Quote Originally Posted by DWThomas View Post
In theory, narrowing the spectral bandwidth for B&W could improve the sharpness, can't say I've ever tried it. The light wavelength enters into the equation for pinhole optimization. . . .
Long ago I did some experimenting with films and filters from blue sensitive to IR, and found that it does make a slight difference. Fine-tuning pinholes and spectral response for optimum results makes insignificant improvement in almost all pinhole photography.