Minolta XG-A - Releasing the Shutter

36
Depth of field
The distance behind and in front of the
focused distance within which the image ap-
pears
acceptable sharp is called the depth of
field .
It
extends a greater di stance behind the
focused distance than in front and is deter-
mined
by three factors: the aperture size, the
distance at which the lens is focused, and the
focal length of the lens in use. Depth of field
~ ~ ~ ~ . i ~ ~ ~ - o
~~ ~ ••• t ~~ - o
~---+---'----'-..L.........L.. - O
~ Focused distance -1
increases as the lens is stopped down (e.g., f/2
to f/16) and becomes greater the farther from
the camera the lens is focused. It decreases as
the lens is opened up (e.g. f/16 to f/2) and the
closer to the camera the lens is focused. Depth
of field is greater for short fo'cal length lenses
than for telephotos at the same focused di s-
tance and apertu re o It is at its least for any
given lens
in normal mounting when the lens is
at maximum aperture (as when metering and
focusing normally with Minolta MD- or
Me-type lenses) and at minimum focusing
distance.
Depth-of-field scale
The near and far limits of acceptable sharp-
ness can be
determined from the depth-of-field
scale
on the lens barrel. With the lens focused at
a given point, the image will be in satisfactory
focus from
the nearer value 'to the farther value
on the distance scale indicated by the depth-of-
field scale marks for
the aperture to be used.
For example, if a 50mm lens is focused at