lenses of course but the C Sonnar makes even pedestrian assemblages or still life objects sing. And the portraits of course.

As I say this I just recalled my short stint with the CV 50/3.5 Heliar that I fooled around with back when I had my M2 three years ago. Amazing optics but horrible ergonomics for casual shooting. Still regret selling it however. I do not wish to repeat that seller remorse with the C Sonnar through my own temperamental impatience. To be continued. Somehow I always bleed money with the bloody M system.
Agree. No need for seller's remorse here - you got a special lens for a good price that you can resell if it doesn't work for you. You stand to lose nothing by calibrating everything and working with it for a while. That way if you eventually sell it you'll be selling a lens you've analyzed thoroughly instead of just punting it prematurely.
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This!!!
Old 01-04-2019   #48
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This!!!

Quote:
Originally Posted by Dante_Stella View Post
Tip: slavishly following the RF is not helpful on any Sonnar. To hit focus below f/2.8, you will turn the focusing ring to the left by a hair (toward infinity). It will be the smallest perceptible motion you can make with the focusing ring (as in you just feel it move).

Your only other option is to recollimate the lens for f/1.5, which will royally screw up your focus at f/2-2.8-4 (and possibly 5.6) unless you are committed to hiking the focus in the other direction. I think it's better to work with it set at 2.8; this is the same way every single fast lens is anyway (the 75/1.4 is exactly the same thing) - they all front-focus at wide apertures.

And in terms of affect, front-focus is almost always preferable to back focus.

I have used pretty much every version of the Sonnar that you can jam on a Leica, and they all behave pretty much identically. Sonnars are also far easier to learn on a digital body, since you can instantly see what your focusing technique is doing.

D
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Old 01-04-2019   #49
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It is still possible to test this kit without additional lens,
With ground glass or its alternative.
If it is rangefinder or lens shift then distance mark on the lens and matching distance between target and ground glass should give sharp image on the ground glass,
If not, then something is wrong with the lens.
Is here any wobble, loose parts on the back?

Here is Nokton 50 1.5 asph. No focus shift issues and very pleasing rendering.
I had Planar and many J-8. I didn't find significant difference in rendering between them.
J-3 is diffrent. Planar should be sharp out of the box. Most J-8 has to be shimmied.
Most easy to shim are black ones. They also gives more contrast.
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Old 01-04-2019   #50
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I have been through all of this as well, twice. I did a lot of testing and in my case I did not find any defective equipment, but I did learn the behaviour of my lens on different cameras. The C-Sonnar is a really fantastic lens, one of my favourites, but I might not feel that way if I did not know that mine is optimal at f1.5 on film, and f2.2 on digital, and in time learn how to compensate for that. What an amazing lens though!

Before you spend big bucks, spend another roll of film on a common sense but controlled test. Here is what worked for me:
1.) Camera on a tripod
2.) Place camera at close focus to a bookshelf at an angle
3.) Focus - and remember (or better write down) the book spine you focus on
4.) Run through the apertures at equivalent exposures
5.) Place the camera/tripod at 2m (but consistent angel) from the bookshelf - repeat
6.) Repeat the above with another lens that you know doesn't have issue
7.) Develop film, print/scan/whatever
8.) Analyse the results

Consider the time and few dollars you spend to do this test as the price of confidence in whatever you do next. If you want to be even more scientific, feel free to measure the distances and angles, have fun with pythagorus, etc., but in my case I as soon as I saw the the prints / scans / jpgs I had a very good feeling for what I was dealing with.

Cheers,
Rob
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Old 01-04-2019   #51
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I have one that’s optimized for f1.5, which is how I use it most of the time. I eeven go to the extent of using an ND filter so I can still shoot at f1.5 if it’s too bright. So the focus shift is a non-issue for me. For other uses, e.g., at f2.8 to f5.6, I switch to my Planar.
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Old 01-04-2019   #52
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I just couldn't live with the focus shift and sold the C-Sonnar. The size is great and the look at is really nice for people shots, but I'm sticking with the Planar.

And maybe getting a vintage Sonnar type lens for those urges...
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Old 01-04-2019   #53
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Quote:
Originally Posted by robbeiflex View Post
I have been through all of this as well, twice. I did a lot of testing and in my case I did not find any defective equipment, but I did learn the behaviour of my lens on different cameras. The C-Sonnar is a really fantastic lens, one of my favourites, but I might not feel that way if I did not know that mine is optimal at f1.5 on film, and f2.2 on digital, and in time learn how to compensate for that. What an amazing lens though!

