Cone shpaed Macro Lensboards

[Robert J. Triffin]

Why do Luminar lenses require cone shaped lens boards? I saw a picture of such a cone shaped board in a Linhof book with a Luminar lens.

Robert

[Michael S. Briggs]

One reason is to make it easier to light the subject. With very short focal lengths for larger-than-life-images, the camera is so close to the subject that it can make lighting the subject without shadows from the camera difficult. That said, I haven't found a cone lensboard to be needed when using an 80 mm enlarging lens on a 4x5 camera--the lens already sticks far enough out of the shutter that lighting is reasonably easy. On some cameras, another reason might be to increase the distance from lens to film to allow greater magnification.

[Paul van der Hoof]

In addition to the comments above, a cone or other extension is often used in macro photography to give you more bellows extension and there for greater magnificaton.