10.5cm f4.5 skopar in a 6x9 plate camera question

<p>guys<br>

the net said its a tessar type<br>

so I screwed the lenses to see for myself... theres just 2 thick ones<br>

is it a tessar type because the 2 front elements are glued together instead of an air space like Zeiss<br>

regards Andrew</p>

<p>5 seconds' Googling :-) would have revealed that a classic Tessar<br>

https://www.google.co.uk/search?q=tessar+lens+diagram&espv=2&biw=1777&bih=887&tbm=isch&imgil=-g4H4UOEo0ccLM%253A%253BhR4LbPmqRHgyoM%253Bhttp%25253A%25252F%25252Fen.wikipedia.org%25252Fwiki%25252FHistory_of_photographic_lens_design&source=iu&pf=m&fir=-g4H4UOEo0ccLM%253A%252ChR4LbPmqRHgyoM%252C_&usg=__9eJMJzHe8K7O02PUBP37qB3mHA4%3D&dpr=0.9&ved=0CDgQyjc&ei=r1EjVZ6-C4XWUaa7gsAK#imgrc=-g4H4UOEo0ccLM%253A%3BhR4LbPmqRHgyoM%3Bhttp%253A%252F%252Fupload.wikimedia.org%252Fwikipedia%252Fcommons%252Fthumb%252F0%252F01%252FZeissTessar-text.svg%252F220px-ZeissTessar-text.svg.png%3Bhttp%253A%252F%252Fen.wikipedia.org%252Fwiki%252FHistory_of_photographic_lens_design%3B220%3B245<br>

has two groups, each of two elements. The front group is air-spaced, the rear cemented.<br>

The same goes for a Skopar:<br>

https://www.google.co.uk/search?q=skopar+lens+design&espv=2&biw=1600&bih=799&tbm=isch&tbo=u&source=univ&sa=X&ei=3lMjVeX2EczzUrTwgugP&ved=0CDoQsAQ#imgdii=_&imgrc=IML9XHQ6_NFUdM%253A%3BgDlQwIT_UsYHwM%3Bhttp%253A%252F%252Fwww.taunusreiter.de%252FCameras%252FSkopar_chroma.jpg%3Bhttp%253A%252F%252Fwww.taunusreiter.de%252FCameras%252FBessa_RF_histo_dt.html%3B400%3B455</p>

<p>Andrew, the cemented doublet is the lens' rear group, the pair of air-spaced doublets is its front group. You (or someone else) switched them around.</p>

David, In case you are wondering about that large space in your post. The https link lettering was so long that it would have run across the right hand column with ads and list of articles. There were no spaces in all that link lettering so it couldn't wrap. It had to wait to get to the bottom where there was no right hand column to run into.

<p>Andrew, here's a link that shows a Skopar lens taken apart:<br /> http://forum.mflenses.com/voigtlander-braunschweig-anastigmat-skopar-105mm-f4-5-repair-t41439.html</p>

<p><em>that large space in your post.</em><br>

Thanks, James. The links were ridiculously long but in terms of information content they were the best I could find!</p>