Before you spend big bucks, spend another roll of film on a common sense but controlled test. Here is what worked for me:
1.) Camera on a tripod
2.) Place camera at close focus to a bookshelf at an angle
3.) Focus - and remember (or better write down) the book spine you focus on
4.) Run through the apertures at equivalent exposures
5.) Place the camera/tripod at 2m (but consistent angel) from the bookshelf - repeat
6.) Repeat the above with another lens that you know doesn't have issue
7.) Develop film, print/scan/whatever
8.) Analyse the results

Consider the time and few dollars you spend to do this test as the price of confidence in whatever you do next. If you want to be even more scientific, feel free to measure the distances and angles, have fun with pythagorus, etc., but in my case I as soon as I saw the the prints / scans / jpgs I had a very good feeling for what I was dealing with.

Cheers,
Rob
I agree with this as a good cheap next test. The tripod is essential because of body sway. Hand held you can never work out focus shift reliably. The child on the beach shot of yours almost couldn’t be due to the lens unless every shot you take is as bad. I will say that focussing a Leica in portrait mode is very difficult and prone to gross errors.
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift
Old 01-06-2019   #54
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift

Quote:
Originally Posted by pyeh View Post
PFD, I am in Sydney too. You're welcome to try your lens on my M9 and digi CL if you like. It will give you an idea where the misfocusing lies.
This is a very kind offer! My plan is to carry out some testing of the lens across apertures with a tripod to see if I can deduce where my copy is best calibrated. As I do not own any digital bodies on which to adapt it, this is somewhat tedious to do on film. If I am unable to come to any consistent conclusion then I would absolutely love to take you up on this offer! Of course, would happily shout you a lunch at a cafe for the privilege! Great generosity here on RFF ...
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Old 01-06-2019   #55
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Thank you to everyone who responded with useful advice. This portrait of my son is the best frame on three rolls of Ektar that I first shot with the C Sonnar. Yes, a touch soft at the point of intended focus, but still magical character and 3D rendering of a kind I have never experienced with lenses in 35mm systems (I can only achieve this look with my Pentax 67 105/2.4). So I will persevere. Got in touch with Youxin to book my CLA to ensure my M6 RF alignment is OK and as previously mentioned my patch flares badly so will invest in the MP finder upgrade while I am at it. More outlay of $$$ but hopefully it will pay for itself in satisfaction over the years if I can tame the C Sonnar.
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift
Old 01-06-2019   #56
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift

Last night I was scanning some frames shot with my Zeiss 50/1.4 ZF.2 on a F2AS (both sold to fund the C Sonnar) and the difference in rendering is palpable despite the Nikon mount Zeiss being no slouch.
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Old 01-07-2019   #57
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PFD, definitely a good idea to get your M6 checked over. PM me anytime if you want to use my digicams for testing. Much more convenient than film. You can also compare your ZM 50/1.5 with mine. Mine behaves exactly as described by Alexandra Voicu above.
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Old 01-07-2019   #58
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Quote:
Originally Posted by PunkFunkDunk View Post


Thank you to everyone who responded with useful advice. This portrait of my son is the best frame on three rolls of Ektar that I first shot with the C Sonnar. Yes, a touch soft at the point of intended focus, but still magical character and 3D rendering of a kind I have never experienced with lenses in 35mm systems (I can only achieve this look with my Pentax 67 105/2.4). So I will persevere. Got in touch with Youxin to book my CLA to ensure my M6 RF alignment is OK and as previously mentioned my patch flares badly so will invest in the MP finder upgrade while I am at it. More outlay of $$$ but hopefully it will pay for itself in satisfaction over the years if I can tame the C Sonnar.

No pain no gain. You like the lens. Now tame the beast.
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Old 01-07-2019   #59
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Q: My lens doesn't focus properly. What should I do?
A. Get a lens that focuses properly. All the character, magical rendering, pop, and wow factor won't make up for an out of focus image.
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Old 01-07-2019   #60
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Originally Posted by ptpdprinter View Post
Q: My lens doesn't focus properly. What should I do?
A. Get a lens that focuses properly. All the character, magical rendering, pop, and wow factor won't make up for an out of focus image.
There is another option.
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift
Old 01-15-2019   #61
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift

Update: So I got some lab scans back of my focus shift test with the C Sonnar. I will spare you the excitement of the pictures of a measuring tape, but I am just keen to know if my deduction chimes with consensus on how this lens may operate. Any helpful feedback much appreciated.

