Depth of focus for video recording How can I calculate the depth of focus (Depth of field, DoF) for video recording?

There are some tools around that calculate the DoF for different camera types depending on focal length, f-stop and subject distance, e.g.


http://www.dofmaster.com/dofjs.html
http://www.cambridgeincolour.com/tutorials/dof-calculator.htm.


My assumption is, that the DoF for video recording is bigger than that for photographs, because video is recorded with lower resolution, and therefore a higher degree of unsharpness can be accepted without visible effect.

My idea was to calculate the size of a single pixel and use this size as "circle of confusion" parameter.

My question: Are these assumptions and the example calculation below correct? What is a reasonable way to calculate DoF for video?

Example: 


Canon EOS 600D / Rebel T3i
f2.8
16mm
object distance 2m
recording format 1080p


From the 600D's sensor size (22.3 mm x 14.8 mm) and video resolution (1920x1080) I calculate the pixel size to be 0.0116 mm x 0.0116 mm, or 0.016 mm in diagonal.

Entering these numbers into dofmaster, I get 1.6 m as a result (1.48 m ... 3.08 m).

What surprises me is, that using the camera model directly instead of the CoC, the result is 2.02m, which is bigger than that vor video.

Accordingly, when calculating for a video resolution of 720x576, I get a DoF of 146m.
Well, your calculations appear to be correct, but the only calculation that isn't exactly known is the pixel size of your camera sensor. Either your calculation of the camera's pixel size on the sensor (at least when filming 1080 video) is off, or their recorded circle of confusion of that sensor is off. Or both. Though I find it more likely that their stored CoC value for that sensor is based on what is "reasonable focus loss" not on the actual pixel size, and so they have a larger CoC value than what you consider to be reasonable, as your reasonable is that the CoC is no bigger than a pixel.

Either way, calculating the differences based on resolution shouldn't be an issue. In the spirit of better safe than sorry, use your own calculation of the pixel sizes (0.016mm with the DoF result ~1.31m) as a basis. If you're going to test for half the resolution of 1080 (being 540) then you'll double the pixel size calculation (0.032mm) resulting in ~4m DoF.

To calculate for 720x576 (which is 576 resolution, not 720 resolution. Careful with that) you'd do (1080/576)*0.013mm = 0.03 (new CoC for calculation resulting in 3.44m DoF).

I'm not sure how you got 146m as a result though. Perhaps you input the wrong circle of confusion value?