Are you using the camera thing correctly? Basically, the enemies spawn in waves. Do a team rotation ending in Eula burst which should wipe out all the enemies in that wave. Doesn't really matter too much how you do the rotations just keep Fischl's oz around, have Bennett burst to heal/give buff, Kaeya for energy battery, Eula for massive burst damage. Once you kill a wave you should have your camera charged. Wait for the next wave of enemies to spawn in the center and run a little bit aways from that so you can capture the entire group's weak spots in the camera shot. Use the camera to wipe them all out. If you need to charge the camera again do a rotation to wipe out a wave. If you keep using the camera to get ride of entire waves in one go you can rack up the points. I think I captured 99 weak spots in the 4th stage on my first try with like 4500 points.