Flying is not "incidental" to the business of aerial photography. It
is, in fact, an integral part of it. I would say a Commercial
Certificate is required to be PIC on a hired photography flight.

If a Private Pilot is flying around taking pretty pictures, and then
selling them door-to-door or at art shows, I don't see how that would
require a Commercial Certificate.

If you asked 4 FSDOs, you'd get 4 different answers.

Lee Ross
N466SR
CP SEL IA
www.Rosspilot.com