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The differences of Zeiss lenses..Planar,Tessar,Flektogon....
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PostPosted: Mon Dec 10, 2007 3:48 pm    Post subject: The differences of Zeiss lenses..Planar,Tessar,Flektogon.... Reply with quote
Hi,

Excuse my dumb ass question, but I would like to know briefly what are the pro / the cons and main differences between the well most know Zeiss lenses :

Planar
Tessar
Flektogon
Distagon

Thanks Embarassed


PostPosted: Mon Dec 10, 2007 3:54 pm    Post subject: Reply with quote
They are cover different areas (focal length) and they have different lens design.

for example Flektogon is wide angle


PostPosted: Mon Dec 10, 2007 3:58 pm    Post subject: Reply with quote
These different names designate different optical schemes.

Planar is a scheme based on a double gauss couple, this scheme is very old (invented in the 19th century) but was not practically useable until lens coating was invented, because the large glass-air surfaces produced a conspicuous loss of luminosity.

Tessar is a scheme based on 4 lenses, invented at the beginning of 20th century (some say as an evolution of Cooke's triplet) and very succesfull, because allows for great optical results and cheap construction. It is most certainly the most used optical scheme in the history of lens industry and it is still used today in many compact point and shoot cameras.

Sonnar is a more complex optical scheme with more glasses than Planar but less glass-air surfaces, and for this reason was largely used instead of Planar before the lens coating was invented. Today, it is nearly abandoned as the progress in the lens making is able to control the negative side effects of Planars while keeping the advantages.

Distagon is a very complex lens scheme that is used for wide angle lenses. It can count up to 10 elements or even more. It's importance compared to older Biogon scheme is that Distagon is retrofocus and thus allows for use also with mirror reflex cameras. It is also more uniform in the optical rendition from centre to edges compared to Biogon. On the other side, Biogon is unrivalled for sharpness but due to fact that the rear lens must nearly touch the film plane, it is unuseable for reflex cameras, except for those cameras (such as some Nikon models) that allow for permanent lockup of mirror. In that case, a Biogon-like lens can be mounted and the reflex view replaced by a viewfinder to mount on flash shoe. This is what Voigtlaender has done with some of their super wide angle lenses.

All these optical schemes were invented by Zeiss engineers and their names are patented, this is why you can only find them in Zeiss lenses. However other makers copied them abundantly and for instance you find these optical schemes in many Russian lenses and also in some Japanese lenses such as the early Nikkors, only difference is that they had to use different names due to copyright.
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PostPosted: Mon Dec 10, 2007 4:25 pm    Post subject: Reply with quote
Thank you all Very Happy


PostPosted: Mon Dec 10, 2007 5:16 pm    Post subject: Reply with quote
Very well explained, Orio.

Let me just add that...

...the Planar (from GE "plan" = flat) design is used for very fast "normal" and short tele lenses.
...Bertele developed the Sonnar (from GE "Sonne" = sun) design to fast "normal" and tele lenses.
...the name "Flektogon" derives from LAT "flectere" = to bend and GR "gonia" = angle.

Source: Hartmut Thiele: Carl Zeiss Jena, 2007.

Wink


PostPosted: Mon Dec 10, 2007 5:42 pm    Post subject: Reply with quote
I provided a link in this post,
http://forum.mflenses.com/viewtopic.php?t=3214

The direct link to different Zeiss designs are,
http://www.panix.com/~zone/photo/czlens.htm


PostPosted: Tue Dec 11, 2007 12:50 am    Post subject: Reply with quote
Well I’ll continue the naiveté of lens designs and ask this question: since planers, pancolars, and biotars are all double gauss derivatives…what is it that actually separates these lenses quality wise? And how exactly are different designs adapted to different focal lenths? Do they just change the size, thickness, and spaces between the elements/groups until they can call it something different?

