>I am using my new D800 and 70-200mmVR 2.8 lens with autofocus >to photograph hummingbirds. I am worried that the constant >refocusing as the little devils fly by will damage the lens >mechanism. Will this constant extremely rapid change with >autofocus degrade the lens. Are there any precautions? Thanks >so much for any advice.
if you are talking about very little refocusing, the behavior of your lens is normal. Your combo is just tracking the bird very quickly to be in perfect focus. You can change af-c to af-s and focus on a fix place and just wait after the bird.. if too long, you can focus manually and wait.. Fabien.