Olympus M.ZUIKO DIGITAL 12-50mm Zoom Resolution

I'm controlling the Olympus M.ZUIKO Digital 12-50mm 1:3,5-6,3 with the Arduino Shield.

I found, that the entire Zoom range cannot be positioned in more than 240 steps. Although the "set absolute zoom position (normalized) .8" instruction allows 2048 different positions from 0.0 to 1.0 fixed16, the zoom motor doesn't move for 8 consecutive positions then does a big step to the next position This implies to me that the lens uses only an 8-bit D/A converter (256 positions) for positioning the Zoom. Moving from one position to the next is a "big" visible step to the eye. It is not possible to achieve a smooth zoom function at low zoom speeds, because the zoom will move in steps.

I think the "set continuous zoom (speed) .9" command does not allow slow speeds for the same reason. Even a speed of 0.001 moves rather fast (about half the speed of maximum +1.0) to avoid seeing the steps. A smooth zoom movement can be achieved only, when consecutive positions sent to the lens D/A converter are increasing faster than the physical motor can follow.

If anybody has more insight to the lens behaviour it could help me, I need to control the zoom in my project smoothly with low and high speeds and don't see a possibility to achieve it.

Also the Olympus M.Zuiko Digital ED 14-42 mm EZ-M1442 cannot position zoom smoothly.

Bernhard

This may be from left field, pardon me if it's not relevant to your lens.

The small cameras I have disassembled in recent years had stepper motors to control zoom,
not servo motors or some two wire motor that could be controlled by a DAC with some kind of
position feedback mechanism. 240 sounds like a reasonable number of steps for a stepper motor.
If you have steppers, you obviously cannot get continuous zooming, no matter what your software
supports.

However, the Olympus specs for your lens mention "linear motor control" for focusing.
You might try contacting Olympus to get more info about the zooming capabilities of the lens.

Also you should mention what arduino shield you are using, which arduino board and what software
it is running.