Certified Master Photographer Member of Professional Photographers of America
At the time I decided to go as full time PRO, an aspiring photographer had to demonstrate extensive knowledge of styles in architecture and art, also in the history of photography, as well as present his/her own photographs in the following groups.
Product Photography (at least 12 different groups of products from furniture to right down to earrings)
Studio lighting set up - at least six of them
Special darkroom developing techniques and use of different types of material
Darkroom chemicals depending on the requirements.
Once you passed all the exams to the above, as well as one year of apprenticeship, you could get the title of ‘Master in Photography’. You could apply for a license to become a professional photographer in your own right, and open your own studio.
We may also add that at the time I was shooting with film camera you couldn't simply check on camera display how the shot turned out (like in now days digital cameras). I had to know exactly how the shot will come out, since film developing process was time consuming and materials cost money. I jumped to digital in October 2001.