Originally Posted by
rpcrowe
I am a great advocate of letting the camera do as much of the exposure calculations as possible. However when birds are flying by changing exposure value backgrounds, the camera metering will constantly be trying to match the exposure for the background.
However, if you use substitute metering with manual exposure, the exposures will not be hopping around and so much influenced by the background.
A substitute metering subject could be the grass or other foliage. Once you determine the exposure for that subject, you have a "starting" exposure for your birds.
Two advocates of substitute metering are Bryan Peterson, author of, "Understanding Exposure, 3rd Edition: How to Shoot Great Photographs with Any Camera" and Jim Nieger, Florida bird photographer and bird photography instructor.
After you get the "starting exposure" you then need to adjust your exposure for the birds you are shooting. Darker birds need more exposure while white birds require less exposure. Note, this is opposite of how you would compensate for the different toned birds when using reflective metering off the birds. The reflective meter will attempt to turn both blacks and whites into gray and you need to increase the exposure for the white and reduce it for the black.
The amount you need to increase or decrease the exposure depends on the color of the bird and the quality of the light. As explained by Jim Nieger for shooting white birds such as egrets, "If it’s just after sunrise and the light is very soft, the amount to decrease exposure may be only 1/3 of a stop. If we photograph the same bird at high noon, the amount we need to decrease exposure by will likely be as much as 2 stops."
I would like to offer my own take on substitute metering. An grey metering target will provide a standard exposure for the light in which you are shooting, as long as the subject will be in the same light as the card. However, everything could be simplified by using an incident light meter which "should" give you approximately the same exposure as metering off grass or a gray target.
Just remember that your exposure compensations are opposite from metering off the bird. Dark = increase exposure, white = decrease exposure.