i notice a lot of people here use adaptors with (nikon) prime lenses. i know the benefits of primes are that they can achieve incredible dof and faster f-stops. now, my question is.. if one has enough available light, why don't shooters use the convenience of zoom lenses more often?

Justin.

For a given f-stop and focal length setting on the zoom, the same depth-of-field effect can be achieved.

Prime lenses are chosen also for there being fewer pieces of glass inside, therefore fewer glass-to-air surfaces which may reflect stray light which loses deep contrast. Fewer pieces of glass also mean in most cases a sharper image.

Some still-camera zooms may not hold focus through the zoom range.

Plus, many zoom lenses tend to breathe -- that is, they change focal length slightly when the operator changes focus, which isn't desirable. A prime lens won't do that, since by definition it can't change focal length.

Justin.

For a given f-stop and focal length setting on the zoom, the same depth-of-field effect can be achieved.

Prime lenses are chosen also for there being fewer pieces of glass inside, therefore fewer glass-to-air surfaces which may reflect stray light which loses deep contrast. Fewer pieces of glass also mean in most cases a sharper image.

Some still-camera zooms may not hold focus through the zoom range.

thanks bob! that totally makes sense. less glass = better pictures.