I bought a Nikon FM2N today, and am having trouble working out how to use it. But just a few questions really - Loaded a roll of film - Kodak Portra 160NC. Now what do I do with the 'ASA/ISO' control on the top face of the camera? Would I be right in assuming that I keep it set to around 160 (or as close to as I can, using the unclear dial)? Or am I completely wrong? Or can I adjust the ISO according to the sensitivity I require? So many questions! I have experience using ISO settings on my Nikon D80. I think that's all that's confusing me right now. Thanks!