Clean, Smooth, Buttery, Creamy, Delicious Backgrounds! Backgrounds? Yes backgrounds. In wildlife photography the background is just as, if not more important, then the subject. In most situation, the background is what separates a great wildlife image from just another snapshot. So how do we get those buttery backgrounds?
To get nice blurry out of focus backgrounds we need to understand how to control depth of field, then how to use that knowledge to our advantage. The depth of field is the area in the image that is in focus. Everything closer to the camera, or further from the camera, then this distance will be out of focus. Another thing to remember is that the further away from the area that is in focus the blurry it will be.
The first way, and the one most photographer use to control depth of field is the lens aperture. The basic rule is the wider your aperture or the lower your f-number is, the shallower the depth of field. In my photography I generally want as small of a depth of field as possible, so I use the widest aperture possible with my equipment. A 300mm lens focused at 5 meters at an aperture of f/22 will have a depth of field of close to 40 cm, but by just opening up the aperture to f/2.8 we can reduce the depth of field to just 5 centimeters! One benefit of this is it allows me to use the fastest shutter speed possible to freeze any movement.
The second , and less know way to control depth of field is through the focal length of the lens. The longer the lens, more millimeters, the narrower the depth of field will be at a given aperture. For an example of this, let’s take a look at the difference a 50mm lens and a 600mm lens at an aperture of 5.6 on a full frame camera set to focus at 5 meters. The 50mm lens will have a depth of field of approximately 4.25 meters, while the 600mm’s depth of field will only be .2.3 centimeters! This is why it can be difficult to get tack sharp focus on the eye of a small bird. If the camera focuses on its beak the eye will be soft.
The third thing to consider is the distance between your subject, and the background. The greater the distance between the limits of your working depth of field and the background, the more out of focus and soft any elements in the background will be.
So let’s look at how I use this information in the field. Imagine that I am looking to get an image of a Red-winged Blackbird singing on a cattail. After locating a subject I would then look for an angle that would allow me to place any background element as far away from the Blackbird as possible. I would then set my aperture to its largest setting and adjust the shutter speed and ISO to get the proper exposure for the bird. This setup would allow me to seperate the bird from the nice creamy, out of focus background.
One more tip. Most birds are creatures of habit, and will usually return to the same spot to sing, or area to feed. Take your time, asses the situation, find these spots, and then decide which one will give you the best background. Then set up the shot, and wait for the bird to return.