Those numbers are very different from what I see on other DOF calculators ...
I did say in #89 that I prefer to use the term 'critical focus', as its more descriptive of what we're actually measuring. The reason they're different is because, as CambridgeInColour says:
An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot. […] A different maximum circle of confusion also applies for each print size and viewing distance combination..
Bart's figures are based on a
max output size/ppi figure for a selected 'quality' setting. In the case of the Fuji that comes to a print size of 16x12 inches, approximately, at 291 ppi. Not 10x8. Bart's calculator is far more extensive both in the number of inputs and variables (almost to the point of confusion for us lesser mortals) as well as the consequent output.
If I were to insert the 10x8 print size the DOF does indeed change, though still not quite as deep as the Cambridge ones.
One may vary the CoC, but I believe Bart is initially using a CoC quite close to the sensel pitch of the camera. For the Fuji thats about 4.8 microns but the CoC diameter is automatically updated based on the sensor / pixel pitch, output quality requirements, print size and camera settings in [Section2]
The basic tenet is that for a given max output size the DOF will be in accordance with his calculator. Any smaller sizes will obviously have greater apparent DOF. A quick search on Bart van der Wolf's posts re DOF will explain a lot more than I'm able to do in a quick post.
Practically speaking though, and assuming an output size of A2, I've found Bart's figures far more representative of real life 'critical focus', at least as far as portraiture is concerned.