Go Back   Rangefinderforum.com > Cameras / Gear / Photography > Leicas and other Leica Mount Cameras > Konica RF / Zeiss Ikon ZM Leica Mount Rangefinders

Konica RF / Zeiss Ikon ZM Leica Mount Rangefinders Konica and Zeiss versions of the AE electronic film rangefinder camera

Reply
 
Thread Tools Search this Thread Display Modes

Comparative focus test of 2 versions of C Sonnars
Old 12-22-2007   #1
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
Comparative focus test of 2 versions of C Sonnars

As promised, I am back to show you my findings about the 2 different versions of C Sonnar 50/1.5 - the first batch "optimized for focus at f2.8" and the second batch, "optimized or corrected (as in this case) for focus at f 1.5".

Since this is a user test and far from being scientific in precision, I'd like to say right away, that these results can be prone to some absolute error - what I was trying to understand foremost was the RELATIVE behaviour of these lenses across apertures.

My test was done on a tripod, with my M7 0.85x placed at slightly beyond 1 meter (measured with a ruler) from the "focus here" line, and at a fairly accurate angle of 45°. I wear glasses, and this is how I normally focus my rf cameras, so I kept them on for this test as well.

In order to have a reference point, I took one shot with the Planar 50/2 at f2.0, in order to see if my eye was calibrated decently, and I think the result is acceptable as a "neutral" starting point.

The shots are scanned without any post processing, with the exception of a contrast boost in PS - equal for all the scans, in order to improve the reading of the numbers.

Let's first see the results from the Planar shot, and the f1.5 and f2.0 shots. In the second post I will add the rest and discuss the results.
Attached Images
File Type: jpg [email protected],0.jpg (105.1 KB, 1787 views)
File Type: jpg [email protected],5.jpg (116.6 KB, 2186 views)
File Type: jpg [email protected],0.jpg (111.0 KB, 1685 views)

Last edited by mfogiel : 12-22-2007 at 14:20.
  Reply With Quote

Old 12-22-2007   #2
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
Here I include the shots at f2.8, f 4.0 and f5,6 - I did not include the test at f8,0, because I detected no further focus shift, and the dof took pretty much care of all focusing issues.
Attached Images
File Type: jpg [email protected],8.jpg (110.7 KB, 1373 views)
File Type: jpg [email protected],0.jpg (111.8 KB, 1095 views)
File Type: jpg [email protected],6.jpg (116.2 KB, 1033 views)

Last edited by mfogiel : 12-22-2007 at 14:21.
  Reply With Quote

Old 12-22-2007   #3
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
I've made little brackets 4cm wide, to mark the best focus zone, and put an arrow where to my eyes, the image looked sharpest.
First of all, the reference Planar shot is really quite impressive, because it really is spot on the target, i.e. the black line with the "focus here" text.

The f1.5 shots show you right away what's happening - the "new" C Sonnar looks like it's missing the precise point by 1cm, but the dof covers the best focus quite well, while the "old" version is plainly off, front focusing by about 5 cm, which is not so easy to manage in real life, making this version little usable wide open.

The f2.0 shots display a similar story, and here indeed one can see the phenomenon described by Roger Hicks and Dr Nasse - in the "new" version, the usable dof sits right behind the point of best focus. Since f2.0 is probably the most interesting aperture for low dof portraits, because it gains quite a bit of contrast with respect to wide open, yet the bokeh remains exceptional, obviously this version should perform well for the "dreamy and creamy" assignements. The "old" version is a bit like a fish out of the water here.

At f2.8 we see a capsized situation: the "new" version is disappearing behind the horizon, while the "old" starts pulling out the bite, and is entering the best overall performance zone. I suspect this lens is at it's best around f3.5, and this is where Zeiss has actually calibrated it in the first place.

At f4.0 the "new" version has become almost unuseable, while the "old" version focuses like the "new" one wide open, and, believe me, at this aperture delivers the goods in large amounts...

Finally, at f5,6 the relative best focus does not move by a detectable amount, but the dof increases, making the "new" version just useable - by f8,0 the focus stays the same and both lenses cover easily the "focus here" sign.

