[sane-devel] off-topic 25 mm scanner

[Ulrich Deiters]

Genuine slide scanners usually have - or should have - additional
features like focus control (you need that if you have framed slides).
I am not sure that such a feature is built into an add-on to a
flatbed scanner, unless it is a really expensive model.

I think the resolution of commercial fine-grain slide film is about
5000 dpi. There may be higher resolutions possible, but you have
to ask the CIA or the KGB about them. :-)
But these 5000 dpi can only be realized if you write on the film
with a specialized optical system. If you use a lens that is not
made of calcium fluoride, if you are not restricting yourself to
taking pictures at infinite distance, and if you are not using
monochromatic light, you are most likely down to 3000 dpi. If
you use a zoom lens, 2500 dpi is more likely.

My advice would be to look for a used slide scanner (Canon 2710F)
is OK, for instance). Or photograph your slides with a digital
camera!

Regards,

Ulrich Deiters