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To stack or not to stack

Started Sep 26, 2019 | Polls thread
Pixel Pooper Veteran Member • Posts: 3,978
Re: Larger DOF with larger sensors (not a typo)

gardenersassistant wrote:

I can see that the lens without the teleconverter has a wider angle of view, and that the background has a wider field of view. But I'm scratching my head a bit about the implications of this regarding the DOF. The field of view at the focal plane is the same, so Isn't the difference in DOF being caused solely by the difference in exit pupil rather than the difference in angle of view or the difference in field of view in the background?

Depth of field depends on the angle of the cones of light from the subject passing through the aperture.

To keep the same magnification with double the focal length, you must double the distance to the subject, so the light cone becomes narrower unless you also double the aperture diameter, which gives you the same f-number.

To keep the same magnification with the same angle of view, your subject distance is the same, so the light cone has the same angle at the same aperture diameter. With a smaller sensor, the same angle of view requires a shorter focal length, which gives you smaller f/number.

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