Canon FTb Instructions Manual page 40

Fixing Mirror Upwards
In performing photomicrography, the Canon FTb can be
operated with the mirror locked in an upward position after
the picture has been composed in the viewfinder, in order to
eliminate mirror vibration.
To lock the mirror in an upward position, push down the
stopped -down lever and the lever lock to "M " .
The aperture is now stopped·down and controlled manually.
The mirror can be locked independently from film advance
and shutter speed operations.
When the mirror is locked in an upward position, SLR view·
ing is not possible, and distance must be estimated by eye.
When the mirror is locked, always keep the lens covered .
The film will sometimes become foggy if the lens cap is not
attached .
• After the mirror lock device has been used, be sure to
return the mirror lock lever to its original position. Failure
to do this will result in inaccurate focusing .
• When Canon Lens FL 19mm F 3 .5 is used, the mirror
should be fixed, and combined usage of the exclusive view-
finder to this lens becomes necessary .
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