"Jul" writes:

Using Auto - a camera sets for me the aperture and shutter speed .
If I want to do it myself, how to set right parameters? Does it only
practice or exist the rules that will help me to set the "correct" or close
to correct params?

There are rules of thumb; the basic one is the "sunny 16" rule, which
says that at ISO I, your basic exposure for a subject in full
sunlight is a shutter speed of 1/I and an aperture of f/16. There
are also standard apertures for cloudy days and "open shade" (in the
shade but exposed to a large area of sky). (So, with the camera set
to ISO 100, a shutter speed of 1/100 sec and an aperture of f/16 is
about right for a subject in full sun).

These used to all be printed on the data sheet that came with film,
and then inside the film boxes, but I haven't seen them in any digital
camera manual.

In digital, experimenting is free. With some practice you can judge
exposure fairly accurately on most LCDs, and if your camera has a
"histogram" display you can verify that exposure is correct very
accurately.

if my subject 5 ft and 500 ft away from me and at both cases at the center
of the frame how the params will change , and if I need at both case keep
only subject at focus, does it possible?

Distance doesn't directly affect exposure, if that's what you're
asking. (In situations with a LOT of distance and dirty or misty air,
distance affects contrast a lot, and sometimes affects exposure
indirectly.)

Keeping "only" the subject in focus requires limiting depth of field
(and possibly composing the picture to eliminate other things at the
same distance as the subject).

Can reference me to any sourse where I can find answer on these and
related questions (not only that smaller aperture increase DOF)?

If you're serious about photography, I'd start with the Ansel Adams
Basic Photo series -- books called The Camera, The Negative, and The
Print particularly.

Somebody needs to write a series of that quality to introduce people
to photography digitally; so far as I know, nobody has yet (and
digital has a lot of advantages particularly for teaching -- the
ability to see results quickly lets you really tie what you did to
what the result looked like in your head).
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/