> fra: Toralf Lund <[EMAIL PROTECTED]> > > DagT wrote: > > > Of course, we don´t hear ultrasound, but some animals do. > > So, if you try to shoot them with a Canon, they'll run away???
Yes, but it depends on the frequency. Dogs hear ultrasonic sounds far beyond our senses. > Is there really anything ultrasonic about it, by the way? Yes. I read the main patent once. The motor is a ring of piezoelectric (?) material which is is set in a wave movement at an ultra sonic frequency. This wave movement pushes the focus mechanism. > > Toralf was thinking about whether they were harmful. I wouldn´t > > worry too much there, but... > > Actually, I was mainly trying to be sarcastic - although I do know that > some now claim that the ultrasound used for medical purposes may > actually be quite harmful. I know, they are limiting the use on unborn babies in Norway now. > I just think it's weird, and slightly annoying, how some people here > seem to be obsessed with this ultrasonic thing. Don't get me wrong, if > you think that Pentax ought to make quieter (or faster) AF, then I > follow you, although it doesn't really matter a lot to me - but implying > that Pentax makes inferior cameras because they don't call their AF > system "ultrasonic"... I agree, as long as the AF works good enough I dont care how. > BTW, hasn't Pentax made the AF quiet*er*? I haven't really taken much > notice... But I think it would be in their tradition to just release > something a lot better in that respect as just the next generation of > their system and a result of continual improvement, rather than a new > "feature" they make a lot of fuzz about. And I prefer the Pentax way, > there... Same here. Personally I dont care much about AF at all. It nevere focusses on what I want anyway .-) DagT
