Canon EF - Manual (Page 49)

• At the ”B" setting, the shutter will remain open as
long as the shutter button is depressed. A cable
release is a handy device for holding the shutter
button in for long periods of time. Also, it allows the
shutter to be opened without the photographer
touching the camera or button directly, and there­
fore keeps camera shake to a minimum, thus insuring
a clear picture. At "B," the aperture ring must be set
manually.
• Intentional blur oftentimes can give your photo­
graphs a convincing feeling of action. Two types of
intentional blur are (1) subject blur and (2) back­
ground blur created by panning. Subject blur (1) is
created by keeping the camera still while the subject
moves across the field of view. The subject becomes
blurred while the background remains sharp. Back­
ground blur (2) can be created by panning, or
following the subject with the camera, keeping the
subject basically at the same position in the view­
finder. The subject remains relatively sharp while the
background blurs into a streaky effect. Experiment
by using slow shutter speeds of 1 — 1/60 sec. A
neutral density filter (ND4 or ND8) over the lens
will permit using slow shutter speeds even with fast
films.