nospam wrote in
:

In article , +++ATH0
wrote:

One other factor to bear in mind: the depth of field varies with
lens focal length, not field of view of the subject.

actually, it's aperture.

actually, it's the ratio of focal length to aperture.

nope. depth of field is a function of physical aperture.

what you describe is f/stop, which is used for exposure purposes,
and in some cases (usually movies), t/stops are used, which is
actual light transmission through the lens, not a simple ratio.

Are you claiming that focal length has no bearing on depth of field?

for the same subject size and same image quality (coc), no.

That's an interesting viewpoint.

not really. it's just math.

No matter what the focal length of the lense is, the further away the
focal plane is, the greater the depth of field will be for any aperature.

As an example, if one is taking a head and shoulders portrait with a
large aperature, it is quite likely that part of the subject will be out
of focus slighty. Moving back a few feet with the same lense and
aperature will result in a deeper depth of field, so that all of the
subject should be in focus. The drawback is that the image size will be
smaller, and thus require more enlargement to obtain the same size image,
with the resulting loss of resolution with the enlarged image.