Aperture priority

Many people use aperture priority without thinking about the consequences.  By this I mean that you have to pay attention to what the shutter speed is doing.  It's very easy to get so involved in choosing the amount of depth of field you need -- as I did in this shot of wild hyacinth macaws in Brazil -- that you forget about the shutter.  In this shot, I needed both birds to be sharp.  Since I was using a 500mm lens, that meant that the lens aperture had to be at least f/11.  At the same time, the shutter had to be fast enough to get a sharp picture.  Therefore, I raised the ISO to 1000, plus switched on the image stabilization, to boost the shutter speed to 1/200.  I would have liked a faster shutter, but I figured the image stabilization would compensate for the movement of the lens.  Since the birds weren't moving, this worked out well.