It is difficult to draw a definitive conclusion just on the basis of some ruler shots, and in fact I'd like to make some real portraits with both lenses, to see how it works out in practice.
However, if you are attracted to the C Sonnar for its absolute bokeh wide open, or for using it exclusively in low light and between f1.5 and f2.0, then the "new" version is for you, but you better keep another 50mm lens handy for more general shooting. On the other hand, if you like the soft but contrasty drawing with good detail, which this lens delivers between f2.8 and f4.0, plus you do not disdain great sharpnesss beyond f5.6, then the "old" version should be for you, and you might want to keep one of the older f1.4 or f1.5 lenses for the wide open soft images.

Last edited by mfogiel : 12-22-2007 at 13:43.
  Reply With Quote

Old 12-22-2007   #4
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
Just to leave you with something from real life, the attached photo has been made with the "new" version at f2.0 from a distance of about 1.3m, and I focused on the eyes of the girl to the left.
Attached Images
File Type: jpg double portrait.jpg (117.0 KB, 1932 views)
  Reply With Quote

Old 12-22-2007   #5
thomasw_
Registered User
 
thomasw_'s Avatar
 
thomasw_ is offline
Join Date: Nov 2006
Location: Fort Langley, BC
Age: 51
Posts: 1,626
I enjoyed examining your findings mfogiel. thanks for posting this, as it makes it clear that the version optimised for f1,5 would be the one for me.
__________________
f l i c k r
  Reply With Quote

Old 12-22-2007   #6
willie_901
Registered User
 
willie_901's Avatar
 
willie_901 is offline
Join Date: Dec 2005
Posts: 4,502
This is a very useful test. Thanks for taking the time to share the results.

However, I must say that I never use my rangerfinder camera at a subject distance of 1 m. After living with a 2.8 optimized version of the C Sonnar for a year, I have not experienced focus issues in my work. Whether it's the C-Sonnar, or my AI'd Nikkor 50/1.4 on a SLR, (or the Cannon 50/1.2 LTM when I owned it) I only use f-stops wider than 2.0 - 2.8 for low light scenes where I am at least 4 (and usually more) meters from my subject(s). The increased DOF at this distance protects me from RF calibration errors, poor eyesight (in the case of SLR/DSLR), focus shifts and unconsciously moving the camera after obtaining focus.

I do enjoy photographing subjects in extreme low-light conditions compatible with a wide-angle view (zooming with my feet) using fast 50 mm lenses. I must say that I have never missed focus with the C-Sonnar due to the shift. When I miss focus, it's due to a lack of skill or just plain sloppy work.

When I do use a 50mm lens for close-up focusing, I use the inexpensive, plastic, but sharp, Nikkor 50/1.8 AF on my D200. This lens auto focuses well on the D200 and camera's noise and weight are irrelevant to the close up photos I like to take.

My ZI-M is with me wherever I go... it's my favorite camera, but when my subject will be closer than 3 M, I use a SLR or DSLR.

willie
__________________
"Perspective is governed by where you stand – object size and the angle of view included in the picture is determined by focal length." H.S. Newcombe

williamchuttonjr.com
  Reply With Quote

Old 12-23-2007   #7
jsuominen
Registered User
 
jsuominen is offline
Join Date: Apr 2005
Location: Finland
Age: 55
Posts: 245
Thank you Marek for your excellent test! It shows clearly that Zeiss should keep both version of C-Sonnar 50/1.5 lenses on their sales list. It would be difficult to decide, which version I would personally prefer more, if I'll buy that lens someday...

By the way, I did similar comparison - but not as clear as Marek's test - few monts ago with vintage Opton Sonnar 50/1.5 and Nikkor-S 50/1.4 lenses from 1950's. It's here if you are interested http://www.rangefinderforum.com/foru...5&postcount=14
__________________
Jari
My Gallery is almost empty - but take a look at my flickr photos
S2, Bessa T & R2S, M2 & Minilux, 35RF & 35S & AFM35, XA, Contax IIa & T2
Nikkor-S.C 5cm f/1.4, Mill. 50/1.4, 3.5cm/1.8; Summicron 50/2; CV 25/4, 28/1.9, 35/2.5 PII, 35/1.7, 50/1.5, 50/3.5 S; Rollei Sonnar 40/2.8 HFT; Zeiss-Opton Sonnar 50/1.5 T; Zeiss S-mount Sonnar 50/1.5 T*
  Reply With Quote

Old 12-24-2007   #8
nzeeman
Registered User
 
nzeeman's Avatar
 
nzeeman is offline
Join Date: Nov 2005
Location: belgrade
Age: 36
Posts: 1,124
i think this shows that sonnar is better with old 2.8 adjustment
since it dont misses that much on 1.5.
  Reply With Quote

