I have a Nikon D 7100, and it was bought a year after it came out, with an original Nikon battery and a compatible reserve battery which goes in my battery grip on the bottom of my camera. My question is this. My shutter button when I press it down, seems to be very slow or shall I say I have to push it down further with my finger to trip the shutter. When I recharged the battery, it seemed fine for about 10 shots, and then it got slow again. Is this a battery problem, because they are old(older) or is this a camera problem. Thank You for any help in advance