wrote:
What are the rules if I want to take and sell photos from an amateur
built experimental airplane? I wouldn't be carrying anyone, just
taking pictures or videos and selling them. Do I need a commercial?

In general for the situation you described, no commercial ticket is
required. [Although taking the pictures yourself while flying is not
especially recommended.] I believe it is one of the things
specifically listed as examples of not requiring a commercial ticket.
The flying is considered incidental to the business (photography).
There is even a specific case sited - guy flies up and down the
lakefront taking pictures, then goes door to door selling them to the
respective homeowners.

Note that this would be different if you went to work for a photography
company who advertised for a pilot and was paying you specifically to
fly the plane in order to get photographs. In that case flying WOULD
be YOUR business, and a commercial license would be required.