[BC] M aybe an alogue is better

[Jason R.]

What  I mean is that alot of the self-focusing cameras (Like, a Sony
HandICam,etc.) Use some sort of infrared to determine the distances to
object in their field of view.  At least the older autofocus stuff did.
(Cannon EOS 35mm was good example, and they have the description in their
use manual.)

  When you get a picture on a small home camera now, many times you will see
more than one 'green box' light up in the LCD viewfinder... those happe to
be the items in the picutre that the camera 'could' focus on... maybe even
both in some instances.. but many cameras will allow you to pick your focal
distance on some single item in the FOV, then hold it while you pan to a
different place in the same field of view.

  When these older cameras can't accurately determine the correct focal
point in that particular field quickly enough, you will be able to see them
shift focus back and forth in the view finder... the most obvious effect
comes when there is just the right difference in distance between a
'foregrund item' and a 'background item'... the camera will first focus
onthe person infront of the bldg for example, but, finding that the bldg is
nearly in focus, try to focus on the bldg.  But finding that the person is
nearly in focus, shift back to the person.  But findign the bldg nearly in
focus, shift back to the bldg....   repeating this several times before
deciding on the best compromise in different focal lengths...

  Get it now?

  Very annoying to see happen on live TV.   Most taped programs don't seem
to exhibit this.  Not all stations exhibit it at all, so I suspect it has
somethig to do with specific cameras...

Jason
> I also don't know what you mean by "infrared zone."  The focus doesn't
> use infrared, and we cannot see it.
>
> --chip