To get this achievement you have to research the following categories fully:
With seperate achievements:
- Thuggish Splicer (Melee weapons)
- Leadhead Splicer (Guns)
- Nitro Splicer (grenades/molotovs)
- Houdini Splicer (Teleporting ones)
- Spider Splicer (Hangs from the ceiling)
- Rosie (Guns)
- Bouncer (Drills)
- Little Sister
Without seperate achievements:
- Turret (both rocket and machine gun turrets count)
- Security Bots
- Security Cameras
If you want to maximize it as soon as possible, use the researchers eye tonic for extra progress from each photo. You'll get bonus points for having multiple subjects in the same photo. You can photograph dead enemies, and also the same enemy multiple times but this will reduce the progress drastically. To finish this off as soon as possible however, you should try to take at least 2 photos of each enemy with as high a rank as possible.