Oh? Sorry, I forgot to read the avertisements, and was simply depending on a technical background. I will try to do better next time and use buzz-words instead of explainations.
Ciao, Graywolf http://pages.prodigy.net/graywolfphoto ----- Original Message ----- From: "Michel Carr�re-G�e" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, March 18, 2003 11:33 AM Subject: Re: Good-bye Pentax > T Rittenhouse a �crit: > > USM = Ultra-Sonic Motor. What that means is instead of using a DC motor they > > use an AC motor that works at ultrasonic frequencies (100khz and above). The > > extremely high frequency of the power source (generated electronically) > > allows the motor to be very small and light. That means the motor can > > accelerate much faster than a low frequency or DC motor. Used in a lens that > > translates into a lighter, and faster focusing, lens . However since the > > motor has to move a mass of glass the overall improvement is only > > incremental in the real world. HSM (Hyper-Sonic Motor) means the same thing. > > 10% real improvement, 90% hype <g> > Usm/Hsm combine fast motor, direct-drive (no mechanism) and step-motor > > Michel > >
