Linhof M679CS DOF Calculator Dial for 36 x 48mm

The Linhof M679CS DOF Calculator Dial for 36 x 48mm is an optional DOF / depth of field calculator dial for the M679CS camera. It connects to the camera's focusing mechanism and is used to exactly determine depth of field for 36 x 48mm formats. The interchangeable dial, which is part of the depth-of-field optimizer of the camera's optical bench, is calibrated with apertures. Push the dial into the holder on the left side of the camera as you look at it from the rear. As you focus on your near point and then zero the knob and focus on your far point, the calculator will tell you what aperture you need in order to achieve that depth of field. Then, you simply back off to half the distance between those near and far points. The aperture you need changes with the magnification ratio.