Depth of field/T-stop for 35mm format lens on 16mm?????

Anyone know how to figure depth of field when using a lens designed
for a 35mm film frame, when using such a lens with a 16mm frame?

Seems to me an f 1.8 lens for a 35mm frame, would not be a 1.8 lens in
terms of depth of field or T-stop.

Thanks,

-Chris

>Seems to me an f 1.8 lens for a 35mm frame, would not be a 1.8 lens in
>terms of depth of field or T-stop.

You would be wrong. A lens is a lens is a lens, and a stop is a stop. A
T-stop is about the area of the iris being used relative to the magnification
ratio of the glass. It does not matter what size area of the image plane you
choose to use.

Likewise, depth of field is defined by by what Circle of Confusion you choose
to use, which is the definition of what one considers in focus. Some people
choose a tighter C.O.C. for 16mm ecause it will need to be magnified more than
35mm in projection. But if you keep the same C.O.C. then the depth of field
remains constant.

Mitch