The “A” Word
Aperture. There I said it. Probably the most misunderstood concept in photography and why not, large is small, letters and numbers living together. The world is upside down. It makes as much sense as a politician at confession. Ahh, but it makes perfect sense and maybe that is the problem, logic can be hard to follow at times. First of all large number means a small aperture. Aperture is the size of the opening that lets light into your camera and onto the sensor or film. So why in the world would one want to change the amount of light going into the camera? Wouldn’t it be best to have as much light as possible all the time? That actually makes a lot of sense except for the fact that optics also have the size of the aperture controlling the portions of the scene that are in focus, also known as depth of field. The smaller the aperture, the less light but also the larger amount of area in the scene you are photographing that will be in focus. You can read more about depth of field in my previous post “A fine line Between Clever and Stupid“. Often we hear about a photographer who shoots “wide open” This means that photographer likes to shoot at the widest aperture (small f-number) letting the maximum amount of light in the camera and the least amount of the scene in focus. That tends to lead the viewer right to the subject of the photograph.
So now lets bring it all back to bird photography because as you might imagine aperture takes on a different level of importance for us. Some of the time we have little choice. You will have to shoot wide open just to have enough shutter speed to make a shot. Often the case when making birds in flight photos. The silver lining when backed against the wall like this is that you are also rarely very close to the subject and thus a razor-thin depth of field is less of a concern. When shooting slow moving and stationary birds it is important to increase that f-number (making a smaller aperture) to increase the depth of field so that you will be sure to get everything you want in focus. As you get closer to the subject this becomes more important. For example, if you are making a portrait of a Brown pelican and want to have the tip of its bill and the eyes in focus you are going to need to go with a very high f-number for the aperture setting. With a 500mm lens you will need to stop down to about f16-f20 to get the shot you need.
So the moral of today’s post. “There is no set it and forget it” when it comes to aperture so make sure you are confident in knowing how your aperture setting is going to affect your image and be mindful of your f values every time you change the scene.