No, wait a minute, don't tell me, I got that backwards.  I think my brain
has been frozen by the cold temps (minus forty-eight degrees Celsius after
factoring in wind-chill).  It's the second time today I got something
backwards.

The thing to do would actually be to move in and zoom out;  that should
increase depth-of-field.  Anyone who's played around with dof and
point-and-shoots enough to know?

Somewhat embarrassed,
Dudley

No, sorry.  Ultimately, DoF is related to the ratio of object size to
image size.  The math is formidable, but basically if you fill the frame
with someone's head, then step back and zoom till the frame is again
filled with their head, the Dof will be unchanged.  Perspective will
change, but DoF won't. Provided you haven't changed the aperture, of course.

Colin D.

snip

Depth of field is greater at distances than close up. For example, (these
numbers are made up) focus at 4 feet and DOF might be from 3.5 feet to 4.5
feet. Focus at 10 feet and DOF might be from 7 feet to infinity, for the
same f/stop.

Longer focal length lens generally have less DOF at a particular distance
than short focal length lenses. So for maximm DOF, use a wide angle (short)
lens.

I grabbed a couple lenses off the shelf, and made these rough observations
(these are 35mm film camera lenses):
35mm lens, f/16, focus at 8', DOF scale says 4' to infinity
50mm lens, f/16, focus at 8' DOF scale says 5' to 15'
135mm lens, f/16, focus at 8', DOF scale says 7.5' to 9'
Hyperfocal distance (the distance at which depth of field is the closest
distance to infinity) for the 35mm at f/16 is 8' (4' to infinity), for the
50mm at f/16 is 15' (9' to infinity), and for the 125mm at f/16 is 75' (40'
to infinity). These figures are not the result of testing, but rather
reading the tiny scales on the lenses, so there may be some margin of error,
but the general idea is there.

Moving back and zooming in (or moving in and zooming out) will change the
prespective of your subject. For example, back when cars were boats and had
big tail fins, advertising photos were often shot with a slight wide lens,
closeup at a low angle. This made the car look even longer and the tailfins
even bigger. This was not  caused by the lens, but by the closeness and the
angle. Conversely, a long lens tends to compress foreground and background.
Again this is not because of the lens, but because the foreground and
background are so far away.

As for using your zoom and/or teleconverter to increase DOF, that's another
ball of wax. The construciton of a zoom lens can have effect on the DOF.
Whenever possible, I like to stay with prime lenses; usually they are
brighter and better quality (usually!).

I have a lot to learn too. As this technology advances our learning never
ends. My real preference is simply to improve my photos and try to share my
limited knowledge.

I am in a crazy process of selecting about 30 images for a website, from the
thousands I have on my drives.
For some reason I think that 30 is a good number. One of the major issues I
face is trying to somehow find some unification of the images so they don't
look like the hodge podgy they are.

snip

Don't go running to the Patent Office!
Check out "Lindahl", that's the brand matte box that I have. This is a
bellows like device that mounts to the front of the lens. Mine extends about
four inches out, where there is a slot for the vignetter plate. It's a piece
of glass about 4"x4"; the center is clear, around the ede there is a black
pattern that gets more dense the closer it gets to the edge. There is also a
slot close to the lens where I put the diffuser.
Instead of the glass vignetter with dark edges, there is also a white
translucent plastic vignettter with a hole in the center. When I use this, I
place a small strobe about a foot in front and below the vignetter. The
flash lights up the vignetter, giving the picture whute edges.

I've never seen one, but you could make one by drilling the centre out
of a plain plastic ND filter.