Derogy lens

[Jannto]

Oh dear, thanks for answering. almost couple of years ago. If you are still around i could send a sketch of the lens...

[Steven Tribe]

Welcome back!

I have looked very carefully through the Derogy data. It has, I think, "Brevette" (Patent) engraved? The serial number suggests a variety of the foyers multiples. These were sold (usually) with a -ve and +ve central lenses, but I have one with 4!
The wheel stop is a puzzle! Could this be an adaption for stereo lenses to have exactly balanced exposures left and right.
The lens size is close to the 1st series, no.1 which is 44mm and a focal length of 11cm (without the central lens mounted).

[Jannto]

Welcome back!

I have looked very carefully through the Derogy data. It has, I think, "Brevette" (Patent) engraved? The serial number suggests a variety of the foyers multiples. These were sold (usually) with a -ve and +ve central lenses, but I have one with 4!
The wheel stop is a puzzle! Could this be an adaption for stereo lenses to have exactly balanced exposures left and right.
The lens size is close to the 1st series, no.1 which is 44mm and a focal length of 11cm (without the central lens mounted).

Yes, its Brevete. But I would be surprised if this is planned to be stereo as it weighs 1.3 kg. Can I ask you where you get the information about Derogy lenses. I have not found anything.

[Steven Tribe]

The Foyers Multiples Derogys are quite heavy - with more brass than usual!

I don't know of any other Derogy Petzvals that are in a plain barrel like this. Or any Petzvals that have wheel stops. Wheel stops are only possible (that is, sensible!) when the largest hole can much smaller than the barrel and/or lens.

The source of knowledge about Derogy is the Le Reve edition french booklet on French early phptography no.16. I didn't have this booklet handy in the early days of this thread.