Canon DS-8 - Manual (Page 24)

Viewfinder
Since the viewfinder of DS-8 is of the single-lens reflex type, the
exact picture image to be filmed can be seen without any parallax.
This enables you to compose the scene within the maximum field-
of-view.
■ Be sure the eyepiece shutter switch is set at “O”,
Zooming
When you wish to zoom or want to compose the picture properly in
the viewfinder, turn the zoom lens by using the zooming lever. The
image seen through the viewfinder will change in magnification and
the field-of-view will also change. When zooming is performed during
shooting, any desired zooming effect can be reproduced on the film.
■ The viewfinder magnification is in life-size when the focal length
is at 12mm.