Contax-Zeiss 21mm lens

[DCP]

Seems to me that Kobayashi -san is such a vintage freak that, if the 21mm were a homage to the Biogon, he would have said so. I can't help thinking that being grouped together on flickr isn't good evidence for the lenses being related.

Not that it matters... but from a practical point of view the VC 21mm and 25mm vignette, especially on the R-D1, whereas the new Biogon designs are much better, which was another reason I'd be surprised by a relationship between them. Altho, of course, Zeiss have also been accused of being cavalier about model names.

Being grouped together is not good evidence for being related, of course. However, not forgetting that Cosina does manufacture lenses for Zeiss and Voigtlander (et al).. , it is possible that the wides of the Voigtlanders are 'off-springs' from CZ influence. If you look at the CV21 and CZ21, you have to admit the resemblance in element positioning is uncanny. I think the main features as stated previously is the protruding rear element so close to the focal plane and the symmetrical element layout and it is these that give these Biogons their reputation. I believe this is the 'Biogon' design that the Flickr group admin is talking about and why he/she made the assumption.

PS.. I'm not saying that the CV is equivalent to the CZ. All I'm saying is they have similarities in design that seem to give them similar optical qualities. Personally, I'm for the CZ 🙂

 

[DCP]

My sense without any real expertise, is that Zeiss has not always been very scientific or technical when matching lens names with lens designs. The Biogon name is also used for their 35/2.8 from the 1930s, and this lens behaves very differently from the 21/4.5 of the 1950s. The 21/2.8 may use a different formula entirely (I don't know)..

Germans are the most hard-assed scientific/technical people I know of (intended as a compliment) and I doubt they would be lax about naming conventions (and they are proud of being technical and engineering perfectionists).

The 35 2.8 IMHO does resemble the biogon designs.

(From http://www.auspiciousdragon.net/siliceous/wp-content/uploads/2007/05/p1000533_web500x.jpg)

 

[outfitter]

I doubt they would be lax about naming conventions

Lax has nothing to do with it; marketing has everything to do with it. Somewhere along the line Zeiss shifted from using names to denote actual lens formulas to generic trade names. As it stands today the name Biogon is meaningless save to connote a Zeiss designed (but not necessarily made) wide angle lens. Zeiss is trying to evoke its past glory while ceding manufacturing to a relatively minor Japanese maker.

I resent the fact that today a Zeiss Biogon is not a Zeiss Biogon but just another 21mm lens - it may be as good or better but the name Biogon no longer guarantees the lens will have the original Biogon qualities and is confusing. From the reviews I've read of the modern "Biogon" lenses they don't seem to command the same sort of cult status as the original which has withstood the test of time to an amazing degree - a non MC superwide over fifty years old and still viable.

Michael

 

[Paul T.]

I respectfully disagree! And of course, image is all a matter of perception.

I think Zeiss have entered what is indisputably a very cult market, and retained a great deal of prestige, for their wide-angles in particular seem to be very well thought of. One could argue that same is not quite true of the Ikon, given the 15 per cent rate of problems seen in the rff poll, but there are many people who seem to think that the Cosina-made lenses are just as high quality as Leica's offerings.

Ultimately, one has to ask, do we all benefit from having Zeiss lenses available at an affordable price? I would think we do, and personally if I can have a 21/4,5 Zeiss design that will fit on an M3 (or R-D1, or M8), I will be a happy bunny.

 

[outfitter]

I am certainly an admirer of Zeiss lenses; I regularly use Contax RF cameras with a fullish compliment of Zeiss glass and I have almost a complete run of Zeiss SLR lenses in Rollei QBM mounts (many of the same lenses used on the Contax SLRs) which I also use regularly as well as Zeiss glass on my Hasselblads - heck I even occasionally use pre-war folding plate film cameras with Tessars.

I was not impugning the abilities of Cosina or the quality of the modern lenses bearing the Zeiss name. I was expressing my regrets at the confussion caused by using old names on new formulas - the discussion on this thread is a prime example of the confusion this has engendered. In the old days everyone knew what a tessar, biotar, sonnar or biogon was- their strong points, their limitations and their pictorial effects. I think in the past people were more preoccupied with the unique characteristics of each formula; it was useful for example to know that a sonnar or heliar produced one effect wide open (thanks to spherical aberation) and another closed down. There is no perfect lens and one way or the other we are still choosing the distortions that produce the type of image we prefer. Through the years Zeiss has maintained its unique "look" my precisely juggling these tradeoffs.

 

[Paul T.]

I absolutely take your point, I'm no expert on lens designs, so accept that on some lenses those traditional names are probably there for marketing reasons. But I do applaud the fact that they have reintroduced some classic designs such as the 50/1.5 Sonnar and, I would guess, the 21/4.5 Bioogn.

I personally find one aspect of Zeiss's marketing amusing, namely the emphaiss they placed, when launching the ZM lens line, on 'minimising focus shift with aperture.' I remember at the time thinking, Is that such a problem with modern lenses? And, of course, the only modern lens that seems to have that problem is... a ZM Sonnar!

 

[outfitter]

BTW your avatar shows Dr Eric Salomon holding an Ernostar 85mm f1.8 lens (attached to the Ermanox camera). Ludwig Bertele worked at Ernemann and was the designer of the f/2 & f/1.8 Ernostars that were used on the Ermanox. When Ernemann was absorbed by Zeiss Ikon, Bertele went on to design the Sonnar, which was based on his f/1.8 Ernostar.

Michael

 

[Paul T.]

Glad you recognised it. Not only did they design great lenses in those days, they dressed properly, too.

