An Experiment in Deapth of Feild...

I was experiencing a bout of insomnia, so I decided to take a few photos that might help some people to understand "depth of field" a little better.

Very basically; depth of field is how much of the image, in front and behind the focal point, is in focus.

One of he determining factors involved with depth of field is the aperture setting used. The smaller the aperture (larger the F#) the more of the image will be in focus. The distance from the subject and the focal length of the lens can also play a part with depth of field.

In my examples, I maintained identical exposure setting in every frame except for the aperture setting. Hopefully, this will better illustrate my point.

The setting was the top/head of a tripod placed about 2 feet from a book case.

I used my Canon EOS 50D with a Canon EF 50mm lens and made use of the pop-up flash on the camera.

I kept the ISO setting at 100, a shutter speed of 250th of a second, and adjusted my aperture for each shot. The focal point for each photo was the screw on the tripod head. I started with an aperture of f/1.8, moved to f/2.8, f/4.5, f/8, f/13, and finally f/22.  Here were the results...

f/1.8

f/2.8

f/4.5

f/8

f/13

f/22

Since both the ISO setting and the shutter speed remained the same in each shot; the exposure is incorrect and you will notice the image gets slightly darker in each frame. But hopefully the difference in the depth of field is apparent.

I hope this is helpful for someone.

--- Mark ---