With a wide angle, in a recessed lensboard, adding a center filter restricts access to the lens controls. What happens if one puts the filter behind the lens? I have seen a thread that states center filters are always put on the front, but no explanation. If no one talks me out of trying, I will and report back.

-- James E Galvin (jegalvin@lbl.gov), December 06, 2000

Answers

Geeze, what the hell do we care whether you expose a sheet of film or not? Don't you think you'd learn more by doing that than just talking about it? If you think you've learned something, and want to report it, thanks for the info!

-- Alec (alecj@bellsouth.net), December 06, 2000.

Center filters are designed to be used a certain distance from the lens. Even putting another filter in between the lens and the center filter will mess up the results you get. Putting the center filter behind the lens will really throw off the results. The cone of light exiting the lens is much different than the cone of light entering it. Try it, but don't expect good results.

-- Michael Klayman (michael@schneideroptics.com), December 06, 2000.

Even if manufacturers made them for the rear, would you really want to focus giving up ~2 stops of illumination on the GG?

-- Larry Huppert (Larry.Huppert@mail.com), December 06, 2000.

FYI, an explanation of Larry's point: mounting a filter at the rear of the lens introduces a focus shift, and therefore it is necessary to focus with the filter in place.

-- Q.-Tuan Luong (qtl@ai.sri.com), December 07, 2000.