Old 12-24-2007   #9
FanMan
Registered User
 
FanMan's Avatar
 
FanMan is offline
Join Date: Sep 2006
Location: at the edge of the Swabian Mountains
Age: 50
Posts: 145
Thanks a lot for your comparison and especially for your discussion of the results!
__________________
ZeissIkon ZI body, ZM 1.5/50, ZM 2.8/28, ZM 2.0/35, ZM 2.0/85 NIKON FM2, F3HP, Nikkor 24mm, 50mm, 35-105mm, 200mm macro Rollei 35T (my first "real" camera)
  Reply With Quote

Old 12-24-2007   #10
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
Having thought a little bit about the results of this test myself, I've actually decided to keep both lenses... However, if anyone from Zeiss will stumble on this thread, I'd like to suggest, to make a new version of the C Sonnar - with an adjustable switch between the F1.5-f2.0 range and the f 2,8-f16 range. I think this is perfectly doable with little extra engineering. This way, you could switch the best focus position as a function of your aperture, just like you adjust a FLE in one of the Hasselblad Distagons as a function of distance. This lens is a really unique tool, and I think it deserves to be used in the optimal way. An alternative, would be to make a digital rf with an electronic live view finder, where you could establish your best focus with an electronic confirmation tool ;-).
  Reply With Quote

Old 12-24-2007   #11
john_s
Registered User
 
john_s is offline
Join Date: Mar 2007
Location: Melbourne, Australia
Posts: 771
Quote:
Originally Posted by mfogiel
......... However, if anyone from Zeiss will stumble on this thread, I'd like to suggest, to make a new version of the C Sonnar - with an adjustable switch between the F1.5-f2.0 range and the f 2,8-f16 range. I think this is perfectly doable with little extra engineering. This way, you could switch the best focus position as a function of your aperture, just like you adjust a FLE in one of the Hasselblad Distagons as a function of distance......
Good idea. Or even better, have the focus ring and aperture ring linked so that the focus will be correct without the user having to switch. It would be easier than having floating elements such as are in the Summilux 50mm ASPH because the whole optical set would move as a single unit.
  Reply With Quote

Old 12-25-2007   #12
40oz
...
 
40oz is offline
Join Date: Feb 2006
Posts: 1,328
seems like only a fool would want the lens adjusted for 1.5. And pretty much anyone could figure out that at 1.5 or 2, adjust focus a bit for close distances. It's not an aperture/distance combo that most of us use a 50mm for, so it's not like it's a hassle.

I would think a switch to change focus depending on aperture would be unbelievably clunky compared to exercising a slight bit of care when focus is already tricky.

I sure as hell hope I don't end up buying a 1.5-optimized lens used.

Last edited by 40oz : 12-25-2007 at 19:36.
  Reply With Quote

Old 12-25-2007   #13
ferider
Registered User
 
ferider's Avatar
 
ferider is offline
Join Date: May 2005
Posts: 11,126
Fully agree with you, 40oz. Dealing with the shift is particularly easy
with M2 or M3 (DOF marks), but then I heard somewhere those cameras are obsolete

Also, what do you do at f2.8 and infinity ? @ f1.5 and infinity, the Sonnar behaves like
a lens-baby well, almost.

Last edited by ferider : 12-25-2007 at 19:00.
  Reply With Quote

Old 12-25-2007   #14
Doug
Moderator
 
Doug's Avatar
 
Doug is offline
Join Date: Sep 2003
Location: Pacific NW, USA
Posts: 12,147
I like John's elegant idea! But in the meantime I think I can do well with my f2.8 optimized C-Sonnar as-is. So far I have been keeping in mind the focus shift issue and just leaning forward a couple inches after focusing close-in at f2 and wider. But this is not a common situation for me, so having to compensate for error here is acceptable.

The above test is very useful in clarifying the issue, thanks! At greater focusing distances, I expect the error will stay proportional to the distance. It seems to be about 5% short at f1.5... So one solution is to focus and then turn the focus ring to a distance 5% beyond. It appears this can be done conveniently by resetting the focused distance to the left-side f4 depth-of-field mark.

