It's German, made by Kiesewetter around 1933. There are several Photoscops, so details depend on which actual model you have. There's a square one with a rectangular cell on top; in fron there's a semi-circlue rule with shutter speeds and a pointer for film speed in Scheiner--that's the regular Photoscop. There's also a round Photoskop K that has a glass dome in the middle for the cell, and the numbers are all marked on the side. That's also around 1933. It's calibrated in Scheiner and DIN.
They're both unusual and hard to find in the USA. I don't know how much they're worth because I don't see them for sale often enough. Even if they do work, they're mostly just for curiosity value now. They're fun to play around with, but you probably wouldn't want to trust it for serious work.