Zeiss and Schneider designs, same?

[msbarnes]

I don't know too much about optics but the xenar performs like a tessar and the xenotar performs likes a planar. People usually treat them as equals, so my question is: do these lenses share the same exact design? There are probably other instances but this spring up to mind because I'm looking for a Rollei (and I don't care who makes the lens, personally).

I was a bit confused because I thought that Leica and Zeiss didn't share the same designs because of patent laws (e.g. summarit a response to the sonnar), but if this is the case, then why is it that Schneider and Zeiss have shared the same designs (assuming that they do)?

 

[Roger Hicks]

Same? No. Similar? Often.

Cheers,

R.

 

[BobYIL]

I don't know too much about optics but the xenar performs like a tessar and the xenotar performs likes a planar. People usually treat them as equals, so my question is: do these lenses share the same exact design? There are probably other instances but this spring up to mind because I'm looking for a Rollei (and I don't care who makes the lens, personally).

I was a bit confused because I thought that Leica and Zeiss didn't share the same designs because of patent laws (e.g. summarit a response to the sonnar), but if this is the case, then why is it that Schneider and Zeiss have shared the same designs (assuming that they do)?

The Xenar is a Tessar design (Leica Elmar too) comprised of four elements in three groups.

The Xenotar is a modified double-Gauss design with 5 elements in four groups (always, as far as I know..)

The Planar is again a double-Gauss one, from 5 to 6 elements for Rolleiflex models or 6 to 7 elements for Hasselblad Planars. Below is different Planar designs employed with Rolleiflex models however, as you see, they are not the same as the Xenotar design.

6-element Planar. (With small modifications ZM Planar as well.)

For more information about several Rolleiflex models, refer to:

http://www.rolleigraphy.org/rolleiflex_compare.html