In my use of the lens, I'd rather deal with this special-case in this way than be way off at f2.8 and up, which is mostly "where I live". Lovely lens.
__________________
Doug’s Gallery
RFF on Facebook
  Reply With Quote

Old 12-26-2007   #15
SDK
Exposing since 1969.
 
SDK's Avatar
 
SDK is offline
Join Date: Jun 2005
Location: Boston, MA
Posts: 444
mfogiel, I have a question. Were your cm marks scaled for the 45˚ angle of the board (so that 1cm = 1cm closer to the camera) or were they standard cm along the plane of the target board? If they are standard cm, then the errors would be about 0.7 X what is apparent because of the board angle. This would make the focus shift for the old version about 35mm at 1m focus and f/1.5, or 1.4" error.

It seems like Doug's idea about refocusing the old version wide open is good, but one might need to go less far than the left f/4 DOF mark, probably to where you might imagine the f/2.8 mark would be, about 70% of the way between the index mark and the left 4. I have the old version and will have to try that out.
__________________
Trip shutters, not people.
  Reply With Quote

Old 12-26-2007   #16
Doug
Moderator
 
Doug's Avatar
 
Doug is offline
Join Date: Sep 2003
Location: Pacific NW, USA
Posts: 12,147
Good point, SDK!
__________________
Doug’s Gallery
RFF on Facebook
  Reply With Quote

Received my Zeiss 1.5 50mm today
Old 12-29-2007   #17
peterleyenaar
Registered User
 
peterleyenaar is offline
Join Date: Apr 2007
Location: Kimberley B.C.
Posts: 31
Received my Zeiss 1.5 50mm today

Happy Holidays Folks,
I received my 1.5 50mm Sonnar today , it appears that mine is calibrated at f2.8,
the lens front focusses at f1.5.
The lens portrays considerable ca at f1.5 focussed at a distance of 20 feet, is this normal and nothing to worry about ?, I guess at some distance one would not use the lens wide open.
I'll try to figure out how to upload images and show my (primitive ) results.
O.K. the images are uploaded, first image at f1.5 focussed on the center of the bubble, second image f2.8 focussed on the center of the bubble, third image at f1.5 aproximately 20 feet.
I am unsure what to make of this , am I better off with the 50mm Planar ?
Best Regards
Peter
Attached Images
File Type: jpg L1002784.jpg (139.2 KB, 506 views)
File Type: jpg L1002785.jpg (170.8 KB, 525 views)
File Type: jpg L1002786.jpg (240.0 KB, 510 views)

Last edited by peterleyenaar : 12-29-2007 at 09:43.
  Reply With Quote

Old 12-29-2007   #18
mfogiel
Registered User
 
mfogiel's Avatar
 
mfogiel is offline
Join Date: May 2007
Location: Monaco
Posts: 4,661
SDK
The cm marks around the best focus line are symmetrical, however I don't think it makes a big difference at 1m distance - if we assume conventionally that 4cm depth is the best focus zone, the "best focus sign" should probably be 1.5cm before and 2.5 cm after that point. Anyway, the comparison was intended to show what happens on a relative basis - as far as practical application is concerned, I've found that front focusing at close distances can actually be of help if you make a portrait and you recompose the shot after setting the sharpness on the eye - I'v made many photos where the sharpness began at the ear level and behind... I am just waiting for a patient model to go through this "live" test... My opinion is, that in 80% of cases this lens works better in the "f2.8" version, however, the wide open images are a particular treat, so it is difficult to decide - as I said, I believe Zeiss could engineer this lens a bit better( and sell it for a higher price quite easily too...)
  Reply With Quote

Old 12-30-2007   #19
Mazurka
Registered User
 
Mazurka's Avatar
 
Mazurka is offline
Join Date: May 2005
Posts: 483
Quote:
Originally Posted by mfogiel
Having thought a little bit about the results of this test myself, I've actually decided to keep both lenses... However, if anyone from Zeiss will stumble on this thread, I'd like to suggest, to make a new version of the C Sonnar - with an adjustable switch between the F1.5-f2.0 range and the f 2,8-f16 range. I think this is perfectly doable with little extra engineering. This way, you could switch the best focus position as a function of your aperture, just like you adjust a FLE in one of the Hasselblad Distagons as a function of distance.
Then it wouldn't be a Sonnar design anymore -- I don't believe the classic construction can incorporate a floating element.
  Reply With Quote

Old 01-02-2008   #20
larmarv916
Registered User
 
larmarv916 is offline
Join Date: Jun 2007
Posts: 415
My complements to "Mfogiel" for his diligent efforts on creating the illustrations on the differences between the two Sonnar C's of the Zeiss ZM 50mm lenses. Very nice and effective illustrations and also helpful to see the "thumbprints" in a phyiscal and visual reference. Also I like the photos of the 2 girls as another more complex illustration of the Sonnars behavior.

