DOF Calculation Variables

[Pawlowski6132]

When using these (http://www.dofmaster.com/dofjs.html)types of tools and calculators, I assume Subject Distance is distance from subject to film plane and NOT subject to lens?

thanx,

joe

[Mark Barendt]

Yes

[Jeff Conrad]

The subject distance is usually from the front nodal plane, because the lens's nodal space isn't known. The DOFMaster calculator appears to follow this practice. Except for closeup work, it usually doesn't matter whether the reference is the image plane or the front nodal plane.

[GPS]

Jeff already gave the correct answer, so it is roughly the distance of the subject to the lens.