Canon FT QL - Depth-of-Field Scale

Depth-of-Field Scale
The depth-of-field scale indicates the range of subjects
which will be in focus sharply on the film. This range
will vary with the following factors: The depth-of-field
will be deeper the smaller the aperture opening, the
further the distance of the subject, and/or the shorter
the lens focal length. The depth-of-field will be shallower
the larger the aperture opening, the nearer the distance
of the subject, and/or the longer the lens focal length.
For example, if the lens used is 50mm and the subject
has been focused at a distance of 3m (10'), with an f/8
aperture value read off from both indexes on either side
of the indicator (orange line), the depth-of-field is from
approximately 2.3m (S') to 4.3m (14').
If the aperture is closed down to f/16, the picture will be¬
come sharp between 1.9m (6') to 7.6m (25') from the
camera. This range will vary with the f/stop selected.
50mm Lens f/8
Depth-of-field 2.3-4.3m (8'-14')
Focused at 3m (10')