I am new to photography and use a Nikon D3200 to shoot jewelry in a light tent. I use the original 18-55mm f/3.5-5.6 lens with Xit XTETN Auto Focus Macro Extension Tube for macro shots.
I have this problem where I would be shooting perfect images under a certain setting, then all of a sudden the light drops even though nothing changed (none of the light, settings, objects changed). See below two pictures taken a few seconds apart; and I took a third picture with a slower shutter speed but the picture came out even darker. This happened to me a few times already and I can't figure out why. Any advice?
I do not use the flash. All the light comes from the LED light stripes within the light tent.
LED lights flicker. Your shot-to-shot inconsistency has nothing to do with your camera. It is about the variability of the lights.
Assuming your camera is solidly mounted on a stable tripod, the best way to deal with it is to increase the exposure time (reduce the shutter "speed") until the flicker is no longer evident. I'd start at ISO 100 and 1/50 second and go from there.
I ended up taking off the extension tube, or replacing the previous extension tube with another one with a longer lens, viola, problem resolved! I can only assume the problem lies with the extension tube. Go figure...