 

[Rico]

... I personally find one aspect of Zeiss's marketing amusing, namely the emphaiss they placed, when launching the ZM lens line, on 'minimising focus shift with aperture.' I remember at the time thinking, Is that such a problem with modern lenses? And, of course, the only modern lens that seems to have that problem is... a ZM Sonnar!

Another modern lens has joined the club: Canon EF 50/1.2L. 🙁 Released a few months ago, this EF was on my shopping list to replace a middling EF 50/1.4, but the focus shift is too extreme. Canon can correct the problem with firmware if they so choose.

I was also disappointed by the S50 ZM focus shift. It was going to be my first CZ lens for RF (I have many for the Contax RTS).

 

[outfitter]

The Zm Sonnar isn't the same formula as the original Sonnar, as it's in 4 groups, not 3 - contrary to what some people have written on the web the old lens was difficult and expensive to make because of the extreme curves of some of the elements and ther new design looks more economical.

The original 50/1.5 Sonnar design is pleasantly soft in the corners wide open which can have a nice effect with closeup portraits as the focus gradually softens from the point of focus until the backaground has that wonderful bokah the lens is noted for. The problem was that a lens can only be collimated at one distance (usually infinity) and that means that with a RF camera the focus is off at minimum distance and it is not covered by depth of field wide open with a f1.5 lens (which some call a focus shift; others just say the lens isn't sharp wide open). Once the photographer knew the actual point of focus under these conditions he could compensate (like focusing on the ears instead of the eyes) and get breathtaking results wide open - which was even more spectacular in the days when ASA12 was a fast film.

Zeiss evokes the well known characteristics of the old Sonnar as an explanation of the "problem" with its new lens but I don't know if the characteristics are the same. That in a nutshell is my complaint, when the Sonnar isn't the Sonnar but a derivative design are we talking about the same lens or a new probelm introduced by the new dersign?

I'm afraid that collimating the ZM Sonnar to focus at close distances will not please everyone and Bertele's brilliant design will get a bad rap as "not being up to modern lenses". The original Sonnar produces a "look" and you work with the know characteristics of the design; either like it or don't but it isn't about "modern is better".

Michael

 

[varjag]

Sonnar design lens consists of three functional groups, with specific proportion of negative/positive strengths in them. It doesn't matter if a group has an air space in it as long as it holds its combined strength.

For a given design, the amount of elements in a group is largely dictated by abberation correction requirements and optical glass catalogue available to desinger. Original Sonnars were made with 5 (2/85) and even 4 (4/135) elements, because longer focal lengths reduce magnitude of abberations in Sonnar design. Yet all Sonnars show same disposition of optical strengths among the groups.

Then, air element still has a refractive index and two surfaces, and allows for a degree of correction as well.

Hence it's not entirely fair to dismiss C-Sonnar based on just element count. Ludwig Bertele in early 1930s had only old Schott glass catalogue to work with, which lacks many kinds of modern optical glass. Also, air element was less of an option because it created extra two surfaces in the lens, which was prohibitive in the era before coatings. Bertele did what he had to do, but it doesn't mean that current Zeiss designers have to stick to 1930s tech as well. That 7-element lens is harder to manufacture than 6-element doesn't imply it is inherently better.

As of the softness of original Sonnar in the corners, some part of it is due to curvature of field: it sure ain't a Planar 🙂 So focus is often not where one would expect it after looking at the image center. This is less an issue on long distances of course.

 

[outfitter]

Bertele did what he had to do, but it doesn't mean that current Zeiss designers have to stick to 1930s tech as well. That 7-element lens is harder to manufacture than 6-element doesn't imply it is inherently better.

As of the softness of original Sonnar in the corners, some part of it is due to curvature of field: it sure ain't a Planar 🙂 So focus is often not where one would expect it after looking at the image center. This is less an issue on long distances of course.

My comments were not addressed to the issue of whether the ZM Sonnar is a good lens just that what Bertele did for better or worse was a Sonnar and in my book the modern ZM lens is something else (i accept Zeiss' term "derivative") with its own pluses and minuses, but the name thing only introduces confussion.

I look for a lens that actually adds something to the picture. Total optical transparency and freedom from aberration is best left to the lens testing laboratory. Photographing people requires different aesthetics, techniques and equipment. I like the old Sonnar, some people want newer designs - to me the real fault line is between those who spend their time discussing lens tests and those who go out and take pictures. Fortunately this forum seems to be dominated by picture takers.

Michael

 

[varjag]

Michael, it would be not entirely correct to assume that I spend any noticeable amount of time doing lens tests 🙂

I'm fond of 1.5/50 Sonnar too, it's a lens in its own league. My point was that it C-Sonnar is still a Sonnar.

 

[outfitter]

Michael, it would be not entirely correct to assume that I spend any noticeable amount of time doing lens tests

Eugene,
Never crossed my mind

Michael

 

[outfitter]

My point was that it C-Sonnar is still a Sonnar.

So is the 180mm f2.8 but very different characteristics, especially wide open. Everybody seems to be discussing the C-Sonnar in terms of the old 50mm F1.5 - is that apposite? I don't know.

Michael

 

[icebear]

Like the pictures !

Like the pictures !

I've shot several rolls with the 2.8/21mm Biogon. Because images say more than words:

http://Contax G2

Hi toyotadesigner,

eventhough the G2 version doesn't fit M-mount that doesn't make your pictures anything less than stunning. Great stuff ! Much more enjoyable than the detailed lens design discussion - just MHO 😀

 

[outfitter]

Hi toyotadesigner,

Much more enjoyable than the detailed lens design discussion - just MHO 😀

I'm not much taken with static snaps of inanimate objects - I guess it's live and let live.🙄