Which camera do you use?? I have the Canon 30D & noticed that minor detail. The amount of shots changes depending on how much information is captured. When you use ISO 1600 it (the sensor) is bringing in more light (and noise) thus more image info. You can shoot outdoors at ISO 100 and get less shots than indoors at ISO 800. Best to just check the image size after its captured and guess how many shots you have left. If I don't make sense, just check my avatar :tongue1:

Question the question. Answer the question. Question the answer...

I wish I knew what I was gonna say :oP