Originally posted by Stringmike ..as already discussed may be Pentax's answer to a simple direct electric drive focusing motor. It does not operate at ultrasonic frequencies but from the patent appears to use pulsed direct current (DC). The design drives the focus ring by magnetic coupling and is mechanically very simple. The electronic drive circuitry is also lower voltage and simpler than those used for ultrasonic motors.
My guess would be that the poor reliability of SDM has given Pentax an incentive to go with a new design.
Mike
So, if the new patent uses pulsed DC curent, then this lens might be the first with the new drive. Or, it is just a DC micro motor (like all other SDM lenses I understand), and the DC code is not to indicate a new drive, but a revamped micro motor drvie.
Maybe Pentax is going to start using true ultrasonic ring motors. These use high frequency AC current. So maybe we will see AC SDM lenses for the true ring motors, and DC SDM lenses for the micro motors.
Either way, Pentax has, or is changing the SDM drive system.
Someone needs to take a lens apart and tell us what they find inside.
I nominate Falk, as he is at Photokina.