View Full Version : Goerz Dogmar 210 mm Convertable???

26-Feb-2009, 10:36
I have a Goerz Dogmar 8 1/4 lens in a universal shutter, if I take the front element off and only shoot with the back element, would this double the focal Length??

Any thoughts would be helpful

Thanks John

26-Feb-2009, 11:33
Just found the answer to my own question from a 1930 magazine called the camera. I'm posting this for another forum member, were working on a trade.
" Consists of two pairs of un-cemented lenses. The two single combinations, which can be used separately at the smaller stops, are of different size, offering the advantage of three focal lengths in on lens" July 1930 the camera Adv.23

Gene McCluney
26-Feb-2009, 17:38
This is called a "convertable" lens. Using either front or back group separately will result in less quality (sharpness), in general.

Chauncey Walden
26-Feb-2009, 18:43
On mine, the back element is about 1.5x the combined and the front, about 1.9x. The single elements are quite soft wide open. I haven't developed the film yet to see just how soft. It appears very sharp at the combined length.