Seeking lens info: Ross London 14 1/2 f/11?

[David Brunell]

I pulled the trigger on an old empire state 8x10 at a great price and this came with it.



After an exhaustive search I can't seem to find any information on it and could use some help.

Thanks, Dave.

[Steven Tribe]

This is a very easy lens to misinterprete as the cells are marked with the single cells data (just like the Zeiss Protar series VII). That is, the front cell is F11 with a focal length of 14.5" - but with both cells, it becomes an F5.5 with a much shorter focal length.
So what looks like a process lens is actually a Ross Combinable F5.5 (or part of).
VM (from CCHarrison) has the background in the lengthy Ross section.
How is the aperture marked and the rear lens rim?

[David Brunell]

Thanks Steven, I sent the seller a message as I don't have it in my possesion yet. From what I have seen on this page under the description that matches the f.11 14 1/2" it further confuses me as it refers to "single component" that does not change the focal legth or aperature?

http://www.allenrumme.com/lensdb/Convertible.html

[Steven Tribe]

It has been used as a single lens so as to cover the 8x10 plate. The original lens, with both cells in place, would have formed too small an image to cover 8x10.
This is Ross' development of the Zeiss series VII, of which Ross had earlier been a licencee - and which was often sold as a single (rear mounted) lens.
If the lens cell was part of a set, it went missing when this Ross was installed on the 8x10.

The single lens, unlike some others, is a very well corrected for this use - but F.11 is a bit dark for focussing.

[David Brunell]

Excellent, now I understand. Thank you.

[David Brunell]

A litte more information marked on the barrel:

F
5.9 to 45 (in increments)
7 3/4 inch
C
F 11 to 64 (in increments)
14 1/2 inch
S
F 11 to 64 (in increments)

And the barrel is marked Ross Combinable. So is it in fact a Combinable but now I am a bit confused about the actual aperture?

[Steven Tribe]

This confirms it was sold with both front and rear cell.

The F scale starting at F5.9 is the right one for the use of both cells at the same time.
The F scale starting at F11 is the right one to use when using just a single lens mounted.
I'll look up the coverage of the 7 3/4" Ross combinablen - probably full plate. This is not a common lens.
It doesn't give the full range, but says "that when the front and rear lenses are the same" the combined speed is always f5.5".
As yours is F5.9, the front and rear lenses must have been different in focal lengths.
Ross sold this as late as the 30's and it was popular on more expensive field cameras.

[David Brunell]

Great, thanks so much for the help Steven it is very much appreciated.