Flange distance Biogon 4.5/75

[cpd]

Hi,

Do you know the flange distance of the Biogon 4.5/75 at infinity ?

Many thanks.

[Ian Greenhalgh]

It's around 39mm.

[Dan Fromm]

It's around 39mm.

Interesting if true.

My USAF data sheets give the Goerz-made 3"/4.5 Biogon's back focal distance as 1.5 inches. This is the distance from the rear element's vertex to the film at infinity.

My data sheets don't give a flange focal distance for the 3"/4.5 Biogon, state that the 1.5"/4.5 Zeiss Biogon's ffd is ~ 3.4 ". The big un's ffd should be roughly twice that.

[Jac@stafford.net]

Interesting if true.

My USAF data sheets give the Goerz-made 3"/4.5 Biogon's back focal distance as 1.5 inches. This is the distance from the rear element's vertex to the film at infinity.

39mm is ~1.5"

[Dan Fromm]

Stafford, the OP asked for flange focal distance, not back focus.

[cpd]

Thank you!!!

CP