Here is an example of F2.8 that is a compaion to a similar shot that was taken at F1.5 ( the F1.5 shot is posted in the thread for the Review of that lens) The Shot here is at F2.8 and still shows the Sonnars better ability at definition of 3D.




I took my son with me for the first time to Milano in March 07. We walked and shot photos with both my 50 and the 35 ZM lenses. To say he enjoyed Milano, was an understatement. He has waited to visit the Armory musuem at the Fortress was worth every dollar.




This was taken with the Zeiss 25mm...at F4 on Neopan 400

Last edited by larmarv916 : 01-06-2008 at 19:49.
  Reply With Quote

Old 02-15-2008   #21
awilder
Registered User
 
awilder is offline
Join Date: May 2005
Posts: 1,339
Thanks for a very helpful post. I recently took delivery on the f/1.5 optimized C Sonnar for use on my Hexar RF. I think the body's very slight front focus tendency (due to extra 0.04 mm film channel depth) offsets the slight back focus (WRT the subject) resulting in a small amount of front focus wide open but at f/2.8 and smaller, it's spot on using the same focus test chart as in your examples or even a distant subject at infinity. I'll post some examples in a day or so.
__________________
<a href='http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2121'>My Gallery</a>
  Reply With Quote

Old 02-15-2008   #22
Doug
Moderator
 
Doug's Avatar
 
Doug is offline
Join Date: Sep 2003
Location: Pacific NW, USA
Posts: 12,147
Quote:
Originally Posted by mfogiel
Having thought a little bit about the results of this test myself, I've actually decided to keep both lenses... However, if anyone from Zeiss will stumble on this thread, I'd like to suggest, to make a new version of the C Sonnar - with an adjustable switch between the F1.5-f2.0 range and the f 2,8-f16 range. I think this is perfectly doable with little extra engineering. This way, you could switch the best focus position as a function of your aperture, just like you adjust a FLE in one of the Hasselblad Distagons as a function of distance.
Quote:
Originally Posted by Mazurka
Then it wouldn't be a Sonnar design anymore -- I don't believe the classic construction can incorporate a floating element.
It may not take a floating element to accomplish... It might be feasible to just have the focusing cam move slightly as the aperture is changed.
__________________
Doug’s Gallery
RFF on Facebook
  Reply With Quote

Old 03-08-2008   #23
ferdhart
Registered User
 
ferdhart's Avatar
 
ferdhart is offline
Join Date: Feb 2008
Location: West Haven, CT
Posts: 4
Thanks for offering your test results. I received a C Sonnar (1.5 version) yesterday and had no problem producing the images I had hoped for. Ferdhart
  Reply With Quote

Old 05-13-2008   #24
Furachan
Registered User
 
Furachan is offline
Join Date: Dec 2007
Posts: 12
Hi all. This is my first posting on this forum.
I just came back from Hanoi where I spent a week shooting at night a lot, with an "f2.8 version" C Sonnar mostly at around F1.5. When the focus was "on", and that was a measly 25-30% of the time, the results were magical. But what about the '0%+ shots I had to throw away. This was with an Epson R-D1s by the way. I put the lens on sale in Tokyo and bought a highly dependable ZM Planar.
I already miss the extraordinary, heartbreakingly beautiful bokeh though...
One question: can anyone tell me succinctly how a pre-asph Summilux 50 compares with the Sonnar in terms of both "bokeh" and "focusing accuracy"?
Thanks!
  Reply With Quote

Old 05-14-2008   #25
gertf
Registered User
 
gertf's Avatar
 
gertf is offline
Join Date: Jun 2007
Posts: 170
Furachan,

My pre-asph summilux 50 was always spot on regardless of aperture.
  Reply With Quote

