How to know or calculate depth of field of a photo from EXIF tags?
I want to know the depth of field of a photo, preferably in cm or m.
I know that we can know the camera setting by reading the EXIF tags, but is there a tag directly telling us the depth of field? Or how can we calculate it from some EXIF tags?
Examples would be appreciated. Thanks!
Answer
Calculating depth of field:
t = A * (S/1440) * (D - F) / F^2
The near focus distance = D/(1+t)
The far focus distance = D/(1-t)
And the full depth of field is the difference between these.
The variables are:
A = lens aperture (F Number)
S = camera sensor or film plane diagonal size in mm
D = focus distance in mm
F = lens focal length in mm
Of course, the sharpness of focus is subjective, and is adjusted by changing the constant in the calculation of the circle of confusion (CoC). Here, I have used CoC = S/1440 which is a value that is commonly used.