How to photograph a flying bird with an SLR digital camera
The first time beginners to SLR digital cameras photograph birds that are in flight, they usually end up with an image that is blurred. For example:

A blurred photograph of a flying bird is good if your intention is to show movement. However there are times when you want a clear unblurred photo of the bird. For example:

Over the last 3 months since purchasing my Canon 400D SLR I've found that with moving birds it's best to set your camera to Shutter Priority. The slower the shutter speed the more blur you will see in the birds wing. For example the first picture on this page had the shutter set to 1/40 seconds. This is a good speed for a moving person, yet not fast enough for a bird that flaps its wings at a quick rate. On the other hand the photograph of the second bird was also set to shutter priority, however this time the speed was 1/500 seconds. This resulted in the bird's wing in particular being more clear and in focus.
You might need to experiment with the shutter speed, depending on the size of your bird and the speed it is flying or flapping its wings. I recommend starting at 1/400 and move up from there if you don't see the results your after first try.
Other SLR camera tutorials you might be interested in:
How to take a good night photograph of city lights
Composition tips for better photography
UPDATE: Our tutorials for photographers are now being continued over at SLR Photography Guide.
