Originally posted by EricT Svein, you say that you got a quote for repair abroad. Where was this? Did you check if the Norwegian repair center, Camera & Videoteknikk AS, could do the repair?
I got a quote from Fovi at the time the lens first failed (2009). This was at the time when Pentax was restructuring its distributor and service network. I was told SDM lenses had to be to Germany for repair, and the cost was estimated to 2500-3000 NOK (about 400-500 usd).
Originally posted by philbaum Let me ask a dumb question here: What's the difference between moving the motor via the screw or:
A. Moving the motor by electronically exercising the focus when it starts to have warm up problems? (I think there is no difference in this case, but it needs the motor to continue moving and not be totally stuck)
B. Moving the manual focus adjustment ring? (i suspect that quick focus clutch could slip and not actually unstick the motor)
I think moving the screw head/back part of the motor does something different. It's not about moving the rotor/shaft. I think you're actually moving other parts of the motor.
If this indeed is some sort of utrasonic motor it is based on principles of friction with a piezoelectric material, my best guess regarding the fault os : 1. Maybe something sticks inside and need a nudge to get free or 2. perhaps its the other way around, that it gets too loose and the ultrasonic vibrations can't move the rotor. I'll have to read up on these kind of motors to know more.
Someone also asked if it could be that the mechanical autofocus link to the camera body also rotates when the SDM motor runs, and that the SDM motor doesn't have enough grunt to pull all that. It's an interesting thought. Maybe someone could try to remove the screwdrive af shaft from the lens? If the theory is correct you might even get slightly faster focusing because of less restistance/friction?