I gather many photographers
never use depth of field preview.
Some can't even see the purpose; for my wife it just "darkens the screen".
And I'm not sure they know or care about the DOF scale on manual focus lenses.
Of course an experienced photographer knows what sort of DOF
they'll get at any given aperture with various focal length lenses.
I'm pretty confident most of the time, or I could use the lens scale,
but I prefer the confirmation DOF preview offers, and I seldom opt
to use an SLR without this feature. Wanna buy an ME Super?
DOF preview is a
major reason I recommend a Pentax KX or KM over a K1000.
If someone
really likes a K1000 I always try to steer them to a KM instead.
Chris