For this achievement, and all other research ones for that matter, I recommend equipping an offensive plasmid, such as Inferno, and the camera. This way you don't have to switch to other weapons and back to the camera all the time, which is a tedious process.
Take multiple photos. You'll get a penalty for every additional picture of the same foe, but as long as the photo gets made, do it. After some time, it'll deny the photograph because the score is too low.
Film is cheap. Stock up and take pictures, restock and take more pictures. Don't forget some EVE as well, for aforementioned offensive plasmid. After a while, the achievement will pop.