Focusing; Range Viewfinder - Canon 7 How To Use Manual

Focusing

The lens has a "stopper" at the infinity position. Release the lens by
pressing the stopper and rotating the lens barrel. The lens will move
back and forth by rotating the lens barrel, which is coupled to the
rangefinder, enabling you to focus. Canon telephoto lenses do not have
a stopper.

Range Viewfinder

When you look through the range-view-finder eyepiece and rotate the
lens barrel, you will see two images either coincide or remain apart
within the comparatively bright circle in the center. When they coincide,
your lens is in focus.
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