Cruise.Elroy: P.S. I'm not 100% sure but I think you can get all bipidri even late-game. There aren't any bipidri that "disappear" or become unavailable.

Cruise.Elroy: There is a small short-cut you can use if you want to find out if a picture "works":
*save your game
*go to your folder with the save-games
*go to the appropriate save-game and look around until you find your photograph data.

There should be an image and a .dat file for each photo in your camera: the .dat file contains a list of all "items" that your camera snapped. If it's empty, you know it didn't register. If it hits home, there should be at least a single entry for the bipidri.

kalirion: Do I need to keep the photos around until the end, or can I overwrite them once I've shown them to the guy?

Waltorious: I believe that once you've shown them to the guy you can delete the photos.