Depth of Field for Portraiture

One of the basic laws of imaging is that only one part of a three-dimensional object can be truly in focus at the image plane and areas that are located in front and behind that focus plane will appear more or less in focus.

At the point of critical focus, there is a range of acceptable focus that is one-third in front of that point and two-thirds behind it. And that my friends is what depth-of-field is all about.


Depth of field is affected by the camera’s distance to the subject and increases as the lens aperture is stopped down (larger f numbers) and decreases as the lens aperture gets larger (smaller f numbers) and the camera to subject distance decreases.

tia.dof.colorThe color digital infrared image (above) was made with a Canon EOS 50D that had been converted to infrared-only capture by LifePixel and an EF 85mm f/1.8 lens. Exposure was made in Aperture Priority mode to maximize depth-of-field at 1/200 sec at f/16 and ISO 400.

So what do all of those colors that Tia is wearing (and her hair) look like under available light using conventional capture methods? This image was made just a few minutes before the infrared shot using a Canon EOS 60D and EF 28-105mm lens with an exposure of 1/60 sec at f/5 and ISO 200.

If you want to save a few bucks when converting your camera to infrared when ordering a conversion from LifePixel, use the coupon code “farace.”

Author: Joe Farace

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