The quick definition of commercial is that you plan to sell the photo. You can be a professional photographer and shoot Antelope Canyon with no intention of selling the photographs.
For Lower Antelope, all you need to bring is a tripod and they will consider you a photographer. (You get an extra hour in the canyon for no additional cost.)
Here’s an excerpt from the Navajo Parks page
Requests for commercial filming and photography in areas under the authority of the Navajo Parks and Recreation Department are received regularly. The purpose of these Commercial Filming and Photography Policy and Procedures is to establish guidelines to be followed in the application for, review, approval/disapproval, of commercial filming and photography permits.
Navajo Parks and Recreation Department shall allow commercial filming and photography in tribal parks, recreation areas and monument only in a manner consistent with these policies and procedures.
Navajo Parks and Recreation Department, has the authority to issue filming permits in tribal park areas pursuant to Government Services Committee resolution GSCJY-18-04, Section IV. J.
These policies and procedures apply within tribal parks, recreation areas, monuments and other areas under the authority and supervision of the Navajo Parks and Recreation Department. The policy and procedures also apply specifically to filming and photography undertaken for commercial purposes, i.e. for financial gain or public display and exhibition.
- $50.00 Processing Fee for applications that have all the required information for one person. ($25.00 additional Processing Fee that involves photocopying for more than one person or requests for additional documentation or revisions)
- $100.00 Processing Fee for weddings, film companies or photography workshops that involve five or more people
- $200.00 Processing Fee for all “After-the-Fact” requests for Special Use Permits.
Here’s a copy of the photography permit application