To be big enough to read the image needs to be about 1.5-3MB per page. BUT each page of the microfiche image is NOT the size of a 35mm negative (864 Sq mm) but an area 10X14mm (140 Sq mm). Flatbed scanners are not the way to go, nor are film scanners up to the job either. The solution is to build your own camera. It's not as hard as you might think, mine works very well!