Lens Front and Rear Element Numbers

[Smitty]

Hello,

I have a Protar V11- 13 3/4" in Koilos shutter. I have noticed that the front and rear element numbers do not match. I guess that the obvious would be that something got changed out at some point...seems to focus ok.
Thoughts?

Thanks, Steve

[ridax]

As it is a double anastigmat, don't worry. The cells are corrected independently of each other, and you can safely use them in any combinations. Even the double anastigmat cells of different types are perfectly combinable.

[Smitty]

Great, thank you. Bausch & Lomb Protar is considered to be a good lens correct? I am guessing that the Koilos shutter must be quite old. In searching it seems that there were all sorts of lenses fitted to this shutter...

[ridax]

Bausch & Lomb was and is a reputable manufacturer. That's why they had the opportunity to buy that Zeiss patent. Zeiss did not sell any rights to manufacture their lenses to the firms that could spoil the Zeiss reputation. I owned a B&L Zeiss Protar for several years and was totally satisfied by its performance.

[J. Patric Dahlen]

The cells have individual serial numbers from the factory, and this type of lenses were sometimes sold in sets of three or more cells with a list of focal lengths for the different combinations.

A Bausch & Lomb catalog from 1904: https://www.pacificrimcamera.com/rl/00591/00591.pdf

And as you can see, B&L were proud to have the licenses to produce lenses by Zeiss designs.

Bausch & Lomb-Zeiss Protar f-12.S Series VII.
The lenses in Series VII are the component elements which are combined to form the Convertible Protars, Series VIla. They are listed separately with a view of facilitating the selection of assorted sets of these lenses. Each single Anastigmat, by means of a special adapter, fits either end of the lens mount.