Polaroid 636 Repair Manual page 26

15. There are three different conditions in which a flash picture can be taken:
1 - In high ambient light.
2 - In low ambient light with the subject near the camera.
3 - In low ambient light with the subject far from the camera.
16. Basically, the Model 636 uses either a light measurement alone to fire and shut down the
flash, or a combination of light measurement and time measurement to fire and shut down
the flash. The method used depends upon scene brightness.
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