7.7 Freezing Hummingbirds

A perennial question from literally hordes of bird enthusiasts is how to “freeze” hummingbirds via stop-action photography.  The simple answer is that it doesn’t require a fast shutter speed, but rather a short flash duration in conjunction with a high flash ratio.  We’ll dissect this strategy in detail below.


    First, recall that shutter speeds on most cameras range up to about 1/8000 sec (even on pro cameras).  Flash durations, on the other hand, typically bottom out at 1/35000 sec, which is indeed much faster than the fastest shutter speeds.  Although hummingbirds only flap their wings about 50 to 200 times per second, the criterion of stopping the motion as seen by the imaging sensor’s photosites translates into required speeds in excess of 1/10000 sec.  Although today’s mechanical DSLR shutters still can’t satisfy that requirement, today’s flash durations can. 
    In order to use the flash’s pulse duration to “freeze” the image (as registered by the imaging sensor and judged by the human observer), the flash ratio needs to be high enough that the contribution of ambient light to any perceived motion in the image is negligible.  Even if your flash duration is small enough to effectively freeze the bird during the flash, ambient light can cause a blur or “ghosting” of the wings in the resulting image.  Although some ghosting in a hummingbird’s beating wings (or even in other birds) is in many cases entirely acceptable (possibly even desirable) artistically, for the sake of this discussion we’ll assume that the goal is to minimize motion blur as much as possible.

Notice in the above photo that the wings have “shadows”, or “ghosts” above them.  Even though the wings were largely frozen in place by the short flash duration, enough ambient light was present to partially illuminate the wings during the full period that the shutter was open.  Because the wings were in motion during this period, the contribution from the ambient light consisted of a “smearing” of the wings across space.  This is what is meant by “ghosting” in stop-motion flash photography (an unrelated use of the term “ghosting” refers to lens aberrations—see section 3.2).
    Elimination of ghosting in flash photography requires reducing the amount of ambient light that is collected by the sensor, relative to the amount of flash light that is collected (or, alternatively, allowing the ghosting to occur and then removing it later in postprocess—see Chapter 11).  There are two ways to reduce ambient light in this situation.  The first is to actually reduce the amount of light in the scene, either by waiting for a cloudy day, or by shielding the bird from the sunlight via a blanket or other object.  If you’re photographing hummingbirds in your yard, you can use a setup like the one shown below.


In this case, by draping a large cloth between two trees, I’ve blocked the direct sunlight from reaching the feeding station where I hope to attract my subject.  The cloth itself also provides an interesting background for the photo.  Your local textile store should have an array of fabrics with nonuniform textures, in an array of colors.  Cloths with uniform colors tend to make the image look unnatural.  However, solid colors such as white or black can be useful if you intend to replace the background later in postprocess (see Chapter 13), because the solid color will be easier to select with the mouse in Photoshop; the best colors in this case are those that are most different from the colors making up the bird’s plumage, so that “quick select” tools like those in Photoshop can more easily see the difference between the bird and its background.
    The other way to reduce ambient exposure is obviously via manipulation of the camera’s exposure parameters.  The first thing to try is setting the camera’s shutter speed to its maximum sync speed (MSS).  This will allow the full flash pulse to be collected while minimizing ambient collection without engaging high-speed sync; it’s important to leave high-speed sync turned off for this application, since you want the flash to fire in a single pulse, rather than a continuous series of mini-pulses as described earlier.



    Don’t confuse ambient exposure with background exposure.  As demonstrated by the image above, it’s possible to have a bright background and still freeze the wings.  In this case, the background is a white bed sheet hanging only about two feet behind the bird; the brightness of the background in this case comes from reflection of the flash off the sheet, not from a high ambient exposure.  Note also in the above image that freezing the wings doesn’t guarantee that they won’t be blurry: in this case the shallow depth-of-field (DOF) resulted in the bird’s body and the proximal portions of its wings being in sharp focus, while the distal parts of its wings (toward the wingtips) appear to be slightly out of focus (though a small amount of motion blur may also be a contributing factor here—see below).
    Finding the right setting for the flash “power” can be difficult.  Recall that on most DLSR flash units the “power” setting actually controls the duration of the flash pulse (though typically in a nonlinear fashion, due to intensity fall-off over the time-course of the pulse).  To maximize your chances of freezing the bird, you’d ideally like to use the shortest flash duration that still illuminates the bird enough to get whatever exposure level you desire.  The photo below illustrates several issues involved in doing this.


