What's with all the names? Aren't these all made by the same company? Zeiss, Contax etc? I'm fairly new to the alt gear and it's interesting but it would be nice to know more about it. They all come in different mounts, I get the ZE,ZF thing.
The name "Sonnar" is derived from the German word "Sonne", meaning sun. It was given this name because its large aperture (f/2.0) made it considerably brighter than many other lenses available at the time.
Planar is a symmetric 6 element design. Double Gauss.
Sonnar is a non-symmetric design with a specific arrangement of elements. The traditional layout can be seen on Dante Stella's website (amongst other places). Newer lenses with the Sonnar name don't necessarily have the traditional layout.
Both the Planar and Sonnar are Zeiss designs - they came up with both of them. Other makers make lenses with similar designs now.
Distagon as far as I can tell is Zeiss's name for retrofocus wide angles, while there more symmetric designs are caleld Biogons.
"Contax" on these forums usually refers to the line of 35mm "Contax/Yashica" or "CY" mount SLRs, which were a joint venture between Zeiss and Kyocera. There are also a few other Contax-branded cameras/lenses (also Zeiss and/or Kyocera products but not CY mount) that you will occasionally see mentioned, such as the "Contax N" autofocus SLR system or "Contax 645" 6x4.5cm medium-format cameras.
"Planar" is a name Zeiss uses for a family of lenses with similar near-symmetrical designs, using 6 (100/2, 85/1.4) or 7 (50/1.4, 50/1.7) elements. Symmetrical lens designs have advantages in canceling out many common lens aberrations (things that degrade sharpness or distort image geometry).
"Sonnar" is another name Zeiss uses for a family of similar lens designs. Sonnar lens designs use fewer glass elements glued together into fewer groups than Planars, so there are fewer air/glass transitions (at the expense of slightly less well corrected aberrations). This was especially important before the development of good multicoating technologies --- an uncoated glass/air surface will reflect back ~12% of the light that hits it, which rapidly adds up to cause serious problems. However, with modern multicoatings that can reduce surface reflections to < 0.1% (such as Zeiss' famous "T*" coatings), lens designs with lots and lots of elements are possible (limited by cost more than internal reflections). When Sonnar lenses were first introduced, they were considered "fast" by 1930s/40s standards. Sonnar lenses today, however, tend to be slow compared to their Planar counterparts (e.g. Sonnar 85/2.8 vs. Planar 85/1.4, Sonnar 100/3.5 vs. Planar 100/2), with their advantages being lighter weight and lower price.
Symmetrical lens designs have their elements positioned approximately around the nominal length of the lens away from the camera film/sensor (e.g. a 50mm Planar design has lens elements around ~50mm from the film plane). This makes symmetrical wide-angle designs impossible to use on an SLR, since a 21mm symmetrical design would need to sit where the mirror goes. Instead, for wide angle SLR lenses, highly asymmetrical "retrofocus" designs are necessary, which move the rear element of the lens far enough from the film to give room for the mirror. Zeiss tends to indicate retrofocus design lenses by the name "Distagon."
Telephoto lenses actually use the same design principles as retrofocus designs, but turned around backwards, to allow a "long" lens to be shorter than its nominal length (e.g. so a 400mm lens doesn't have to stick out 400mm from the camera). Hence you may sometimes hear the term "reverse telephoto" used in place of "retrofocus".
mpmendenhall wrote:
Sonnar lenses today, however, tend to be slow compared to their Planar counterparts (e.g. Sonnar 85/2.8 vs. Planar 85/1.4, Sonnar 100/3.5 vs. Planar 100/2), with their advantages being lighter weight and lower price.
The exception to this rule is rangefinder lenses, where Sonnar designs are just as fast as Planar designs, and far more compact.
The Original wartime Sonnar are 50mm f/1.5 and 50mm f/2.0. The Russian Jupiter-3 is a common copy of the f/1.5, some even made with schott glass taken in reparations after the war.
The Nikon S mount 50/1.4 is a Sonnar design, as is the Canon LTM 50/1.5. The amazing Zunow 50/1.1 is a Sonnar design (and priced accordingly) and a couple of odd rarer lenses like the MS-OPTICAL 50/1.3 are Sonnar designs.
Sonnars, because of their beautiful rendering, a combination of the lack of corrected spherical aberration and wavey focus plane (imagine ripples from a drop of water) are highly sought after and tend to command higher prices. This despite their lower sharpness and less clinical rendering, gofigure
Not many 'real' Tessar's around these days are there? Isn't it a modified Cooke Triplet design?
