Quote "For making POV (persistence of vision) what kind of motor I need to use and what should be the minimum RPM of the motor is needed?"
I think you mean Time-Lapse photography where you shoot video as as multiple single frame shots for later lining up in a video editing software.
I'm using a 360 continuous servo pulling a timing belt attached to the camera carriage moving at the slowest the 360 servo could go. The slower the better/smoother the resolution when you line up all your individual time-lapse photos in adobe premiere to make a video (making each photo lasts for 0.02 or 0.01 seconds).
I'm able to start/stop the 360 servo and wait/hold position until the camera shoots (night sky shots need longer shutter exposures around 10 to 15 secs of exposure. Day shots shorter exposure). You can set the delay of movement in the arduino. The Spring RC hobby 360 servo i'm using gives me about 45rpm at the fastest and about 10rpm at the slowest.
I use another standard servo to mechanically click the shutter remote button which could be delayed within the remote to give the servos a chance to move then shoot when it stops. Shooting long exposures while moving will blur your images. That's your side to side movements.
For panning (and tilting) while sliding, you'd need an even slower motor (and this is where I'm at in my project. I have tried using another 360 servo for both pan and tilt movement but at the slowest setting the slowest speed is still too fast to make it work. Enter stepper motors where i can hope to make micro movements to center the image as the camera slides for longer usable shots where the subject won't get out of field of view.
At this point in my project i'm trying to get the stepper (cheap type bundled with arduino that runs on 5volts) to run in the same sketch as the 2 servos to make the arduino the master clock of the 3 motors. If i can get over this hump with the help of this forum then I would have the bare minimum working on this project. Any tips on this setup, you wizards of code.
Many thanks for this treasure trove of information.