BarryS

23-Feb-2011, 08:30

I'm attempting to build a copy of the famous Dallmeyer-Bergheim soft focus lens and it would really help to have some measurements from an actual lens. Specifically, I'm interested in:

--The focal length and diameter of the positive plano-convex element (even if this info is all I can get, it would be helpful)

--The diameter of the rear plano-concave element

--The distance between the elements at the maximum focal length of the lens

--The distance between the elements at the minimum focal length of the lens

--The distance of the aperture from the front element

--Any estimates of coverage at the minimum and maximum focal lengths

Also, does anyone have the simple telephoto formula for how the distance between the elements affects the focal length of the lens? Thanks.

--The focal length and diameter of the positive plano-convex element (even if this info is all I can get, it would be helpful)

--The diameter of the rear plano-concave element

--The distance between the elements at the maximum focal length of the lens

--The distance between the elements at the minimum focal length of the lens

--The distance of the aperture from the front element

--Any estimates of coverage at the minimum and maximum focal lengths

Also, does anyone have the simple telephoto formula for how the distance between the elements affects the focal length of the lens? Thanks.