OK, so I am pretty confident I can say I have a 1.5 optimised version. Point of focus at minimum focal distance was accurate at f/1.5; front shifted by 3 centimetres at f/2; front shifted by 2 centimetres at f/2.8; horrendously back shifted by 4-5 centimetres at f/4 and even f/5.6; then f/8 through f/16 all fine (though I detect slight continuation of back shift at MFD). Go figure. To be completely honest, all of this could just as easily be user error despite my care using the tripod. And it is difficult to deduce the best point of focus for some of the apertures based on the lab scans as I am no veteran pixel peeper.

However, in addition to sacrificing a roll on this test of patience and utter boredom (I was embarrassed to pick up the scans at the lab!) I put a roll of Ultramax through the M6 with the C Sonnar and just shot at most apertures. No notepad. No record. No worries. Maybe 6 frames unacceptably out of focus (only at MFD) from a roll of 36. Everything else magic such as the below. Ah, yes, this is why I love the lens.

In other words, I am not cut out to bother with slide rules and certainties. Life is too short. My attitude? Just shoot and accept that each roll of film will cost a 20 per cent dud tax for 80 per cent brilliance, at least as far as rendering goes before the more vital question of content. That seems better odds than life itself can offer. Yes, I am definitely keeping the lens even if I am none the wiser as to how it does what it does and how it does not. Simply put, in my limited experience and within my limited budget (never gonna own a Summilux) the C Sonnar is the only lens in 35mm format I have seen that even comes close to passing off renderings akin to the awesome Pentax 67 105/2.4.

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Old 01-15-2019   #62
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Quote:
Originally Posted by PunkFunkDunk View Post

OK, so I am pretty confident I can say I have a 1.5 optimised version. Point of focus at minimum focal distance was accurate at f/1.5; front shifted by 3 centimetres at f/2; front shifted by 2 centimetres at f/2.8; horrendously back shifted by 4-5 centimetres at f/4 and even f/5.6; then f/8 through f/16 all fine (though I detect slight continuation of back shift at MFD). Go figure.
Weird results. Did you have the camera on a tripod? I'm guessing you didn't?

The reason I say "weird" is because the point of focus can only shift backward away from the camera as you stop the lens down, regardless of what aperture the lens is optimized for. Assuming you were hand holding the camera, you lent slightly backward when you shot at f2 and f2.8
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Old 01-15-2019   #63
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If you lens is optimized for F1.5 (which I doubt), the point of focus will inexorably move backwards when you stop down. That until F11 or so, when it will (or so they say, but never tested it) move to the front again.


In other words, the point of focus at F2.0 will be behind the point of focus at F1.5. And so on.


As I - and others - already said, you have to test it on a tripod.


PS In the photo at the table, I believe the focus is in front of the target. The real point of focus is somewhere on the content of the plate.
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Old 01-15-2019   #64
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These focus shift tests aren't easy. See my set up:

https://www.photo.net/discuss/thread...or-1-5.461113/

Here also is Marek Fogiel's testing of a 1.5 and a 2.8 optimised lens:

http://www.rangefinderforum.com/foru...l+zeiss+sonnar.
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift
Old 01-15-2019   #65
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Got a great deal on a Zeiss C Sonnar ... struggling with focus shift

Yes weird. I did in fact use a tripod. Was as careful as I could be in keeping it stable. I think the error is in my actual judgement of what is sharp and what is not! I think from herein if I dedicate any more time to it I will just have to test it on a mirrorless digital body somehow with focus peaking. Just too large a margin for error in film when slightly out of focus shots look great anyway. For instance I can see that in the image I just posted the TV dinner is more sharp than the face, but guess what? It makes for a better, more enigmatic portrait. My view anyway.
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Old 01-15-2019   #66
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I agree that testing on a mirrorless like my Sony A7S will show the true behaviour of the lens. When I test my Sonnar C on the Sony at 1 meter, focus consistently moves back as it stops down from f1.5 to f5.6, for a total distance of something like 8cm, so roughly 2 cm per aperture stop.
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Old 01-15-2019   #67
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Quote:
Originally Posted by mcfingon View Post
I agree that testing on a mirrorless like my Sony A7S will show the true behaviour of the lens. When I test my Sonnar C on the Sony at 1 meter, focus consistently moves back as it stops down from f1.5 to f5.6, for a total distance of something like 8cm, so roughly 2 cm per aperture stop.
John Mc


Very useful. Thanks. I have a mate with a Sony will will likely fork out $$ myself for the adapter to see ...
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Old 01-15-2019   #68
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Your focus shift pattern sounds weird, it should shift back not forward, as others have said. Definitely check your M6 with a known good lens. Maybe you have a 50 f2 that you know works, or maybe a friend who will let you try their 50 summilux or VM Nokton.

