I am a newbie with a new SLR camera.
I wonder there is any calculation or rule of thumb to getting setting right.
Eg, if I shoot in ISO 100, how they relate to shutter speed, aperture, etc. I shot many times, I just rotate the knob just to hope everything is correct. How do I know e.g if I set Apreture in AV mode, what speed or Iso should I do to get a good shot.
Can a good light meter work all this out for me?