I am a newbie photographer and had a question that has been plaguing me for some time now.
My NIKON D3100 camera's brightness meter (the lines that change on manual mode when one adjusts shutter speed) is clearly not working correctly. The reason I say this is because whenever I take a normal photo (manual mode) using 400 IS0 and 5.6 F-STOP, my shutter speed must be 1/10 to attain "normal" brightness, or brightness in the middle of the lines. This is unusual because 2 months ago, I was using manual mode, and taking photos at 400 ISO, 5.6 F-STOP, and 1/640 shutter speed; the brightness meter displayed "normal" brightness. Can someone provide insight into what has occurred, please? All my photos now turn out dark and I really just want to shoot like I was 2 months ago!
Help is appreciated, thanks! UPDATE: SPOT METERING IS OFF, MATRIX METERING IS ON. ALSO, ISO IS AT 400 AND IS NOT SET TO AUTO ISO.