How should I credit images?

to my knowledge the owner- in general *salutes*- of a picture is the always the photographer. that being said in most cases i think they give the right to the company so "20th century fox" is okay as a credit.
if youre unsure who produces/owns the right to the tv show you can always check imdb.com (same for movies)since i think for movie stills they always give the rights to the studio as well.

if you get images from another website its usually a tad more difficult to credit unless they actually post a credit. if you have no idea who has the rights to the image you can put "unknown" and put the source in the description- so if anyone claims copyright or KNOWS the credit you can add that. i dont think anyone will pursue legal charges if you screencap yourself and credit the studio. for fanart you can credit the studio/owner and put the "artist" and source (e.g.creative changes by johnsmith456 fanpop.com)in the description. i dont think that there is need to credit the website (who does the same you do: take images who belong to someone else and post them..possibly though with written permission :P) unless like i said if you just add them as a source.