I need a scanner for mid-format negatives in which light is beamed from one side through the film and registered digitally on the opposite side. What is the terminology for such technology so that I can search for it. What I don't want is document scanner technology in which the light source and digital registration is on the same film side, with a white background reflecting the light on the opposite film side. Anyone?

It's called a transparency adapter/head. With canon scanners, just look for the letter "f" at the end of the scanners model number LiDe 8800f for example - which I own. Scans 35mm and 120/220 format. Been replaced by the LiDe9000f.

The Epson v500 though v750 are the same. At least I think the v500 can scan 120. I used to own an Epson 1250, which could scan everything upto 5x7 film/plates. Putting cling-film on the platen allowed me to make some very nice fruit slice scans.

Finally, there are some dedicated 120 film scanners. Unlike 35mm (where prices start at £100) these are really expensive - in excess of £2000. Unless you're a professional (or just rich) a flat-bed scanner is the best option.

Thanks greatly. That was exactly the information I needed. Sorry for the delayed response. This blog lost my username.