Darlot wide angle lever's number

[mylek]

Hi,

i'll like to know which focal length for the Darlot hemispherical wide angle lens has the number 3,5 and 7 on its aperture lever. I'm also seeing some with 4,6 and 8 like a #3 5".

Regards!

[Bruce Schultz]

Somewhere I read those numbers indicate the increase of exposure for the smaller aperture. So if the exposure with the lens wide open were 2 seconds, the 3 would indicate the exposure would be 6 seconds.
But I could be wrong.

[Steven Tribe]

Best to start with CCHarrison's Darlot catalogue at
http://www.antiquecameras.net/1890lenscatalogue.html


THis gives diameter and focal lengths for the various sizes.

[mylek]

I read the same thing about the aperture but i'm wondering why some focal length has pair and other impair number.
Which focal length have 3,5 and 7 marked on them. I saw both on the web but most of the time there is no information about the focal length.