Depth-Of-Field Preview - Canon EF135mm F2L USM Instruction

The following applies to the EF 135 mm f/2L USM, EF 200 mm
f/2.8L II USM, and EF 400 mm f/5.6L USM lense:
Before switching the focusing range, turn the focusing ring to select a
•
focusing distance somewhere within the desired range.
If you do not set the lens to a focusing distance that is within the
•
selected focusing range, autofocusing may stop when it reaches the
range boundary. This is not a fault. If it happens, press the shutter
button halfway down again.
The following applies to the EF 200 mm f/2.8L II USM, EF 300
mm f/4L USM, and EF 400 mm f/5.6L USM lenses:
If the tripod mount covers the focusing limiter switch, it may be difficult
•
to operate the switch. In such a case, loosen the tripod mount's lock
nut and turn the camera so that the switch is clear.
ENG-5
5. Depth-of-Field
Preview
The depth of field is the zone of
acceptable focus in front of and
behind the point of optimum
focus.
EOS cameras equipped with
the depth-of-field preview
feature allow you to see this
zone of sharp focus in the
viewfinder. The depth-of-field
scale is an approximate guide.