Bill,Originally Posted by nsurit
I usually use old Large Format shutters for my Pinhole cameras. The old Kodak slip-on, friction-fit Wratten filter holders (Series V, VI, or VII, depending on the old lens size) work quite well. I use the different filters such as the Aero Yellow, K2, Green & Red to change the contrast of B&W film- especially if I'm using out of date Polaroid (cheap!). I use a couple of the Color filters to warm up the usual bluish color shift, again especially with Polaroid.
You can tape a 55mm x 55mm plastic cut-to-size filters on the inside of the Zero Image, using black photo tape... I think that's what Zernike Au suggests on his site: