TimS Loc: GA

I use a canon 1.4 teleconverter (TC) with my 70-200 sometimes. Is depth of field related to the actual aperture of the lens when I take the shot or the effective 1-stop slower aperture as a result of the TC? I'm assuming when I shoot wide open, the aperture is actually open to the 2.8 setting and not the 4.0 setting as reported by my camera. In other words, if I'm at 200 mm and the camera says aperture is 4.0, is the opening actually 50mm or 71.4mm? If it is 71.4 then I would tend to believe that the physics of the lens would dictate that depth of field is calculated using the actual (not effective) aperture. Any thoughts?

BigBear Loc: Northern CT

The aperture value that is on your camera with the tc is what it really is. The tc changes the aperture by lengthening the distance between the lens and sensor.