I recently inherited my grandpa's old Argoflex camera. I must admit, I've never used a film camera before. I'm dying to know if I can relate what I've learned about the 'photographic triangle' to real film. Which brings me to my question, what ISO film to get? I found some Kodak 620 film at B&H and it seems to come in three speeds(?).. 100, 125 and 400. http://www.bhphotovideo.com/c/shop/336/Other_Film_Formats_110_127_620_828.html So if I wanted to take a portrait of my mom, with my daughter(to give to great-grandma!) I should get 100. right? Is there a big difference between 100 & 125? What is 400 for? The shutter seems fast enough for hand held use.. but certainly not fast enough for sports and what not, so why would you need 400?