I've read a few things here and there and decided that setting my camera to P(rofessional Settings?) was the way to go.
This setting gives you preset Shutter Speed and F stops for whatever subject you put in your viewfinder, which you can adjust via the rear toggle wheel thingo (aperture more open, shutter faster and vice versa) to get 'the same' shot based on your ISO setting.
On the whole, it's worked alright, and I have been able to adjust the settings once the focus is locked to change the speeds or F stops to make difference shots of the same image.
However, every now and then I get a black frame, or a very small smudge of what I'm looking at in the frame, and that's even when I don't make any alterations, just put it into P, lock it and shoot.
Is it due to shooting form the shade through sunlight into shade again? Or is it something more practical with the settings that I've missed or messed up?
(note - when I say frame I mean the image taken, if this is the wrong terminology, please let me know).