Depth of field refers to how much of what you are focusing on is in focus. So if you are photographing 20 people in a family group you want the front row and the back row in focus.
The way this is achieved is by using the aperture setting on your camera. This can be set in either manual (typically the letter M on your camera) or aperture priority mode.
The larger the aperture setting number the more of the group will be in focus. The area of “in focus” is both in front of and behind where you are setting your focus. Typically you will focus on the center of the group. So if there are three rows of people in your group, focus on the center row.
If your taking a picture of a landscape or the woods, you may want to focus at the half way point in the scene. Or you can get real creative and focus closer or further away. This will make some objects more or less in focus.
In these images I set my camera with a 85mm 1.8 lens attached (on a tripod in manual mode ) to F22 – this is the longest depth of focus I could get and set the ISO to 1600. Then all I had to do was set the shutter speed so that I got the look (meaning correct exposure) for the scene. In most of these the shutter speed was about 1/30 of a second.
Now a few tidbits:
I set the ISO to 1600 after deciding that I didn’t want to use a shutter speed lower than 1/25 of a second. That was the ISO setting that I needed to keep the shutter speed in that range.
When photographing a snowy scene you should over expose a little bit – so most of these images looked over exposed on my in-camera meter. If I were using a handheld light meter I would have used the camera setting that it gave me
Th exposure triangle – Aperture, Shutter Speed and ISO work together to give you the freedom to create great photos.
Dan Busler is a professional photographer based in Walpole MA