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6.6 Drive Modes
The drive mode of a DLSR refers
to how many photos the camera will take when you press the
shutter-release button and hold it all the way down. In single-frame drive mode, the camera
will take only one photo, even if you
continue to hold down the shutter-release. In order to take
another photo you have to release the button at least halfway. In
continuous drive
mode, the
camera will continue to take additional photos for as long as you hold
down the button—just like with a machine gun that continues to fire
for as long as you keep the trigger squeezed. In fact, the use of
continuous drive mode is often referred to as “spray and pray”, whereas
the use of single-frame mode is often referred to as “sniping”, in
obvious reference to alternate methods of trying to hit a target with a
machine gun or a rifle.
Fig. 6.6.1 :
Spray-and-pray capture of an eagle in flight, via continuous drive mode.
By capturing the bird in many different poses, you increase the chances
that one
of the poses will be the one you seek. Note, however, that many
of these poses are
very similar—this bird’s wingbeat frequency happened to be a multiple
of the drive
speed (10 frames per second), resulting in many near-identical
poses. Note also
that these photos were all (unintentionally) overexposed—manual changes
to
exposure parameters during continuous drive bursts are, of course,
impractical.
Spray-and-pray
shooting (via continuous drive mode)
is best for birds in flight, where it can help you to get more shots of
the bird in alternate poses (e.g., wings up or down, head turned toward
or away from the camera, etc.). As mentioned in section 2.7,
however,
many cameras are limited in their ability to sustain continuous
shooting for long runs of shots. Obviously, if you keep the
button pressed indefinitely, you’ll eventually fill up your memory card
and then the camera will be forced to stop shooting. However,
when shooting RAW images (rather than JPEG), you’re much more likely to
fill up the camera’s temporary buffer before you fill up your memory
card. As mentioned previously, some cameras have much larger
buffers than others. Another issue with spray-and-pray is that
(except in live view mode)
the autofocus circuitry is temporarily
blinded every time the SLR mirror flips up during exposure, so that for
rapid continuous shooting the AF system may have difficulty tracking
the bird, possibly resulting in one or more out-of-focus (OOF) images
in the series. Obviously, for spray-and-pray you’d normally be
using servo AF mode rather than one-shot AF.
Although “sniping” (the use of single-frame drive
mode)
is generally associated with stationary subjects, it can also be used
for birds in flight, when coupled with servo AF mode. Whereas
spray-and-pray relies on random luck in getting at least one good shot
of a bird during its flight, sniping gives you more control, because
you dictate precisely when the camera will take the shot(s). If
your hand-eye coordination is very good and the bird is large and
relatively slow, you may be able to precisely time your shots so as to
get the bird at its best poses during the flight—such as every time
the bird’s wings are raised, etc. Another advantage of sniping is
that you can wait to press the shutter release until you have visual
confirmation (through the viewfinder) that the bird is in focus.
If your camera’s AF is a bit sluggish, you may find that the bird goes
in and out of focus slightly during its flight, as the AF system
struggles to track the bird. With sniping you at least have a
chance to try synchronizing your exposures with the times that the
camera has the bird in focus.
As we’ll see in section 6.9,
there are some special
uses for continuous drive mode that you’ll probably use only very
rarely for most types of bird photography: exposure bracketing, and HDR.
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