Canon 518 Single -8 - Manual (Page 17)

Focusing
Adjust the focus by turning the focusing ring so
that the subject can be seen most cleariy through
the prism screen rangefinder built into the center
of the viewfinder.
The aligned image can be seen more accurately
and easily the longer the focal length of the lens.
Therefore, first focus at maximum magnification
(telephoto) and then return to the desired mag­
nification.
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