Huck Finn
Well-known
Sonnar2 said:
There's no "maybe" about it, the Zeiss Ikon was not developed out of the Bessa R2A/3A in any way. The comment in the review was a completely false statement.
Mazurka
Well-known
The "response from Zeiss" as quoted in LL reads suspiciously like nonsense from a typical marketing dept. It's especially ridiculous when compared with the Zeiss claim that the ZM lenses are "Superior in every way", because they "are specifically designed to minimize focus shift with aperture changes – an important innovation with big benefits for rangefinder photography", and that they are "designed with a wear resistant filter mount and an extremely accurate rangefinder coupling mechanism ... Reduces unintended focus shift with aperture variation for improved accuracy of rangefinder defined focus." http://www.zeissikon.com/lenses.htm
dazedgonebye said:
The CV 21 is and always has been coupled.
FanMan
Established
Mazurka said:
Everything in this story is strange. The lens test announcing right in the beginning that results are "anecdotal at best", the missing of test shots, the short time lag between our discussion and the (official?) Zeiss response (but maybe there was another "derogatory" discussion elsewhere on the Internet), the fact that such "information for dealers and users is not published on the official Zeiss page.
Huck Finn
Well-known
It occurs to me that there are two factors that may have affected the issue of focus shift in the test report as compared with user experiences reported here.
First, the tests were done with an M8 whereas most user experiences here have been with film cameras. Because of the crop factor, depth of field on a digital camera is different than DOF on a film camera for the same field of view, The DOF with a digital camera is thinner. In general, the problem of focus shift is greater as depth of field is reduced
Second, the authors never discussed the shooting conditions under which the the focus shift was observed. As depth of field is reduced with smaller shooting distances, focus shift would again become increasingly problematic. Users here who have been shooting wide open at 10 feet would not experience issues with focus shift in the same way that someone shooting at 3 feet would. In fact, anyone shooting under the latter conditions might be surprised to find that there is an issue at all.
First, the tests were done with an M8 whereas most user experiences here have been with film cameras. Because of the crop factor, depth of field on a digital camera is different than DOF on a film camera for the same field of view, The DOF with a digital camera is thinner. In general, the problem of focus shift is greater as depth of field is reduced
Second, the authors never discussed the shooting conditions under which the the focus shift was observed. As depth of field is reduced with smaller shooting distances, focus shift would again become increasingly problematic. Users here who have been shooting wide open at 10 feet would not experience issues with focus shift in the same way that someone shooting at 3 feet would. In fact, anyone shooting under the latter conditions might be surprised to find that there is an issue at all.
jano
Evil Bokeh
rxmd said:
Perhaps it fits the "standard distribution" -- i.e. the typical person using the lens will not use it at 1.5 100% of the time, quite possibly stopped down a majority of the time. So it would provide a balance as to being "good enough" near that aperture *shrug* Just a wild guess here on my part, I know very little about optics.
Huck Finn
Well-known
I found the following comment from Zeiss posted on another site which adds some detail to the one that LL posted:
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. This is expressed by the additional letter "C" in the name of the lens. It helps to achieve pictures with a special artistic touch. This lens draws your subject in a fine, flattering, a little bit glorifying way. It renders a sharpness which is a little bit rounded being less aggressive than in contemporary lens designs, but not soft. A lot of famous portraits shot of glamorous and prominent people of the 1930's used this effect. It gives the portrayed person something shining, nearly celestial. This effect is very well balanced, not exaggerated. Therefore many viewers see it in a subconscious way. The trained observer, however, knows why and enjoys it.
Provided that the lens is used with f-stops wider than f/2.8 the images are a bit similar to images that one can get with the soft filter ZEISS SOFTAR. The C-Sonnar T* 1.5/50 ZM, however, avoids some disadvantages in these softeners in the out-of-focus background area. When one makes a lens with such features, one has to pay for that and has to accept the following side effects:
1. Compared to the PLANAR type of the same focal length the C-SONNAR is less corrected for a flat field.
2. The C-SONNAR T* 1.5/50 ZM has a distinct focus shift when stepped down; this means that the focal plane "wanders" when the distance setting remains unchanged but the lens is stepped down. this focus shift occurs particularly in the near range.
