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.
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.