I'm trying to find a flash for my Pentax K100D.....my dad was into Photography awhile back and he's got a couple flashes that he used to use on his film camera....he's got 2 Vivitars...one is a Vivitar Electronic Flash 1900 and the other is a Vivitar Auto Thyristor 283 (they're older) - he has no manuals or guides with them any longer and I'm wondering if I can use either of them with my DSLR? I know voltage is a big deal (I don't want to fry my camera! ) - I am shooting a wedding in a couple weeks and I finally was able to go the church today and I DEFINITELY need another flash for my camera! (rather than the on-camera flash) If those flashes are no good, can anyone recommend a good, cheap flash...just something to get me by for a while? Thanks so much!!!