Canon Model 7 - Manual (Page 27)

When you have finished a roii of film and you try to advance the film, you will feel
tension on your finger. You should then stop winding and remove the film from
the camera in this manner:
6 Pull out the rewind crank as far as it will go and take out the film cassette or
magazine.
Be sure to put the lens cap on before rewinding the film.
If the film is forcibly wound after all exposures have been completed, it will
be impossible to rewind the film. It will have to be taken out in a darkroom.
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