The Depth of Field Myth

By Gary Gray

Originally published in 2007 on Have Camera -Will Travel, I’ve since made a few edits to this article and am republishing now as one of my most popular articles from the past. It is still relevant.

There seems to be a common belief that the camera with a full frame sensor will provide the photographer with more or less, (depending on which techno-wiz camera geek you talk to) depth of field than a cropped sensor camera such as the EOS 30D, which can be viewed either as an advantage or a drawback (depending on which techno-wiz camera geek you talk to.) On some internet forums you’ll find never ending debates over this camera vs. that camera and the difference in depth of field one format sensor will provide you over another.

Forget about all that. If you’re like me, I don’t need nor do I want to take a ruler and a calculator with me when I’m strolling around with my camera, so I can calculate a minuscule depth of field change between camera bodies. What ever your need as a photographer may be, I am here to show you that the different camera bodies will provide virtually identical depth of field when using identical focal lengths and the same exposure. The more depth of field that the Full Frame sensor supposedly gives you is a myth. Functionally, from a photographic standpoint there is no difference.

Below are two photographs, taken one right after the other, using the EOS 30D and EOS 5D with a Sigma 105mm Macro lens, pointing at a yardstick from the same exact distance using a tripod. I’m manually focusing on the 20 inch mark of the yardstick. The only obvious difference between the shots is the field of view (not to be confused with the depth of field.) The EOS 5D will give a wider field of view than the 30D using the same focal length lens. If you examine the depth of field provided in both shots by tracing the yardstick from the 20 inch mark, you’ll see that the focus field is identical.

Sample photos depicting depth of field difference between a full frame and cropped frame camera sensor.
Image on left EOS 30D, APS-C / Sigma 105mm Macro f2.8/ISO 100
Image on right EOS 5D, Full Frame / Sigma 105mm Macro f2.8/ISO 100

I can’t think of any better way to explain this than by using actual photographs. The depth of field is the same, the field of view is different.

The crop body does not modify the depth of field.

Put the calculator away and take pictures.

Nuff said…