There's a Zeiss ZM 85/4 Tessar which is a true triplet. All the other *current* lenses are Vario-Tessar's that have little in common with the original Tessar design. Even the C/Y and N tele-tessar's aren't 'real' tessar's.
The Leica Elmar 50/2.8 is a Tessar. Another classic Tessar are the f/3.5 lenses on Rolleiflexes. I'm pretty sure there are some Zeiss Tessars for C/Y - the pancake? From my reading, the Tessar is not actually a modified Cooke Triplet. A good book for this stuff is Kingslake's "A history of the photographic lens."
The Tessar design is typically 4 elements in 3 groups, e.g. the Contax Tessar 45/2.8. The small number of elements lends itself well to very compact pancake lenses. I think Zeiss owns the rights to the name "Tessar," but other manufacturers have made Tessar-style lenses (e.g. Nikon 45/2.8 pancake), especially for non-interchangeable-lens compact cameras.
Mirek Elsner wrote:
What construction is the Voigtlander Ultron 40mm and other ~40mm pancakes?
The Oly 40/2 pancake looks a lot like a Planar design to me (with 6 elements in 6 groups).
The Voigtlander Ultron 40/2 uses an aspherical element, which places it in a slightly different category from "classic" all-spherical lens designs (though its 6 element / 5 group design likely derives from a Planar, with the aspherical surfaces kicking in improved correction for spherical aberration without sacrificing bokeh). The increasing availability of affordable aspheric lenses, exotic glasses, and computer optimization means that lens designs are likely to break away from variations on the tried-and-true iconic designs (Planar, Sonnar, Tessar, etc.) that dominated the previous century.
Mirek Elsner wrote:
What construction is the Voigtlander Ultron 40mm and other ~40mm pancakes?
As far as I understand, lenses that fit in these designations were for the most part designed by hand or at least used a previous lens design as a starting point. So you can trace the evolution of these lenses. This is why the Tessar is not in fact a descendant of the Cooke Triplet - the evolution to the Tessar design took a different route and the designer made notes of his progression. Likewise, while the Heliar looks very similar to the Tessar, it IS a descendant of the Cooke Triplet. Now we can look at these lenses and see their similarites.
Modern lenses might be very loosely based on a given design scheme, but with lens design programs, designers can really play around with different elements, etc. So most modern lenses don't quite fit into these categories, unless a specific effort is made to do so (like the Zeiss ZM 50/1.5 Sonnar). Double Gauss designs (most 50mm lenses) are probably the exception. I think this also plays a part in why the designations on newer lenses don't quite mean as much. The Zeiss ZM 85/2 Sonnar is a good example of that.
So, my take on all this naming stuff is that it's almost more about design progression and lineage than anything else, which plays less of a role in modern lenses. Some companies (like Leica) just name based on max aperture. Others, like Cosina, seem to just use historical names any way they please, with a few exceptions.
kidtexas wrote:
The Leica Elmar 50/2.8 is a Tessar. Another classic Tessar are the f/3.5 lenses on Rolleiflexes. I'm pretty sure there are some Zeiss Tessars for C/Y - the pancake? From my reading, the Tessar is not actually a modified Cooke Triplet. A good book for this stuff is Kingslake's "A history of the photographic lens."
The 45/2.8 Tessar is a true Tessar, I must have missed it
The Cooke Triplet dates to 1893, the Zeiss tessar dates to 1902. The difference is cementing an additional element into the rear group, otherwise identical. Wikipedia gives a much more elaborate and glorifying (to Paul Rudolph - Zeiss designer) path to discovery, but no matter his path to the Tessar design, it is extremely similar to a Cooke Triplet.
Similarly the Heliar design is like a Tessar with a cemented doublet at the front as well as the back, but they do admit their lineage to the Cooke Triplet.
Cableaddict wrote:
While we're on the subject, someone should explain Jenna & Flektagon.
-Great read, BTW. I'm kind of wondering why no company has come out with a "Sonnar" plugin for Photoshop!
Jena is a place, in East germany (before the fall of the Berlin Wall) that housed a Zeiss factory. Aus Jena means "from Jena".
Flektogon's are retrofocal wide angles, but *look* to be consistently 6 or 7 group designs. I don't know anything else, can't find any resources, I'd put it in the same boat as Distagon.
RE: Sonnar plugin, it's already in there! Duplicate Layer, Gaussian blur 50px or so, set layer opacity to about 20%, voila! I jest, classic Sonnars have a little fairy inside that sprinkles magic onto every image made with the lens.