Old 05-18-2008   #26
awilder
Registered User
 
awilder is offline
Join Date: May 2005
Posts: 1,339
I agree, the focus is always spot on and the bokeh is also very nice. However, the Pre-asph. Summilux does suffer from a bit more residual astigmatism outside the central image zone requiring about f/5.6 and smaller to snuff it out. The C Sonnar doesn't have this issue and this gives it a bit of an advantage for better edge to edge sharpness at apertures of f/2.8 and smaller, something useful for critically sharp landscapes when shooting between f/2.8-5.6.
__________________
<a href='http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2121'>My Gallery</a>
  Reply With Quote

My adventure with the C-Sonnar Part II
Old 05-20-2008   #27
Furachan
Registered User
 
Furachan is offline
Join Date: Dec 2007
Posts: 12
My adventure with the C-Sonnar Part II

Well I started missing this strange and wonderful lens like crazy so I put a STOP on the sale, called Cosina HQ in Nagano, Japan and they assured me that they would gladly recalibrate the beast at around F1.5 for free and within a week...
And that's what I've done.
Why? In Hanoi I shot wide open or at F2 in near darkness and although I managed a few luminous "keepers" I lost a good 75% of the shots. I really enjoy night shooting in SE Asia, even here in Tokyo, and in order to keep the iso at 800 or 400 on my R-D1s, there is no way around using F1.5 or thereabouts. And the bokeh wide open and at F2 is wondrous.
Hope I'm not boring everyone with this tale. Thought I'd update you on the story...
Part 3 wil be the "return of the beast" newly calibrated for F1.5...
  Reply With Quote

Old 05-20-2008   #28
awilder
Registered User
 
awilder is offline
Join Date: May 2005
Posts: 1,339
I'd be very curious to see some sample images with the f/1.5 version, especially at f/1.5 and f/2.8. My concern is the possible softness between f/2.8-4 where dof may not completely cover the "new" focus shift induced at these apertures by compensating for the "old" focus shift at f/1.5.
__________________
<a href='http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2121'>My Gallery</a>
  Reply With Quote

Old 05-26-2008   #29
popobsd
Registered User
 
popobsd is offline
Join Date: Feb 2007
Posts: 21
Thanks a lot Mfogiel for your finding.
I have this lens with F2.8 version.I shot a lot wide open at night, and know this could be a big problem, I can move my lens forward a little or focus far a little to compensate the focus drift.

Here is my C sonnar 50/1.5 set on flickr

I felt unhappy when I knew my lens was a 2.8 version, Now I am very glad with it, I prefer the F2.8 version. the @F2.8 and @F4 is the most useful of this lens.

Last edited by popobsd : 05-27-2008 at 00:17.
  Reply With Quote

Old 05-28-2008   #30
Dante_Stella
Rex canum cattorumque
 
Dante_Stella's Avatar
 
Dante_Stella is offline
Join Date: Apr 2007
Posts: 1,538
If it is any comfort, this is an issue that is hardly unique to the 50/1.5 Sonnar. It's present in a lot of high-speed lenses; it's just a little more obvious because the ZM Sonnar is a very, very good lens.

The 75mm Summilux can be just as tough on an M8. After you have it recollimated for a flat sensor, you can choose to (a) have the lens (or if you prefer, the rangefinder) dead-on and ultrasharp at f/1.4 and lose usable focus at f/2-5.6 to have it return at f/8 or (b) have it focus a little bit in front wide-open and either at or a tiny bit behind everywhere else.

Try this focusing technique with the Sonnar. At f/1.5, focus from near to far and stop at the farthest distance where the RF arguably lines up. At f/2 and smaller, focus the other way and stop at the nearest distance that the RF lines up. Your break point may be f/2.4 or f/2.8, but you can figure this out pretty quickly.

On M cameras, there is also some microscopic play in the RF system that can sometimes make a difference based on the direction in which you focus. Unidirectional focusing is explicitly discussed in the instruction leaflet for the Mamiya 6 150mm lens, so it's not anecdotal or speculation.

That said, I had my 50/1.5 recalibrated in Germany - and on the second try, it worked very well.

Dante

Quote:
Originally Posted by mfogiel View Post
I've made little brackets 4cm wide, to mark the best focus zone, and put an arrow where to my eyes, the image looked sharpest.
First of all, the reference Planar shot is really quite impressive, because it really is spot on the target, i.e. the black line with the "focus here" text.

The f1.5 shots show you right away what's happening - the "new" C Sonnar looks like it's missing the precise point by 1cm, but the dof covers the best focus quite well, while the "old" version is plainly off, front focusing by about 5 cm, which is not so easy to manage in real life, making this version little usable wide open.

