Filling The Frame
Get up close and personal with your primary subject
Birds are notoriously bad photographic subjects.
They don't stay still for very long, they jitter all over the place when they are in motion and they're tiny relative to their surrounding environment.
This last attribute makes it hard to fill the frame when you are photographing one of our avian friends.
How To Fill the Frame
In this case, the frame is the edges of the photograph you take. The expression "fill the frame" does not mean that your photograph should be packed with visual information.
It means that your primary subject should be large enough in the photo to stand out from the surroundings.
It also means that you should isolate the primary subject of the photo, so that there is not a lot of other visual information competing for attention.
Get Up Close
The easiest way to fill the frame is to get right up next to your subject. If your subject is a leaf, make sure it is the largest element in the photo. If your subject is a house, fill as much of the photo as you can with it. If you're making a portrait with a competing background, get close to your subject and eliminate as much of the background as you can.
In some cases, it is not feasible to get close to your subject since you might get mauled: when the object of your photo is a polar bear, for example. In other cases, approaching your subject will scare it off — this is especially true with birds. In these cases, the only way that you can fill the frame is with a telephoto lens or a lens with a large zoom ratio. Many nature photographers use lenses at lengths of 400mm and 600mm to get in close to their subjects.
Why Fill The Frame?
The most important reason to fill the frame is to make it clear to your viewer what the subject of your photo is. Sometimes this will be important to you and sometimes it won't.
Example 1 — Frame Not Filled
You want to take a photograph of your friend at the Grand Canyon, and you want to make sure that some of the canyon gets included. In this case, it makes no sense to fill the frame with your subject, since that would remove the context of location from the photograph. However, you DO want to make sure that your friend and the canyon are the only elements in the photo. If you are too far away and a lot of other tourists make it into your shot, it might be hard for others to tell which person is your friend.
Example 2 — Frame Filled
You want to take a photograph of your favorite hamster in his indoor cage. If you capture the entire scene, there will be a lot to look at: the background, the cage, whatever the cage is sitting on, etc. It might be hard to tell you were going for a photo of the hamster. If you fill the frame with your hamster and eliminate all the background noise, the subject of your photograph will become completely clear.