Apertures for Zeiss Triple Convertible

[Edison]

You are referring to the "VII" on each lens bezel, right?

This has nothing to do with series VII filters. What you have is a pair of Series VII Protars. The Series VII was Dr. Paul Rudolph's final version of of the Protar (typically labeled on the bezel "Protarlinse"). It consisted of four glass elements cemented together, you can see the configuration in the appropriate Zeiss catalogs on the camera eccentric website. When two Series VII Protars are paired up in a shutter or barrel, probably the more common way they were used, Zeiss referred to the combination as a Series VIIa objective, also their literature would refer to this combination as a "Double Protar." The single component, the Series VII had a maximum aperture of f/12.5.
The "Series VIIa" or "Double Protar" was "faster" than either of its components. A symmetrical combination (both cells the same focal length) is the "fastest". My circa 1933 Zeiss catalog shows two 29 cm Protars combined to give a 17 cm f/6.3 objective; a 29 + 22 cm combination gave a 14.5 cm f/7 objective and 29 + 18 cm yielded a 13 cm f/7.7 objective.

Each Series VII Protar had its own serial number. Based on four samples in my records, when the combination was symmetrical the serial numbers were consecutive; e.g. two 59 cm cells, serial numbers 918934 and 918935. When the two cells are of different focal lengths the serial numbers of course will not be consecutive.

Based on several samples and dating them according to Hartmut Thiele's Fabrikationsbuch Photooptik II Carl Zeiss Jena it looks like Zeiss stopped including the "VII" on the bezels of these Protars about 1929-1930. I think the wide angle f/18 Protar continued to be marked with a "V". Don't know offhand what Bausch & Lomb's practice was.

This is probably more than anyone wanted to know...

David

Mine does not say series anything. They are in mm. They are in a barrel with a helicoid. And the thread size appears to be 35.5mm. It’s interesting how this one is a bit different then most. Is D.R.P. somehow for Dr Paul Rudolph?

[Vaidotas]

To make things more complicated on series VII Protars.
Keep in mind, that Carl Zeiss Jena made Protarlinse (or Protar lens) cells and dedicated barrels in a variety of different so called "slip over" sizes.
This is important to anyone who plans to add additional cells to existing setup.
Let's say 22 cm cell was made in three different "slip over" sizes - 27, 32, 37 mm.
Best reference is CZJ 1933 catalogue on Camera Eccentric site.

[ridax]

D.R.P. is for Deutsches Reich Patent.

[j.e.simmons]

And to make it even more complicated, I have a Series VII 240mm lens with VIII on the barrel. It’s an indicator of the barrel size.

[Edison]

To make things more complicated on series VII Protars.
Keep in mind, that Carl Zeiss Jena made Protarlinse (or Protar lens) cells and dedicated barrels in a variety of different so called "slip over" sizes.
This is important to anyone who plans to add additional cells to existing setup.
Let's say 22 cm cell was made in three different "slip over" sizes - 27, 32, 37 mm.
Best reference is CZJ 1933 catalogue on Camera Eccentric site.

Good lord. The double protar 22/29 has slip over covers of 42 and 37. I just measured mine and the OD of the 285 is 37mm and the OD of the barrel (actually is the aperture ring) is 47mm.

Something else I noticed is vignetting like in this picture (it’s very slightly cropped and the original was a little heavier. I think it could be from using the helicoid to focus. I’ll have to pay more attention next time.

[David Lindquist]

Mine does not say series anything. They are in mm. They are in a barrel with a helicoid. And the thread size appears to be 35.5mm. It’s interesting how this one is a bit different then most. Is D.R.P. somehow for Dr Paul Rudolph?

Zeiss gave each subsequent design of the Protar a series number, rendered as a roman numeral. The Series VII was the last design. They only engraved the roman numeral, not the word "Series" (which probably would have gotten the German spelling "Serie") on the lens. From examples I've seen they stopped marking the Series VII Protars with "VII" circa 1929-1930. So if they got to Series VII, were there a Series VI, V, IV, III, II and I? Certainly there was the Series V, their f/18 (very) wide angle lens. Don't know about the others. I think I've seen reference to a Series IV. Also there was something called the Ortho-Protar.

ridax has explained D.R.P. After WWII in West Germany this became D.B.P. for Deutsches Bundespatent.

David

[Edison]

Zeiss gave each subsequent design of the Protar a series number, rendered as a roman numeral. The Series VII was the last design. They only engraved the roman numeral, not the word "Series" (which probably would have gotten the German spelling "Serie") on the lens. From examples I've seen they stopped marking the Series VII Protars with "VII" circa 1929-1930. So if they got to Series VII, were there a Series VI, V, IV, III, II and I? Certainly there was the Series V, their f/18 (very) wide angle lens. Don't know about the others. I think I've seen reference to a Series IV. Also there was something called the Ortho-Protar.

ridax has explained D.R.P. After WWII in West Germany this became D.B.P. for Deutsches Bundespatent.

David

So would the lack of VII mean it’s post 1929? I heard earlier that since it’s in mm rather than cm it’s pre-1910.

[Edison]

I designed a hood with a filter slot for this particular barrel.

You can find it uploaded here.

[ridax]

I like the design. But I would not use a protector unless (1) I want to lower the single-cell's contrast to make it equal to the contrast of the complete double-anastigmat; or (2) the filter is multi-coated.

[Edison]

I like the design. But I would not use a protector unless (1) I want to lower the single-cell's contrast to make it equal to the contrast of the complete double-anastigmat; or (2) the filter is multi-coated.

Thanks. Do you mean the uv filter specifically? If so It’s just something to test the size with. I’m planning to use a yellow 8 filter (will get a 15 sometime) when using the single cell. I admit a bit of the filter details are over my head. I’m not sure that a yellow 8 will be a good idea to cut the chromatic aberration. Im equally concerned about protecting the naked aperture.