Monday, August 30, 2010
When I press the shutter release on my camera the flash sends out a short burst of light that the camera’s metering system uses to determine how long the main flash pulse is going to fire. If the subject fills the frame, or there is something close behind the subject for the light to bounce off of, then odds are the light meter in the camera will be able to correctly determine how long to turn on the flash to give me a properly exposed image. But if the subject doesn’t fill the frame, and there isn’t anything close in the background for the flash to bounce off of, then the light meter is going to turn on the flash so long that I’ll probably get an over exposed image. That’s how Evaluative–Through The Lens (E-TTL) flash metering works. To get the most consistent results with E-TTL I need to get as much of the metering flash burst back into the lens as possible, and that’s what I’ve done with this field studio:
The trick is to initially bate the flowers that the bees are feeding on. Once the girls get into the habit of looking for the corn syrup (believe it or not it will take them a while) simply cut a piece of the flower petal, place it in a convenient spot close to where the bees are feeding, and set up a back drop (in this case a leaf). You’ll get better E-TTL metering since there’s a backdrop to reflect the metering pulse back into the lens, and you’ll have more time to concentrate on framing and composition because the camera is taking care of the exposure.
You can do a similar trick with dormant subjects –just cut the perch that they are using and hold it up in front of a leaf (or anything that will reflect light back into the camera and give you a pleasing background):
Footnote: The light meter in most cameras samples the frame at the same areas as the auto focus system. So a camera with more auto focus points will typically have a more accurate light meter.
Until next time, happy shooting :)