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H4D
Note though that in this mode the lens will focus at a distance and will remain focused
at that distance while pressure remains on the shutter release button. In this way, you
can focus on a nearby object for example, temporarily positioned within the focusing
zone on the viewing screen and then without releasing pressure on the shutter release
button, recompose knowing that the focus remains on the object chosen even though
it is now outside the focusing zone. Releasing the pressure on the shutter release button
and pressing again half way would now change the focus setting to the distance of the
object within the focusing zone.
See Manual override in autofocus mode
for a useful way of working with manual
and autofocus settings in a combined manner.
Continuous
At Continuous setting (AF C), the shutter can be released rapidly before the lens is
focused in order to capture a split-second shot (in Single Shot, a capture cannot be made
until the camera has had time to focus). However, the camera will continue to focus if a
moving subject is within the focusing zone or if you recompose, even though the shutter
release button is half pressed.
One method to exploit this feature when photographing in a rapidly changing situa-
tion such as photojournalism, for example, is to keep the shutter release button pressed
down. In this way the lens focuses constantly (according to the focusing zone) and by
momentarily releasing the pressure on the shutter release and then immediately press-
ing again, you minimize the amount of time needed for the lens to check focus, thus
ensuring a split-second shot at optimum focus.
True Focus
The True Focus setting (AF T) is generally used in specic circumstances to automatically
correct for camera angle/focus setting discrepancies but it can also be combined with
other autofcus settings.
To be able to exploit True Focus correctly, a few important points should be studied in
order to obtain a full understanding of how and when to use it. Basically, there are four
variables to pay attention to listed below: (a) proximity of camera to subject, (b) focal
length of lens, (c) aperture setting and (d) movement of camera and/or subject after
setting. The closer you remain to the ideal situation with regard to these variables, the
more noticeable the eect of True Focus will be.
a. The closer you are to the subject, the worse the original problem becomes. Conse-
quently, the need for True Focus solution becomes greater and its application thereby
becomes more noticeable.
b. Short focal length (wide-angle) lenses naturally decrease camera to subject distances
and therefore, following the point in (a), produce a greater need for True Focus adjust-
ments.
c. Smaller apertures increase the depth of eld and therefore would lessen the need for
a True Focus solution. However, smaller apertures produce a dierent visual eect, so
True Focus therefore allows the exploitation of shallow depth of eld without the fear
of unwanted focus restrictions.
d. The mechanics of True Focus use, amongst other things, camera to subject distances
to calculate the required amount of adjustment. It therefore follows that if the camera
or the subject move after the initial setting has been made, the calculations will not
be applicable anymore. So, to ensure the optimum correction, both the photographer
and the subject should restrict movement as much as possible. Please note that with
some lenses (particularly longer length lenses) just a few centimeters movement can
essentially ruin the result.