Would have worked, David, if you had wrapped a hyperlink tag around the link:<br><a href="https://www.google.co.uk/search?q=tessar+lens+diagram&espv=2&biw=1777&bih=887&tbm=isch&imgil=-g4H4UOEo0ccLM%253A%253BhR4LbPmqRHgyoM%253Bhttp%25253A%25252F%25252Fen.wikipedia.org%25252Fwiki%25252FHistory_of_photographic_lens_design&source=iu&pf=m&fir=-g4H4UOEo0ccLM%253A%252ChR4LbPmqRHgyoM%252C_&usg=__9eJMJzHe8K7O02PUBP37qB3mHA4%3D&dpr=0.9&ved=0CDgQyjc&ei=r1EjVZ6-C4XWUaa7gsAK#imgrc=-g4H4UOEo0ccLM%253A%3BhR4LbPmqRHgyoM%3Bhttp%253A%252F%252Fupload.wikimedia.org%252Fwikipedia%252Fcommons%252Fthumb%252F0%252F01%252FZeissTessar-text.svg%252F220px-ZeissTessar-text.svg.png%3Bhttp%253A%252F%252Fen.wikipedia.org%252Fwiki%252FHistory_of_photographic_lens_design%3B220%3B245">Link.</a><br><br>Only two groups means it is not a Tessar.<br>But there may have been many different designs called Skopar, including Tessar-types: <a href="https://www.google.co.uk/search?q=tessar+lens+diagram&espv=2&biw=1777&bih=887&tbm=isch&imgil=-g4H4UOEo0ccLM%253A%253BhR4LbPmqRHgyoM%253Bhttp%25253A%25252F%25252Fen.wikipedia.org%25252Fwiki%25252FHistory_of_photographic_lens_design&source=iu&pf=m&fir=-g4H4UOEo0ccLM%253A%252ChR4LbPmqRHgyoM%252C_&usg=__9eJMJzHe8K7O02PUBP37qB3mHA4%3D&dpr=0.9&ved=0CDgQyjc&ei=r1EjVZ6-C4XWUaa7gsAK#tbm=isch&q=skopar+lens+diagram">Link.</a>

<p>I can't find an example of a Skopar as you describe. Yours sounds more like the Voigtlander Kollinear type. As QD de B says however it is clear that Voigtlander did not strictly apply lens names to specific lens layouts. Instead they used their lens names more like trade names to cover a class of lens. So you can get a 4-glass and a 5-glass Heliar for example.<br>

Or maybe someone has fiddled with it. Does it produce a clear image?</p>

<p>Don't understand either one of the above statements. Firstly, a Tessar is without doubt a 4-element lens with 2 groups, the front one air-spaced, the rear pair cemented. Secondly, this<br /> https://www.google.co.uk/search?tbm=isch&q=skopar+lens+diagram&ei=Le4kVfbNBoL8UM-ChKgF#imgrc=rlxbgMXdXX5sfM%253A%3BLYN00O9XK3yceM%3Bhttp%253A%252F%252Fwww.taunusreiter.de%252FCameras%252Fskopar_z.jpg%3Bhttp%253A%252F%252Fwuyuan68.blog.163.com%252Fblog%252Fstatic%252F561118002007112112436968%252F%3B200%3B150<br /> clearly shows a Tessar-type design which was designated a Skopar. CC correctly states that Voigtlander may well not have been very strict in their use of the name Skopar, to the extent that not all Skopars are Tessar-type designs, but that's something else!</p>

This was discussed and some of the usual suspects participated.

 

http://www.photo.net/classic-cameras-forum/00M8v8?start=10

 

Though I like the name reuse theory ... I would like hard proof. There are plenty of these out there I suspect

( what vintage Andrew?) and the known triplet designs are known so why Skopar for a triplet design .I will

visit some of these links .. My curiosity has been piqued!

 

Andrew.. pictures please.

David, hinges on what you what call a group. As the name suggests, the Tessar has four elements: two cemented into a group; two free standing, allowing the use of their relative spacing to be used in the design. I'd not call those two free elements a group.<br>You could also look at the assembly and call the bit that comes out of the mount from in front of, and the bit that comes out of the assembly from behind the diaphragm a group. I wouldn't. But than there are two groups.<br>But it doesn't matter.<br><br>Just two thick lenses, or perhaps two cemented groups, does mean it is not a Tessar typ.

<p>guys<br>

ill post photos of the camera tomorrow as I just got home and its 1 am<br>

it looks to me like 2 cemented groups but ill post photos of the lenses too<br>

I don't want to cause any trouble<br>

Anfdrew</p>

<p><em>Just two thick lenses, or perhaps two cemented groups, does mean it is not a Tessar typ.</em><br>

Absolutely correct. Most people do use the word "group" as I do, to indicate sub-assemblies which are then combined to form a lens. The best-known example of a lens with two groups which is NOT a Tessar is the rapid rectilinear type, which has two identical groups, both cemented. Or possibly the 6-element double-Gauss AKA plasmat type, with two identical cemented groups, each with 3 elements.</p>