An Online Guide - Part 2:
The Outdoor Studio
Although we've decided to use flash for our hummingbirds, we'll typically be working outside in daylight. So it may not be immediately obvious how to deal with flash and daylight at the same time. The simplest solution is to ensure that the total flash output is several stops brighter than ambient. If you do that, then all the light in your picture will come from your flashes.
To put it another way, you want to work at a shutter speed and aperture that would give you several stops of underexposure if your flashes didn't fire and only the ambient light reached the film. (A typical setting might be 1/200 s at f/16 with ISO 100 film in the shade. That can be achieved with several flashes positioned as I'll describe in Part 3.)
This is exactly like shooting at night, with only flash to light the scene! It is also like shooting with flash in a studio, where strobes are your only light source. In fact, we are going to construct an "Outdoor Studio" in miniature to get our images, and then entice the hummingbirds to pose for us!
Can I Mix Flash and Ambient Light?
While it's easier to set up so that all your exposure comes from your flashes, it's not necessary. Sometimes the ambient light is too bright to ignore. Other times you may choose to include it.
When flash and ambient light mix, you'll see what's known as "ghosting." Thats because the photo is really a sort of "double exposure"one image from the ambient light for the entire time the shutter is open (e.g. 1/125 sec) which will have wings blurred; and another superimposed image of frozen motion from the strobe.
Ghosting can impart an element of motion, which may be desirable. But it requires more attention to balancing the ambient and flash levels. With a flash meter, this is not hard to do, as long as your ambient light level stays constant.
Studio Control in an Outdoor Setting
One advantage of shooting in the "outdoor studio" is that you have almost complete control over the lighting. You decide where to put the lights, what backgrounds to use, and where you'll shoot. And proper placement of the lights is crucial for getting the best shots of iridescent hummingbirds. Of course, this assumes you can entice at least one hummingbird to cooperatebut they're usually pretty obliging if you feed them.
The heart of our setup is usually a sugar-water feeder, with flashes positioned 1-3 feet from the subject. As you'll see, part of the challengeand funis hiding the feeder and placing flowers and other props to make your setting look natural. You can also set up at a plant naturally favored by hummingbirdsand further entice your subject by supplementing the natural nectar with a spike of sugar water. Your setup can be as simple or elaborate as you desire.
Getting Enough Flash Output
By now you can see that there's a tradeoff between flash output and duration. To freeze wing motion, your flashes need to operate at 1/8 to 1/32 power. But you also want a lot of light from your flashesto effectively compete with daylight, and to allow small apertures for maximum depth of field. There are several ways to cope with these competing demands:
1. Arrange for your subject and background to be in shade (less ambient light to compete with).
2. Use as high a flash sync speed as possible.
3. Use more flashes, and position them close to the subject, perhaps two feet away or less. Remember that the Inverse Square Law tells us that if we cut the distance in half, light intensity at the subject will increase by a factor of four. And of course doubling the number of flashes will double the output, giving you one more f/stop.
Once you've created your setup, you can place your camera on a tripod 5-10 feet away, sit in a comfortable chair, and wait for the diners to come. But first you need to decide on the proper positions for the lights, and then determine the correct exposure. Next ...