Protar lenses?

[Bill_1856]

Can someone explain to be about Zeiss Protar lenses?
I know that Symmars and Turner-Reich lenses are used in combinations of front, rear, or both elements. How is the Protar different? Or is it like a casket set, with different combinations of elements?
What focal lengths did they come in? Were any of them coated?
Thanks

[goamules]

If you mean the Protar VIIa they are a little of both. You can use the single element alone, or use both like the Turner Reich. Sometimes they were sold with the same focal length front and rear, not different ones. But it was also common for people to buy an extra element or two of different focal lengths, so it's like a casket set. The speeds varied depending on if you had the same focal length front and rear, or different ones. Jim Galli has a good explanation of the speeds here somewhere. Also, see the B&L catalog on Cameraeccentric, it explains a lot.

[Jim Galli]

First of all Protar doesn't really mean anything. It's a brand name like Ektar was. Lot's of different purposed Ektars etc. Protar's came in Series numbers. The most common ones and the ones that were produced the longest were Series V which is wide angle 110 degrees, Series IV wide field which is 90 degrees, and Series VII which is the convertible.

Series VII seems to be what you're asking about. Looking at the 1912 Bausch & Lomb catalog helps to figure out how they worked. The individual cells were 4 element 1 group and were corrected for single use. You didn't need two opposing symmetrical cells to get all of your corrections like a Dagor.

So you could mix and match only hindered by size constraints. They were f12.5 as a single lens behind an aperture. If you combined 2 back to back that were the same size, like 2 16 1/8" cells, you had a superb 9 1/4" f6.3 lens. The cells made logical steps up and down. 8 3/4", 11 3/16", 13 3/4", 16 1/8", 18 3/4", 23 ?/?", 27" etc etc. with smaller ones and bigger ones. You usually only spanned a couple of steps in your combinations. If you spanned 1 step, like an 16 1/8" and a 13 3/4" together it was an 8 1/2" lens at f7. If you spanned 2 steps like the 18 3/4" and 27" it was an f7.7 lens combined.

And yes, they offered some sets that were like a casket set. A 'C' set had 3 sizes with a common barrel that had aperture scales for all the possibles, and a 'D' set had 4 I believe. Sometimes you see the german sets with a barrel or shutter that's just marked in millimeters. Mix what you will, you look at the mm of aperture and divide into whatever your focal length you combined was.

[renes]

I just bought 170mm f/6.3 Protar with two 290mm cells and I am going to find & buy another Double-Protar but 105mm f/6.3 which consist of two 183mm cells. Confirm please, if I join 290mm single element with 183mm (at rear) I will get about 130mm f/6.3, right? What other single element Protar I need to get 200mm Double-Protar and what f-stop it will has? Will this cell fit to the shutter of my 170mm Double-Protar?

[Steven Tribe]

Cameraeccentric has lists of the various VIIa combinations and the different F values.
I am not certain that the various licencees of the Zeiss design have the same thread sizes for the same and different focal lengths.
I recall having seen a note that there is a limit to the performance that be expected when mixing series VII cells of very different focal lengths?