Camera modification (re: infrared)

Shinnentai · Jan 31, 2005

I've been reading up on infrared photography recently. I understand that a textured backplate can result in the texture becoming part of the image due to the lack of anti-halation layer on the film. My SLR (Minolta XG-M) has a grid of tiny dimples (as opposed to bumps) on the backplate, but otherwise seems to meet the basic requirements for NIR photography.

I'm wondering if it's possible to modify the backplate. Examining the camera, the backplate is spring mounted, and presses against a set of metal pads on the shutter housing when the camera is closed, so "skinning" the backplate with a thin, smooth, opaque material seems feasable, on the surface at least. It wouldn't alter the film plane, since the plate pinions the film against the shutter housing, and the spring mounting seems like it would easaly accommidate an extra 1/4mm of thickness.

Any thoughts?

ksmattfish · Jan 31, 2005

I'd shoot a roll and see if you have a problem first.

Never mess with a film pressure plate unless you are positive you know what you are doing. Knock it out of whack, and you could be in for all sorts of troubles.

An extra .25mm may also mess with your plane of focus with your lenses wide open. At f/8 it would look fine, but at f/2 .25mm could move the film out of the plane of focus.

terri · Jan 31, 2005

I use a Pentax ME for my IR, and it does have that problem. However, it has only spoiled a few shots. I've learned to work around it, because I have shot enough to know that the faint pattern is only visible if I happen to be shooting into a large blank area that will develop into a certain tonality. ie, if it develops light enough it will not be seen at all, nor if it develops dark enough. And I never notice it when the image is busy, with lots of tonal ranges. I try to avoid things like stark cloudless skies (which is boring for IR anyway) and for the most part, it's not an issue. Just one more thing to be aware of, really.

You might notice the same thing, so do as Matt suggests here and run a roll or two, in various situations. If it's a problem in each and every frame, then you might want to experiment with that platen. And if you have success with it, come tell me about it!! :lol: