7.11 Other Issues

Although many birders (including myself) consider flash to be nearly essential for serious bird photography, there are a few potential drawbacks (in addition to those outlined previously in this chapter) that you should be aware of.  However, rather than allowing these to dissuade you from taking up the use of flash (if you haven’t done so already), these should instead be borne in mind when shooting in the field, hopefully sparing you from making some common mistakes (or at least allowing you to recognize them earlier).
    First, and most obviously, flash can create shadows.  In most cases, this isn’t a problem, since the shadows will be formed behind the bird and won’t be visible to your camera’s imaging sensor.  Sometimes they can be visible, however.  Since the flash isn’t perfectly co-linear with the camera
s imaging sensor (i.e., since it’s generally positioned at least a few inches above the camera), any twigs or leaves that partially obscure the bird can result in ugly shadows on the subject—even if the offending foliage is rendered completely out-of-focus by a shallow depth-of-field.

Fig. 7.11.1 : Because the flash isn't perfectly co-linear with your imaging sensor,
it can create shadows visible in the image.  These are especially noticeable when
they are caused by twigs and such that happen to be in front of the bird, even
if they're rendered out-of-focus by a shallow depth-of-field.
(1/320 sec, f/8, ISO 800, TTL flash at +0 FEC, 800mm)

    In the image above, the branch passing above the bird’s eye causes a shadow to be formed on the eye itself, and on the eye ridge and the cheek.  In this case the shadow wasn’t terribly noticeable or damaging to the aesthetics of the image, but in many cases it can be.  Shadows like these can sometimes be removed later in postprocess, though doing so can be laborious. 
    Another, sometimes more subtle effect is what I call feather glare.  In the warbler photo below, you can see that the use of flash has resulted in many vibrant colors as well as many fine details showing up in the microstructure of the bird’s feathers (what are called the rachis and barb elements of the individual feathers).  Ignoring the blown highlights in the throat and white neck band, if you look closely you’ll also see that there’s a lot of white being reflected from parts of the bird’s plumate which presumably aren’t white.  This is most noticeable in the primary and secondary flight feathers on the bird’s wing, in this particular photo.

Fig. 7.11.2 : Feather glare is just one more thing to watch out for when using flash
for bird photography.  Though the primary flight feathers of this bird should ideally
appear dark gray with white edging, feather glare has reduced the contrast in that
region of the bird's plumage.  Diagnosing feather glare in the field takes some
experience.  Feather glare is very difficult to fix in postprocess, so it needs to
be avoided in the field when possible, by reducing flash intensity.
(1/200 sec, f/11, ISO 250, TTL flash at -1 FEC, 400mm)

In this case I’ve simply used too much flash, resulting in an unpleasant glare from highly reflective portions of the bird’s plumage (as well as over-exposure of some of the white feathers).  This is very difficult to notice in the field, based on quick peeks at the LCD on the back of your camera.  In addition, the ETTR protocol (section 6.2) would naturally lead you to continue increasing exposure until your highlight alerts are activated.  Some degree of feather glare may simply be an unavoidable cost of maximum-exposure approaches (such as ETTR) to flash photography of birds.  Occasionally checking your images by zooming via the back LCD may alert you to any feather glare that may be occurring at your current flash power level; in some cases you may be able to mitigate the glare without losing detail by reducing flash power just a bit.  Note that glare can be very difficult to remove in postprocess, so avoiding it in the field is to be desired, when it can be done without sacrificing other exposure objectives.
    As with all photographic (or merely observational) activities, a prime concern should always be the effect your activities are having on the bird.  Just as many people find bright flashes of light to be unpleasant, even disorienting, some birds may not appreciate excessive doses of photons from your flash unit.  In my experience, the amount of flash required for proper exposures of birds at typical distances in the wild is often enough to startle the bird, and possibly scare it away, though typically after the first two or three shots the bird will become accustomed to the flashes and continue foraging without taking any further notice.  I’ve seen birds ignore crowds of photographers frantically firing their flash units at it like paparazzi hounding Paris Hilton.  Some birds are flashed so many times by a crowd that occasionally two flash units will just happen to go off at exactly the same time, resulting in accidental over-exposure for both photographers.  The birds don’t seem to care.
    The only bird I’ve encountered that seemed to be noticeably upset about my flashing it was a juvenile osprey, who vocally scolded me after every flash, but did not fly (I stopped using the flash when it became apparent that the bird was overly sensitive to it).  In contrast, I’ve been told by raptor rehabilitators that it’s fine to use flash to photograph their captive raptors, since the flash doesn’t bother them. 
    Occasionally you may encounter a bystander who objects to your use of flash, on the grounds that you’re
harrassing the birds.  In these cases, even if you believe that you’re not causing the bird any discomfort (and even if the bystander doesn’t appear to have a firearm or other apparent means of unduly inconveniencing you), it’s often best to just move along or wait for the offending individual to wander off.  In most cases it’s simply not worth the stress involved in confronting a poorly-informed vigilante.  Bird photography should, after all, be a source of enjoyment, not stress.