The f2.0 shots display a similar story, and here indeed one can see the phenomenon described by Roger Hicks and Dr Nasse - in the "new" version, the usable dof sits right behind the point of best focus. Since f2.0 is probably the most interesting aperture for low dof portraits, because it gains quite a bit of contrast with respect to wide open, yet the bokeh remains exceptional, obviously this version should perform well for the "dreamy and creamy" assignements. The "old" version is a bit like a fish out of the water here.

At f2.8 we see a capsized situation: the "new" version is disappearing behind the horizon, while the "old" starts pulling out the bite, and is entering the best overall performance zone. I suspect this lens is at it's best around f3.5, and this is where Zeiss has actually calibrated it in the first place.

At f4.0 the "new" version has become almost unuseable, while the "old" version focuses like the "new" one wide open, and, believe me, at this aperture delivers the goods in large amounts...

Finally, at f5,6 the relative best focus does not move by a detectable amount, but the dof increases, making the "new" version just useable - by f8,0 the focus stays the same and both lenses cover easily the "focus here" sign.

It is difficult to draw a definitive conclusion just on the basis of some ruler shots, and in fact I'd like to make some real portraits with both lenses, to see how it works out in practice.
However, if you are attracted to the C Sonnar for its absolute bokeh wide open, or for using it exclusively in low light and between f1.5 and f2.0, then the "new" version is for you, but you better keep another 50mm lens handy for more general shooting. On the other hand, if you like the soft but contrasty drawing with good detail, which this lens delivers between f2.8 and f4.0, plus you do not disdain great sharpnesss beyond f5.6, then the "old" version should be for you, and you might want to keep one of the older f1.4 or f1.5 lenses for the wide open soft images.
  Reply With Quote

Old 05-28-2008   #31
Rayt
Registered User
 
Rayt's Avatar
 
Rayt is offline
Join Date: Jan 2006
Posts: 1,642
Sorry...but how do you know if the lens is optimized for f/2.8 or f/1.5? Does it say on the box?
  Reply With Quote

Old 05-28-2008   #32
noimmunity
scratch my niche
 
noimmunity's Avatar
 
noimmunity is offline
Join Date: Jul 2007
Location: Lyon/Taipei
Age: 54
Posts: 3,113
It doesn't say, and apparently Zeiss cannot tell (or is not prepared to tell) from the serial number either, so you have to test the lens out. But you will find out pretty fast which it is.
__________________
jon 小強


flickr
Flickr
  Reply With Quote

Old 05-28-2008   #33
jonmanjiro
Moderator
 
jonmanjiro's Avatar
 
jonmanjiro is offline
Join Date: Feb 2007
Location: Yokohama
Posts: 4,735
Quote:
Originally Posted by noimmunity View Post
It doesn't say, and apparently Zeiss cannot tell (or is not prepared to tell) from the serial number either, so you have to test the lens out. But you will find out pretty fast which it is.
Exactly! You'll soon know if you test the lens.

I recently tested my Nikon S-mount Zeiss Sonnar 50/1.5 (as shown in this thread), and the results showed that its optimised for f2.8, and front focuses at f1.5 and f2. Though the front focus isn't nearly as bad as I was expecting it to be.
  Reply With Quote

Old 05-29-2008   #34
awilder
Registered User
 
awilder is offline
Join Date: May 2005
Posts: 1,339
According to Tony Rose, he pre-tests every 50/1.5 C Sonnar he sells with an M8 to verify which version it is.
__________________
<a href='http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2121'>My Gallery</a>
  Reply With Quote

Old 11-23-2008   #35
TJV
Registered User
 
TJV is offline
Join Date: Nov 2006
Location: Cloud Nine
Posts: 594
So I've revived this old thread from the ashes...

To those who are still using this lens, how about posting some shots here that prove the focus shift issue is only of very minor importance, able to be tamed, along with a note as to which version you own.

I'd love to see more examples so I can compare the Zeiss with my Summicron.
  Reply With Quote

Old 11-24-2008   #36
abenner
undecided
 
abenner is offline
Join Date: Nov 2006
Location: Omaha
Posts: 347
I had a Sonnar which I sold and didn't know which version it was. I think it was 2.8. Regardless I contacted Zeiss about adjusting it if needed, etc, and got this nice response. Thought I'd share it for those interested:

thanks for your request.
It is not possible to know about the calibration of a lens by its serial number.
Depending on the type of camera in use, the tolerances of the rangefinder and flange focal adjustment of the camera, and the preferred f-stop you are using you will get slightly different results regarding focusing accuracy.
So please make some tests with your camera to decide if you would have get the lens readjusted. Only a few photographers felt that another kind of adjustment of their C-Sonnar lens would fit better to their demands until now.