Digital body for testing is a great idea. It is less forgiving than film, and may have a slightly different result, but will teach you a lot. You still have to learn your lens on film to get it right though. Focus shift diminishes with distance, so you may be better off bracketing focus at short distances until you get it, then you waste frames but lower the risk of missing

If you do get work done on the M6, do get the MP upgrade/flare fix. I did this on mine and it is worth it!

Cheers,
Rob


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Old 01-15-2019   #69
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I like post #61. You can either spend your life stressing about it or you can move ahead and enjoy your photography. There is SO much more to life...and photography...then pin sharp photos.

Enjoy your lens and your family.

Besides, you will find that with time you do get better at using the lens.
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Old 01-15-2019   #70
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A new YT video on that lens showed up 2 days ago and at around 8 min. into the video the author discusses how to solve the focus shift problem with the lean in method.

https://www.youtube.com/watch?v=j66_NDHdOSY
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Old 01-15-2019   #71
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Originally Posted by alexandru_voicu View Post
PunkFunkDunk, congratulations on your new purchase. I've read what the other people posted on this thread and I must say that some replies were more or less inaccurate.

I have had my C-Sonnar adjusted by Zeiss in Obekochen for what the people at Zeiss consider "the best compromise". This means that the photographer must accept a slight front focus when shooting wide open and slight back focus when closing down. How much front focus and how much back focus at minimum focus distance? About 1.5 cm when shooting wide open at the minimum focus distance (90 cm). As you close down to F2.0, the front focus roughly halves and by F2.8 the lens starts to back focus a little. In other words, the "best compromise" is a lens adjusted for perfect focus at F2.2 or F2.5.

What can you do? Put your camera on a tripod and shoot wide open a chart at minimum focus distance. Focus as carefully as you can and shoot. Without refocusing, start closing down the lens and take a photo at each individual step. Do it until you reach F4.0. Analyze the frames. The focus should move backwards with each individual shot. When the target is in perfect focus, that is your workable aperture. In my case, as I mentioned, is F2.2 or F2.5 (can't really remember my result). You will use this aperture as the "safe aperture". If you close down, you'll have to slightly compensate to bring the focus slightly closer and vice-versa.

Most of the spherical lenses with no floating elements do focus shift. Even the Planar 50/2 does it it little. The Biogon 35/2 a little more. But the C-Sonnar is the worst offender. However, it can be tamed.

If you don't like "the best compromise", you can have your lens adjusted for shooting wide open, but you can say goodbye from shooting closed down, as the manual compensation will have to be a lot larger - and therefore impractical.

Alex
This is a most accurate response. From what I understand from Zeiss and have witnessed in my not all that long ago purchase of a brand new Zeiss C-Sonnar 50mm f1.5 (and testing three new ones out of the box), the recent lenses are factory adjusted to approx. f2-f2.2 and behave as described by Alex. In effect, there is relatively minimal focus shift "observed" at all apertures with these recent lenses. An acquaintance on another forum observed precisely the same with his recently purchased new lens (within the last 18 months or a bit more).

Ones previously optimized for f1.5 or 2.8 can be readjusted for optimal focus at f2-f2.2, emulating the most recent production runs of this lens. Of course a store having old-new stock, one would have no way of knowing initially out of the box, what that particular lens was optimized for by Zeiss at the time of its production.

Dave (D&A)
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Old 01-15-2019   #72
PunkFunkDunk
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Quote:
Originally Posted by D&A View Post
This is a most accurate response. From what I understand from Zeiss and have witnessed in my not all that long ago purchase of a brand new Zeiss C-Sonnar 50mm f1.5 (and testing three new ones out of the box), the recent lenses are factory adjusted to approx. f2-f2.2 and behave as described by Alex. In effect, there is relatively minimal focus shift "observed" at all apertures with these recent lenses. An acquaintance on another forum observed precisely the same with his recently purchased new lens (within the last 18 months or a bit more).

Ones previously optimized for f1.5 or 2.8 can be readjusted for optimal focus at f2-f2.2, emulating the most recent production runs of this lens. Of course a store have old-new stock, one would have no way of knowing initially out of the box, what that particular lens was optimized for by Zeiss at the time of its production.

Dave (D&A)


Very useful. Thank you. I bought mine used and while it looks mint I have no idea when it was manufactured. As I am sending my M6 to Youxin soon to get the MP finder upgrade (my RF patch flares badly), I might ask if he can recalibrate the lens too.
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Old 01-15-2019   #73
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As I mentioned before, my copy behaves like alexandru-voicu's exactly, when I tested it. I bought mine new in January 2012.
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