I don't know too much about Pentax AF motors. I think the MZ series all
have the same motor (except MZ-M). The PZ-1p's motor is significantly
stronger than the MZ motor. As for adding teleconverters and extension
tubes, yes that should increase the stress due to extra mass of the
coupling and friction in the adaptor - though if the adaptor is well
desighned and working properly the added strain would be minimal, I
imagine. An exception would be the Pentax 1.7x AF adaptor, where the AF
motor only moves the elements in the adaptor, and not the lens itself,
which is probably a lot easier than focusing a long, heavy lens.
As for motor failings, I think I have heard of them on the list, IIRC they
were all MZ-5's and ZX-5's.
Todd
At 11:32 PM 4/19/01 -0300, you wrote:
>Todd wrote:
>>
>> I would think so. I would also think that motors in the camera may fail
>> sooner if large heavy lenses are used a lot, as then the likely
>> underpowered motor will have to work harder, trying to do the job of a
>> larger motor.
>>
>> Todd
>
>That's exactly what I think about it.
>Do you know anything concerning Pentax AF motors? I mean, if they can be
>considered rugged enough to stand some larger lenses. Have you heard of any
>AF motor failure that can be attributed to the extensive use of large
>lenses?
>I can't help but think that, despite being used all the time, unlike AF
>motors mounted directly into lenses, the body mounted AF motor can benefit
>from a larger physical space provided by the body itself.
>Another point is the use of teleconverters and extension tubes that are AF
>compatible. Due to the adding of couplings, the stress on the motor would
>also be increased. Do you agree? Correct me if I'm wrong, but I think the AF
>works just like a car transmission or a prop shaft. If you add couplings,
>there will be a loss in power reaching its end.
>
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