Ross lens with revolving aperture

[nehartmannn]

Can anyone help....
I got my hands on a Gandolfi 1/2 plate camera (Gandolfi Makers London)
with a ROSS lens with a revolving aperture.
On the lens is the followings:

ROSS,London 8x5,O.A,DOUBLET 17338 (3 lines)

How old (new) is this lens

thans

niels-erik

[Gene McCluney]

That lens is 19th century, most probably. The rotating aperture wheel was generally used on some types of lenses in the 1880's. or thereabouts. It could be newer, but by the 20th century most camera lenses had iris type diaphrams. Some process lenses still hat waterhouse stops, though, but that Ross is a camera lens, I think.

[Ole Tjugen]

In Britain the situation was a little different to the rest of the world, since J. Lancaster held the patent for the iris aperture for quite a while. many other lens makers preferred to use wheel stops even well into the 20th century.

Apart from that little snippet, I know nothing about your lens - at the moment. :)

[Ernest Purdum]

For what it's worth, revolving stops are most often associated with the early wide angle lenses. They were so slow at f16 or so that only a few stops were needed. With other lens types, you got Waterhouse stops providing a wider range of selections.

[Scott Davis]

The 8x5 size indicator on the lens makes it sound like it was a wide-angle intended for use on a tailboard-style 8x5 landscape camera (non-rotating horizontal configuration). I've seen these with both wet-plate and dry plate holders, so they span from the mid 19th to very early 20th centuries. I'm not sure on the time frame for the popularity of the 5x8 format, but it died off earlier than others it seems, so most likely it would be confined to the 19th century for dates of manufacture.