Still here does mean 'unmoving' and it is a type of photography.
The unnamed photographer (who took this still photograph).
It may sound odd as, admittedly, all photographs are 'stills' but it is used in contexts where there could be confusion with film-makers. For example, in film credits, there are lots of photographical credits relating to the actual film. Then you'll also see a credit for 'still photography' or the 'still photographer' who is a person who takes normal photographs of the action, which can then be used for publicity shots etc.