3. The depth of field at high apertures of such a lens is slightly higher than with modern designs.
Field curvature is not necessarily a disadvantage in shooting 3-dimensional subjects. The "wandering " of the focal plane needs special considerations. When the lens is stopped down from wide open to medium apertures, the focal plane in the object space is shifted toward the background. (For example: from 5 to 6 meters when the lens is stopped down to f/4). Therefore the rangefinder cannot be easily corrected for all f-stops.
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 to f/5.6 or to use the PLANAR 2/50 T* ZM lens.
Dated: January 16, 2007
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. This is expressed by the additional letter "C" in the name of the lens. It helps to achieve pictures with a special artistic touch. This lens draws your subject in a fine, flattering, a little bit glorifying way. It renders a sharpness which is a little bit rounded being less aggressive than in contemporary lens designs, but not soft. A lot of famous portraits shot of glamorous and prominent people of the 1930's used this effect. It gives the portrayed person something shining, nearly celestial. This effect is very well balanced, not exaggerated. Therefore many viewers see it in a subconscious way. The trained observer, however, knows why and enjoys it.
Provided that the lens is used with f-stops wider than f/2.8 the images are a bit similar to images that one can get with the soft filter ZEISS SOFTAR. The C-Sonnar T* 1.5/50 ZM, however, avoids some disadvantages in these softeners in the out-of-focus background area. When one makes a lens with such features, one has to pay for that and has to accept the following side effects:
1. Compared to the PLANAR type of the same focal length the C-SONNAR is less corrected for a flat field.
2. The C-SONNAR T* 1.5/50 ZM has a distinct focus shift when stepped down; this means that the focal plane "wanders" when the distance setting remains unchanged but the lens is stepped down. this focus shift occurs particularly in the near range.
3. The depth of field at high apertures of such a lens is slightly higher than with modern designs.
Field curvature is not necessarily a disadvantage in shooting 3-dimensional subjects. The "wandering " of the focal plane needs special considerations. When the lens is stopped down from wide open to medium apertures, the focal plane in the object space is shifted toward the background. (For example: from 5 to 6 meters when the lens is stopped down to f/4). Therefore the rangefinder cannot be easily corrected for all f-stops.
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 to f/5.6 or to use the PLANAR 2/50 T* ZM lens.
Dated: January 16, 2007
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Huck Finn
Well-known
jano said:
I think that your speculation makes some sense. The old Noctilux also experienced a problem with focus shift. It was known as being great at f/1, but then was uselsess until f/5.6 where the depth of field was great enough to cover the focus error.
It sounds like Zeiss has chosen f/2.8 so that the lens will be usable at all apertures. While there will be some focus shift at f/1.5, the user might be able to learn to work iwth it or to adjust/compensate for it. Sebastel reported that the tech said that the lens could be adjusted so that there would be no focus shift at f/1.5. My guess is that the price that one would pay for that would be that other wide apertures would be unusable as you stopped down until you get to f/5.6.
As you suggest f/2.8 would seem to be the mid point & therefore the point at which the best compromise could be made for general usage. For anyone who has specialized uses in mind, Sebastel's comment suggests that Zeiss can adjust the lens differently. I see now why they are building the 85/2 Sonnar with floating elements.
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dazedgonebye
Veteran
rover said:
My point exactly....
The review initially stated that it was not, but that fact was forgiveable considering the price of the lens.
That bit has been removed.
john_nyc
Established
Interesting how this review has precipitated so many comments. I think all of this really underscores two important points:
1. Equipment reviews should never be taken as gospel, no matter who's writing them. Every reviewer has their own preconceptions, opinions, and personal history. People also make mistakes. Being human, I think it'd be impossible for any review to be 100% objective and every review to be 100% accurate. In the specific case of LL, I think their reviews are heavily opinionated. But, it's their website and they have every right to express their opions, good/bad/indifferent. Grains of salt should be ingested as required.
2. Lens selection is so highly subjective that any review is of limited value. It reminds me of the old Brian Eno quote, "Writing about music is like dancing about architecture". The proof, as they say, is in the pudding. If there was only one way to make a lens, then there would only exist one lens design in any given focal length. As I think someone else mentioned, why does Leica then currently have no fewer than four 50mm lenses in M mount? Sure you can generate objective data on lens performance using controlled lab techniques. But, is that why camera lenses exist? And, like people, isn't often lens' imperfections that give them character and individuality?