Thanks in advance
~Marc


PostPosted: Tue Dec 11, 2007 12:54 am    Post subject: Reply with quote
themoleman342 wrote:
Well I’ll continue the naiveté of lens designs and ask this question: since planers, pancolars, and biotars are all double gauss derivatives…what is it that actually separates these lenses quality wise? And how exactly are different designs adapted to different focal lenths? Do they just change the size, thickness, and spaces between the elements/groups until they can call it something different?
Thanks in advance
~Marc


I don't have the technical knowledge to answer this. Maybe Veijo can.

The only thing that I am sure to tell you is, little calculation changes can make enormous difference with lenses. In the end of 19th-beginning of 20th century, when there was no computer to design lenses, a development time of 5 YEARS was common for developing a new lens. Such is the complexity of the calculations.
So I think that even with identical, or nearly identical lens designs, differences in calculations, in optical glass quality, in coating treatment, can make a tremendous impact on the final quality of the lens.

As for the more specific differences between the designs that you mentioned, I leave the answer to more qualified people.

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PostPosted: Sun Oct 03, 2010 4:34 am    Post subject: Reply with quote
Another interesting thread from the basement....care to add to the posts on this...any new insights into the differences for the next generation of new users!!
Thanks


PostPosted: Sun Oct 03, 2010 5:15 am    Post subject: Reply with quote
Great explanation by Orio.

However, let's be fair; if we're going to accuse other companies for stealing Zeiss designs (which they do), then we must agree that Zeiss stole P. Angenieux's retrofocus design, no? Very Happy


PostPosted: Sun Oct 03, 2010 10:12 am    Post subject: Reply with quote
rawhead wrote:
Great explanation by Orio.

However, let's be fair; if we're going to accuse other companies for stealing Zeiss designs (which they do), then we must agree that Zeiss stole P. Angenieux's retrofocus design, no? Very Happy


Indeed, Rawhead!
I think we should make a difference between copying and stealing.
Copying is when you take somebody else's work and reproduce it verbatim.
Such is what Russians did with many pre-war Zeiss lenses, e.g. the Helios-44 which is a verbatim copy of the Biotar 58/2
Stealing is when you take somebody else's good idea and use it to develop your own creation.
Such is what, for instance, Canon did when they built their own 55mm f/1.2 lens basing it on the Planar design.
I think Zeiss in this case belongs to the second category: they used Angenieux's idea to build their own retrofocal lenses (and did a great job at that).

Pablo Picasso once said: "Good artists copy; great artists steal".

I think that sentence says all that there is to say Wink


PostPosted: Sun Oct 03, 2010 10:35 am    Post subject: Reply with quote
Going on from the original question:- Where do all the other primary lenses from Canon, Pentax, Minolta, Olympus and so on and so on, fit in and do the lenses have construction/design names like Zeiss......also if Zeiss designs/inventions were the best why would any other lens designer bother designing/calculating anything different....well excluding f0.95 to f1.2
And has any one listed the different constructions of primary lenses and why/if they are different from different names, as my thinking is:- if I worked at Pentax, and say Nikon bought out a new excellent lens, I'd go to the shop and buy it, take it apart and copy it, working around any possible patent.


PostPosted: Sun Oct 03, 2010 10:55 am    Post subject: Reply with quote
Excalibur wrote:
also if Zeiss designs/inventions were the best why would any other lens designer bother designing/calculating anything different....


Well, as first thing, nothing is ever perfect.

Secondly, recalculations are needed by a lot of reasons. For instance, a change of materials in the glass requires recomputation, as it happened to the Planar 2/135 after certain elements like lead and chromium were banned form use in lenses.
Obviously evey makers use it's own materials for the glass and this requires recomputation to optimize the scheme for the materials.

Just an example why the values of the glass materials are more important than the lens names: the Planar 2/135 is more similar to a Sonnar scheme than to a Planar scheme. Yet, the designers called it Planar because of the light refractive properties that are Planar-like.
P.S. Thanks to Marco Cavina who provided me with this information.
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