I had an FE2 out last weekend, to finish up the roll from earlier in the year. After a few shots, the mirror didn't come back after a shot, though I don't know if the shutter stayed open or closed. I turned the knob to M250, and the mirror returned. Seems that the battery has enough to open the shutter and mirror up, but not finish it. If I press the button to turn on the meter, it goes up to the right spot, and then immediately back down. So, the last few pictures on the roll taken with the M250 setting. I don't remember now which battery this is, maybe the one that came with it, or from another camera. I didn't buy a new one for it. Finished up the roll of Gold 100 (GA).