Hey all, I just took the dive into film because it's awesome and manly. I need to buy a battery for my Mamiya and there's a load of generic batteries out there but I'm not sure which one is the best one in terms of holding its charge and reliability. Do any of you fellas have advice? The model of the battery: "The Mamiya M645 uses one 6V silver oxide battery 4SR44 (Eveready No 544, UCAR 544, Mallory PX28 or equivalent or alkaline battery 4LR442." - Owner's Manual Thanks!