If you´d like to get your lens recalibrated, you can contact our representative in the US:

Carl Zeiss MicroImaging, Inc.
(Regional Distribution Partner)
Photo Division
One Zeiss Drive
10594 Thornwood / NY
Phone: +1 800 543 1033

[email protected]
USA


or you can send your lens directly to us. Therefore, please fill out the following repair form and add it together with the neccessary documents (warranty card, copy of the invoice) to the shipment:




Here is some further information about the classic C-Sonnar lens:

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.

If the C Sonnar T* 1,5/50 ZM should predominantly be used at full aperture, in a few cases a recalibration of the lens to f/1.5 might be necessary to minimize focus shift at full aperture. Together with this calibration to f/1.5 comes an increase of the focus shift at f/2.8 and smaller, but this will be covered by the depth-of-field in most cases.
Because the results of the focus shift of the C Sonnar in practical use depend on different factors (e.g. on the calibration of the flange focal distance and rangefinder of the camera body in use, the preferred distances and f stops, the 3-dimensionality of the subject etc), we strongly recommend to make individual test shots with a C Sonnar before you decide to send it in for recalibration.

In most cases, a recalibration of the lens is not necessary.

If you´d like to get your lens recalibrated, you have the following alternatives:

-return it to the dealer where you purchased it, so he can send in the lens to us
-send it to our distributor in the country of purchase
-send it to us (Carl Zeiss Germany), if you have an European warranty card that came with your lens
-send it to Cosina, Japan, if a Japanese warranty card was included

The recalibration is free of charge as long as the lens is covered by warranty.



Best Regards

Bertram Hönlinger
  Reply With Quote

Old 11-24-2008   #37
TJV
Registered User
 
TJV is offline
Join Date: Nov 2006
Location: Cloud Nine
Posts: 594
Thanks Abenner.
I emailed Tony at Pop Flash to check to see if they are still coming out of the factory at f2.8 and he says they are. They will only receive ones set to f1.5 upon special request.
It's interesting because I also emailed B&H and they stated that all new ones are set to f1.5. Either way, I'd sooner trust the guys at Pop Flash.
In real world terms I doubt It'd matter anyway. My type of photography doesn't usually allow for 100% accurate focusing, it's too hurried.
  Reply With Quote

Old 11-24-2008   #38
gertf
Registered User
 
gertf's Avatar
 
gertf is offline
Join Date: Jun 2007
Posts: 170
TJV, I bought mine from Tony and it is the 2.8 version as far as I can tell. Have not noticed any focus shift so far.
  Reply With Quote

Old 11-24-2008   #39
TJV
Registered User
 
TJV is offline
Join Date: Nov 2006
Location: Cloud Nine
Posts: 594
I'm pretty much decided I'll get the lens and don't mind a 2.8 version. Actually, I think I'd prefer it set to 2.8.
It's actually hard to find decent examples of what the lens can do on the internet and seeing as there isn't anyone in NZ that stocks ZM or Zeiss lenses next to impossible to judge what it's like for myself. Think it's just time to take the plunge!
  Reply With Quote

Old 11-25-2008   #40
morback
Martin N. Hinze
 
morback's Avatar
 
morback is offline
Join Date: Sep 2008
Location: İstanbul
Posts: 512
I'm still in the process of taming the focus shift. I have not found the proper amount of leaning necessary to be spot on.
I have Tony's 2.8 even though he/they thought it would be 1.5 optimized.
I like it better that way, and it makes for a characterful lense. I rarely use it at 1.5 and if I do, I bracket it to 2.8! Better safe than sorry!

Check flickr for images, maybe I'll post one here when I get home tonight. Not sure if it's the "Sonnar-look" (never owned a sonnar before of any kind/age), but I love the character.
  Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 17:10.


vBulletin skin developed by: eXtremepixels
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

All content on this site is Copyright Protected and owned by its respective owner. You may link to content on this site but you may not reproduce any of it in whole or part without written consent from its owner.