View Full Version : Flange focal length calculation

Thierry Schreiner
2-Jan-2008, 14:47

First of all, a Happy New Year to all of you LF guys out there.

My question is basically very simple, but as so often, I don't know the answer.

How do I calculate the flange focal length of a lens for a given distance?

Example: At infinity, the G-Claron 355mm f9 has a Flange Focal Distance (distance from back of the shutter to film plane) of 350mm.

Is there a formula to calculate the FFD for the lens if focusing distance is set at 10 metres, 5 metres, etc.

Thank you in advance for your answers.

Best regards from France


Dan Fromm
2-Jan-2008, 14:59


Two presentations of the same ideas.

Thierry Schreiner
2-Jan-2008, 17:34

Great. A 1000 thanks. This really helps me.

Best regards from the old continent.