The film question has been answered rather satisfactorily I feel, but regarding the battery amswer, I somewhat disagree.
Why use a battery at all? The OM1 is a mechanical camera, and therefore is designed to work without a battery. Sure, the meter is rendered useless, unless modded as described above. But what about using a handheld meter? If you need an advanced one, then many are available, with more precise readings than normally available from an in-built camera meter. There are also mechanical meters, which don't need batteries at all. The king amongst these is the Sekonic L-398. It gives incident and reflected readings, but is more accurate than you would believe. Even though it can't do flash or spot readings, its still a fantastic meter. As a back-up meter, it can't be beaten. And for those that can do without spot and flash readings, then its a perfect main meter...IMO.
If you are not going to be using flash, save yourself £100 and use the PhotoMeter app for the iphone (I'm sure theres an android version if that's how you swing). It's spot on for readings and is free. But yes G is right, have a go shooting mechanical. It's liberating.
If you are not going to be using flash, save yourself £100 and use the PhotoMeter app for the iphone (I'm sure theres an android version if that's how you swing). It's spot on for readings and is free. But yes G is right, have a go shooting mechanical. It's liberating.