which is better and for what reasons? 4 base or 16 base scan at toronto image works? 16 base is really pricey
Just refers to scanning resolution - low and high res. 4base will give you 3mbish files with 1024px as your shortest edge for 35mm and 16base will give you 2048px, 12mbish (if you get 16base, I would also ask for tiffs instead of jpegs)
All in all, 4base is good for web use and most things, 16base if you plan on printing large or editing heavily (I also prefer higher res for medium format work because you have all that detail so why cheap out)
I’ve also started to go to Downtown Camera for develop+scan because it’s cheaper and you get higher res base level scans.
Long way to answer, but hope that helps