I personally own a ZM Sonnar-C. I think it's a great lens and it definitely has a special "look". I haven't noticed any significant focus problems at any aperture that I've shot it at. At least nothing that couldn't have also been attributed to shooting handheld with a very shallow DoF on a NYC street.
That said, I'm going to be putting it up for sale in the next couple of days. Why? I came across an old book of prints I made when I used to have a Wetzlar 'Lux 50. I got nostalgic and found a good deal on another one. I can't afford to keep more than one lens of each length. Else I'd still have the Planar and the Nokton in addition to this Sonnar and the "new" 'Lux. Each of them has something that makes them special in their own way.
Sorry for rambling.. I just think it's interesting...
1. Equipment reviews should never be taken as gospel, no matter who's writing them. Every reviewer has their own preconceptions, opinions, and personal history. People also make mistakes. Being human, I think it'd be impossible for any review to be 100% objective and every review to be 100% accurate. In the specific case of LL, I think their reviews are heavily opinionated. But, it's their website and they have every right to express their opions, good/bad/indifferent. Grains of salt should be ingested as required.
2. Lens selection is so highly subjective that any review is of limited value. It reminds me of the old Brian Eno quote, "Writing about music is like dancing about architecture". The proof, as they say, is in the pudding. If there was only one way to make a lens, then there would only exist one lens design in any given focal length. As I think someone else mentioned, why does Leica then currently have no fewer than four 50mm lenses in M mount? Sure you can generate objective data on lens performance using controlled lab techniques. But, is that why camera lenses exist? And, like people, isn't often lens' imperfections that give them character and individuality?
I personally own a ZM Sonnar-C. I think it's a great lens and it definitely has a special "look". I haven't noticed any significant focus problems at any aperture that I've shot it at. At least nothing that couldn't have also been attributed to shooting handheld with a very shallow DoF on a NYC street.
That said, I'm going to be putting it up for sale in the next couple of days. Why? I came across an old book of prints I made when I used to have a Wetzlar 'Lux 50. I got nostalgic and found a good deal on another one. I can't afford to keep more than one lens of each length. Else I'd still have the Planar and the Nokton in addition to this Sonnar and the "new" 'Lux. Each of them has something that makes them special in their own way.
Sorry for rambling.. I just think it's interesting...
nasmformyzombie
Registered
dazedgonebye said:
I don't think so. This demonstrates at the least sloppiness on the part of the reviewer, and at worse, just another indication that they have no idea what they're talking about reference RF photo gear. LL have an agenda, and that is to promote digital gear and companies who manufacture it. The factual errors and poor scientific rigor of the review are just appalling. The reviewer did an exceptionally poor job no matter how you cut it.
Mazurka
Well-known
Huck Finn said:
It's funny how 50-year-old Sonnars, whether 50 or 85mm, never seem to suffer from focus shift.
For that matter, Leica counterparts at these focal lengths have no such problems either. My pre-ASPH 90 Cron focuses perfectly, even at 1m and f/2.Has anyone considered the fact that the so-called "focus shift" of the C Sonnar could be a product of sloppy focussing or RF maladjustment?
As for floating elements, they aim to reduce SEIDEL's five aberrations (spherical aberration, coma, astigmatism, curvature of field, distortion) and chromatic aberrations at close range, not focus shift. When Nikon introduced them (as CRC) some forty years ago, only their wideangles have them. http://www.nikon.co.jp/main/eng/portfolio/about/history/nikkor/n14_e.htm Focus shift is much less a problem for SLR lenses than RF counterparts. Wideangles, with their increased DOF, even less so.
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Huck Finn
Well-known
Mazurka said:
Interesting . . . Are you saying that focus shift was an unknown phenomenon 50 years ago? And that Zeiss invented it with the introduction of these new lenses?
Trius
Waiting on Maitani
I recall that Zuiko macros, the 21/2 and likely others had floating elements just for that reason.Mazurka said:
jano
Evil Bokeh
Huck Finn said:Interesting . . . Are you saying that focus shift was an unknown phenomenon 50 years ago? And that Zeiss invented it with the introduction of these new lenses?
