I think that your problem was that you were most likely using the built-in flash. There are a lot of threads here about AUTO-ISO and the built-in flash. It is generally agreed that you should either turn off AUTO-ISO when your are using it or limit the maximum to say ISO 800. Try using AUTO-ISO with higher settings but make sure that the flash is not going to activate, and I'm sure that you will like the results. Try using P mode instead of AUTO.