Scanning Glass Slides
 

Anyone scan large-format negatives or glass slides using a Canoscan?

Is it even possible? (I couldn't figure it out).

You need a fully light sourced top in order to scan larger negs. I could be wrong but I think the Canoscan and other similar scanners only have a light source on a plane just wide enough to do smaller slides and negs..

I use an Epson Perfection V700 scanner for larger negs, up to about 8x10.

Dave is correct. Most consumer-level scanners with "negative scanning capability" will only do 35mm or maybe as large as 2.5" wide, with the limitation being the light source which is typically a narrow opaque window running the length of the lid. The only flatbeds I've found that will do larger (without getting into more expensive professional models) are the Epson V700 and Epson 4990 (of which I have the latter). Both will do up to 8"x10" negatives and transparencies.

You can try to rig your own light source to do it with other scanners, but I don't think you will be too pleased with the results. I did a lot of experimenting when I started to pick up negatives here and there, and finally broke down and just bought yet another scanner (that made 3) which I use exclusively for transparent media. I was able to get a good enough image for identification purposes with a strong light source and opaque filter media (fancy name for computer paper) between it and the negatives, but for presentation or archival purposes, it was a pretty low-quality image.