How do you take double exposures on a manual camera?

Answer 1

Most cameras do not allow double exposures. If yours doesn't (check the Owner's Manual to make sure) you can try this.

Depress and hold the film rewind button. Keep pressure on the rewind knob so it can't turn. Slowly advance the film advance lever to set the shutter. This does not guarantee perfect registration.

To make the necessary exposure compensations, use the camera's EV dial if it has one. For double exposures use -1; for 3 exposures use -1 1/2; for 4 exposures use -2. If you don't have the EV function simply multiply the ISO you're using by the number of exposures you want to make. Don't forget to set the ISO back to its normal setting when you finish.

Answer 2

Each camera can do this differently.

My Pentax K1000 (film camera from 30+ years ago):
1) take your first shot one stop unerexposed
2) on the bottom press the film release button (thats not the button that opens the back of the camera)
3) hold the film rewind spindle to keep the film from advancing
4) rotate the film advance lever (which just sets the shutter since you did 2 &3)
5) take the second shot one stop underexposed
and your done

Canon Rebel Xs
1) hold the two thumb buttons on the rear of the camera marked (*) and (AV +/-)
2) while holding those two buttons roll the selector wheel just behind the shutter release to select how many exposures you want to do
3) take your shots

Again all cameras do it differently, these are the two I have.