I think that's what he's saying. Truth be told: my new 50 sonnar is very good wide open.. I have a mix of sharp and soft images wide open, and I've attributed that to my natural body movements while taking a photo (I waver forward/back, it's kinda funny). However, my little two week adventure with a 1930's uncoated 50 1.5 sonnar had much sharper results, and I'd go so far as to say, better. I decided to go with the newer lens, though, since, well.. it's new, and I like new, but I've been toying with going back to the pre-war stuff because I fell in love with it then. I disliked the contax camera, it was just a PITA to use, but the gass... with an m-adapter... mmmm
Maybe the issue wasn't known back then because there wasn't wide-spread testing and user-interaction like there is now. However, it's interesting to consider we don't see these kinds of statements with the other, fast-modern lenses (and if we do, they are typically QA issues). Zeiss has presented it as a design feature (clever, haha), and if that really is the case, then the use of the sonnar would sort of become limited to specific applications by those who are aware of the charecteristics. For the users unaware of or apathetic towards this (like me), it's just another somewhat expensive lens to take pictures with
Mazurka
Well-known
Huck Finn said:Interesting . . . Are you saying that focus shift was an unknown phenomenon 50 years ago? And that Zeiss invented it with the introduction of these new lenses?
Huck, this leap of yours is bigger than Agent Mulder's.
I'm saying Zeiss dealt with focus shift effectively half a century ago. Why can't they do it now? Remember, they still claim otherwise here: http://www.zeissikon.com/lenses.htm
I agree with FanMan and Gary. Nothing about the LL coverage on the C Sonnar sounds right -- and that includes the alleged response from Zeiss. And I thought Erwin Puts was bad.
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sebastel
coarse art umbrascriptor
Mazurka said:
please keep in mind that focus shift is a consequence of spherical abberation.
still i doubt that floating elements will really help with focus shift in general.
but that's just my 1.6 eurocent
sebastel
Mazurka
Well-known
sebastel said:
Like I said, floating elements are designed for something else: http://www.nikon.co.jp/main/eng/portfolio/about/history/nikkor/nwords-e.htm#floating
Huck Finn
Well-known
Interesting stuff, guys. I've been trying to avoid delving too much into a theoretical discussion about focus shift, etc. & taking this thread off in a different direction, but since there are now several posts about it, here are my thoughts just to offer my 2 cents.
Mazzurka, the older Sonnars did have issues with focus shift. Focus shift doesn't necessarily manifest itself as dramatically as it has in this case. It typically shows up just as a softening of the image. The older Sonnars by different manufacturers were adjusted for optimal performance differently by each manufacturer & therefore showed different performance features. Zeiss has made their own choices in this modern version & we'll see how users like it.
The fact that Nikon introduced CRC to address issues with wide angle lenses does not mean that these are the only lenses which benefit from floating elements nor that focus shift is not a factor & can also benefit from the use of floating elements in certain circumstances. Please see the link below (that I previously posted in this thread) that explains the relationship between focus shift & spherical aberrations and the use of floating elements to correct the problem.
www.vanwalree.com/optics/spherical.html
Zeiss has long been a proponent of floating elements to correct for focus shift errors in fast lenses at close distances. In fact some have attributed the introduction of floating elements in Zeiss M lenses to the influence of Coenen after he moved from Zeiss to Leica.
The fact is that floating elements have been used in lenses of every focal length. Although floating elements can be found in the design of a number of modern telephoto lenses, Leica found other solutions with the 90/2 AA, but they have used floating elements in both the 50/1.4 M-Summilux and the 75/2 M-Summicron.
Finally, with regard to Zeiss's marketing claims that their ZM lenses are corrected for focus shift, it seems to me to be evident that this marketing claim was written 3 years ago with regard to the new line of lenses that were being introduced at Photokina at that time - not with regard to this new Sonnar that was introduced a couple of years later.
However, I don't think that this let's them off the hook. There is nothing "alleged" about the Luminous Landscape update report of a communication from Zeiss about the issues that LL found in their testing. I found the same information originating from Zeiss with even more detail published elsewhere on the internet & I posted it earlier in this thread.
