In article <424c22$2012@navajo.gate.net>, jrivera@news.gate.netø says...
>I need some pointers of how to use my DOF preview button.
>How precise is this thing. I can barely see trough when I press this >button. Thanks.

I find the DOF button nearly useless for judging DOF, even with the excellent Nikon F, F2, F3 viewfinders. What it is useful for is
judging the "feel" of out-of-focus areas in the image at different apertures (not all photos should have as much DOF as possible -
I often prefer using the very widest apertures, even for nature
and landscape). It is also useful for judging tonal range in the
photo when using (normally) contrasty film by stopping well down
with the DOF button pressed. (The lower tones drop out in the v.f.,
approximating the more graphically strong image that will be on the
film.) Hope this helps.