    First, note that the bird has been just slightly over-exposed: the bright white spot above the bird’s shoulder shows evidence of blown highlights.  This photo was taken before I started using the highlight alerts feature of my camera; I now recommend using this feature at all times.  Second, note that while the flash has resulted in lots of fine detail due to the micro-contrast phenomenon (see section 4.3)—note especially the fine feather detail in the dark wing feathers—it has also resulted in very bright reflections from the irridescent parts of the bird’s plumage, which some people may like and others might not.  Irridescent plumages are very common in hummingbird species, so this issue is intimately tied into the problem of photographing hummingbirds. 
    Irridescence, by definition, results in different colors being seen when viewed from different angles.  A secondary effect of this, however, is that irridescent feathers can reflect light very strongly in some directions and only very weakly in others.  As a result, with only a single flash attached to your camera, you may end up with parts of the bird’s plumage which are brilliantly illuminated (sometimes even too brilliantly), while other parts remain quite dark.  This often happens in the bright red gorget (throat feathers) of the males (see the earlier photos in this section for examples of partially-illuminated gorgets). 
    For this reason (and others, which we’ll get to shortly), dedicated hummingbird photographers often utilize multiple flash units set up at different angles around a feeding station, so that more of the bird’s irridescent feathers will reflect light back in the direction of the camera.  This can result in both a greater color range as well as a more uniform illumination of the bird.  Ambient light (not including direct sunlight) would, of course, provide a similar uniformity of illumination, albeit likely at a lower intensity, but the trick here is that the flash units can be synchronized to fire simultaneously, so that the stop-motion effect of a short flash duration (even if the light is coming from multiple flash units during that short interval) can freeze the bird.
    There’s another good reason to use the multiple-flash-unit approach.  With a single flash unit, in order to freeze the bird completely (including the wingtips), you need to use a very brief flash duration, as already discussed.  Using such a short duration will, however, also limit the flash intensity, since flash “power” is effectively the same as duration in most consumer-grade flash units.  Thus, for a bird at a particular distance you may find that in order to freeze the bird you have to use such a low flash “power” setting that the bird ends up being underexposed.  Conversely, in order to achieve a good exposure of the bird you may have to turn up the flash “power” (duration) to a level at which you can no longer freeze the bird completely. 
    All of the hummingbird photos in this section were taken with a single flash, and in all of them the wingtips appear slightly blurred, due probably to a combination of shallow depth-of-field and the use of a flash duration that was too long to completely freeze the motion.  With multiple flash units used in synchrony, you can turn down the flash duration so as to better freeze the motion, and still have enough light for a good exposure.  If you don’t want to invest in a set of four or five $400 flash units, there are several things you can do to increase the effective flash power at short durations.  First, you can get closer to the bird.  Due to the inverse power law for light intensity (section 7.2), getting even just a little bit closer can make a significant difference in effective flash illumination.  Try setting up your hummingbird feeder just outside your window, and then shoot from inside the house (with the window open and the screen removed).  If you set the feeder so close to the window that your lens can’t focus that close, you can use extension tubes (section 3.4) to reduce the minimum focus distance of your lens.  Another way to increase flash intensity is via the use of a flash extender (see section 7.9).  Finally, keep in mind that some amount of motion blur in the wings can actually enhance the image, by making the bird appear more dynamic.

    Although general composition principles (including capturing good poses) are addressed in detail in section 8.1, we’ll just mention a few here that relate specifically to hummingbird photography.  In terms of composition (i.e., where to place the bird in the frame, and what types of backgrounds to seek), the first consideration is to keep the feeder out of the frame (or removing it from the image later via Photoshop).  A hummingbird photo without any visible feeder in frame is generally much more impressive than one showing a hummingbird feeding from a plastic feeder.  Obviously, if you can use natural flowers as your feeders, that’s better still (or you can add the flowers later in Photoshop).  By simply waiting for the bird to back up from the feeder, you should be able to get shots without any feeder visible in-frame.
    The best feeders for hummingbird photography (apart from real flowers) are the horizontal saucer-shaped ones that lack any vertical nectar tank.  I often find that the nectar tank gets in the way when the bird is using one of the feeding ports on the back side of the feeder.  Of course, you can control which feeding ports are used by the bird by taping over all the ports except the one you want the bird to use.  Also, if your feeder has a built-in perch, you’ll likely find that the birds spend most of their time feeding from a perched position.  To force the bird to spend more time in flight, you can remove the built-in perch.  If you feel guilty about making the bird work harder, you can put up a nearby perch so the bird has a place to rest between feeding forays; if you use a tree branch for the perch, you can also get some nice-looking perched shots of the bird.
    Because keeping the bird in focus can be fairly challenging (even with autofocus), I always keep the bird in the center of my viewfinder, and then if necessary crop the image later in postprocessing to move the bird out of the center of the frame (i.e., by cropping with unequal left/right top/bottom margins, so the center of the original image is no longer the center in the cropped image).  Finally, in order to get the birds in a variety of poses, keep an eye out for potential interactions with other birds, or even with insects.  Because hummingbirds often fight over feeding rights at a feeder, interactions between two birds often results in a variety of novel poses.  Also, hummingbirds sometimes spar with larger bees that come to the feeder for nectar, and this can again provide opportunities for capturing something other than the typical hover pose (which is why I don’t try to keep the bees away from my hummingbird feeders).