The import of this communication from Zeiss showing up in two different sources is that they obviously have had their marketing statement available & prepared well before questions that were posed to them from at least two different sources this month. Given your legitimate & astute highlight of the contradiction between their original marketing material about ccrrection for focus shift & the more recent introduction of a lens not corredted for this same problem - with explanations after the lens was issued of the fact that it is not corrected for focus shift, I feel that it was incumbent on Zeiss to have published this information about the C-Sonnar before they released this lens & before consumers made their purchasing decisions. If Zeiss regarded it as a classical reissue of a "special lens" best used for "articstic images, portraist, & atmospheric landscapes," they should have said so in their initial material about it rather than calling it "a very versatile lens for photojournalistic work in general and for available light photography in particular."
This was a bad job by Zeiss in my opinion since they apparently already knew differently. They should have said that the C-Sonnar was an exception to the rest of the highly corrected lens line, that it was a lens offering a classical look for those who were specifically interested in that look in M-mount. They should have said that it has some issues to work around as they now do. If they didn't know differently earlier & this was a hasty revision of their marketing statements, then it was a bad job by their technical staff for not properly testing the lens or for not properly communicating its limits to management.
Cheers,
Huck
Mazzurka, the older Sonnars did have issues with focus shift. Focus shift doesn't necessarily manifest itself as dramatically as it has in this case. It typically shows up just as a softening of the image. The older Sonnars by different manufacturers were adjusted for optimal performance differently by each manufacturer & therefore showed different performance features. Zeiss has made their own choices in this modern version & we'll see how users like it.
The fact that Nikon introduced CRC to address issues with wide angle lenses does not mean that these are the only lenses which benefit from floating elements nor that focus shift is not a factor & can also benefit from the use of floating elements in certain circumstances. Please see the link below (that I previously posted in this thread) that explains the relationship between focus shift & spherical aberrations and the use of floating elements to correct the problem.
www.vanwalree.com/optics/spherical.html
Zeiss has long been a proponent of floating elements to correct for focus shift errors in fast lenses at close distances. In fact some have attributed the introduction of floating elements in Zeiss M lenses to the influence of Coenen after he moved from Zeiss to Leica.
The fact is that floating elements have been used in lenses of every focal length. Although floating elements can be found in the design of a number of modern telephoto lenses, Leica found other solutions with the 90/2 AA, but they have used floating elements in both the 50/1.4 M-Summilux and the 75/2 M-Summicron.
Finally, with regard to Zeiss's marketing claims that their ZM lenses are corrected for focus shift, it seems to me to be evident that this marketing claim was written 3 years ago with regard to the new line of lenses that were being introduced at Photokina at that time - not with regard to this new Sonnar that was introduced a couple of years later.
However, I don't think that this let's them off the hook. There is nothing "alleged" about the Luminous Landscape update report of a communication from Zeiss about the issues that LL found in their testing. I found the same information originating from Zeiss with even more detail published elsewhere on the internet & I posted it earlier in this thread.
The import of this communication from Zeiss showing up in two different sources is that they obviously have had their marketing statement available & prepared well before questions that were posed to them from at least two different sources this month. Given your legitimate & astute highlight of the contradiction between their original marketing material about ccrrection for focus shift & the more recent introduction of a lens not corredted for this same problem - with explanations after the lens was issued of the fact that it is not corrected for focus shift, I feel that it was incumbent on Zeiss to have published this information about the C-Sonnar before they released this lens & before consumers made their purchasing decisions. If Zeiss regarded it as a classical reissue of a "special lens" best used for "articstic images, portraist, & atmospheric landscapes," they should have said so in their initial material about it rather than calling it "a very versatile lens for photojournalistic work in general and for available light photography in particular."
This was a bad job by Zeiss in my opinion since they apparently already knew differently. They should have said that the C-Sonnar was an exception to the rest of the highly corrected lens line, that it was a lens offering a classical look for those who were specifically interested in that look in M-mount. They should have said that it has some issues to work around as they now do. If they didn't know differently earlier & this was a hasty revision of their marketing statements, then it was a bad job by their technical staff for not properly testing the lens or for not properly communicating its limits to management.
Cheers,
Huck
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awilder
Alan Wilder
Well said Huck. I'm curious as to whether the focus shift issue is less prominant at long distances ( say 20ft and beyond) for landscape photography when shot at f/1.5? Anyone out there with focus shift problems try this yet?