A photographer on the field should be restricted to what is called a "media area". This area can be placed anywhere on the field and should be agreed upon and noted to the coaches prior to the game. Ideally, the media area should be chalked off, something like a coach's box.
A live pitched, thrown or batted ball touching anywhere within the media area, or touching anything within it (photographer, camera equipment, chair, etc.) immediately becomes a dead ball.
The base award is the same as any other play where a ball goes into a dead ball area. If it's a pitch, all runners are awarded one base. If it's a thrown or batted ball, all runners get two bases.