Freezing the scene, by Lou Coetzer, uses an image from an exciting Etosha encounter to help you start to come to grips with depth of field.
The elephant bull appeared at the Etosha waterhole like a silent ghost, surprising not only me but also the male lion who had been napping nearby. Flapping his ears dramatically, the elephant signaled to the big cat that his presence was not appreciated. The lion quickly rose, and as it retreated and briefly passed in front of several zebra and giraffe in the background – it made for a very dramatic scene.
I had mere seconds to try and capture this overwhelming scene in its entirety, and I couldn’t do so without having the crucial elements in focus. Depth of field was going to be key. I immediately grabbed my camera with a short lens and moved the centre-focusing sensor horizontally to the left to focus on the bull elephant as it was the closest subject to me. I then dialled to a smaller f-stop to make sure that I would have enough depth of field. In the spilt second of the decision making process my overriding concern was maintaining a high enough shutter speed to nail the shot.
The Lesson (DSLR)
1 Use the highest ISO that still renders a high quality, noise-free image. This helps ensure the shutter speed is sufficient to freeze the action. Potential noise in the image due to higher ISOs can typically end up in the bin.
2 Be prepared to move your focusing sensor manually across your camera frame as required.
3 Always start your management of depth of field by focusing on the front element or the front subject in your image (there is almost twice as much area of sharpness behind the camera’s point of focus as there is in front of it).
4 Dial in the appropriate f-stop. A smaller f-stop, which equates to a larger f-number (such as f22), will allow more depth of field. It will be a great advantage if the custom setting of your camera will allow you to change the f-stop without taking your finger off the shutter release.
5 If your camera is equipped with a depth of field preview button use it all the time. Again, it will be a great benefit if your camera allows you keep to your finger on the shutter release button while you are checking depth of field.
6 Think about deliberately under exposing the image. In this case (EV -1.3) it not only prevented the whites of the zebras being washed out, it – crucially – also increased the shutter speed.
7 Always use the aperture priority or AV mode of your camera.
The Lesson (Non-DSLR users)
If you are using a camera that does not allow you to move the focusing sensor around or check the depth of field (DOF) via the DOF preview button, you are most likely using a compact camera equipped with a rather powerful zoom. The golden rule will then be to simply use the central focus sensor to focus on the closest part of the subject or the closest subject to you. Zoom in as far as is feasible.
Learn more about Lou Coetzer, his images and the photographic-workshop safaris he runs at www.coetzernaturephotography.com