I remember many moons ago when 2415 technical pan film was made. It was originally meant for microscopy, had very high resolution, incredibly fine grain, was photographically slow BUT unusually red sensitive. It also responded very well to gas hypering, and thus become a mainstay for monochrome amateur astro imaging. later, even the professionals started using it
http://en.wikipedia.org/wiki/Technical_Pan
The real amazing thing was tech pan film was as cheap as chips. When it first hit the market it wasnt available in large glass plates and so the professionals didnt use it but the amateurs could, and so for the first and only time in history, we had a BETTER imaging format than the professional astronomers. Sadly that isnt the case with electronic imaging.
To think if electronic imagers never happened, we could still do LRGB with techpan. Shoot a unfiltered luminance, then put in a focal reducer abd shoot through the filters, then use a high resolution film scanner to resize and combine them all.
A cheap 35mm SLR, and a roll of hypered techpan together a few hundred bucks total, could capture many megapixels