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I always thought the big benefit of direct drive is no backlash/friction etc.
DEC would certainly benefit from No backlash,
but without the HiPrec encoder it is ( relatively ) useless for absolute precision/tracking at the arcsec level.
In RA, i would think that ( as the motor doesnt need to reverse ), tracking would merely be a function of the speed of the encoder/motor feedback loop and the accuracy of the encoder itself, incl any reading artifacts.
There has been a very good ( long ) thread on CN recently re the new encoder put out by IOptron for the CEM mount.
The technical/mechanical problems associated with the encoder itself ( when looking at the arcsec level ) shows that a lot of the real gains/losses can come from the encoder itself, vs the drive mechanism.
Very interesting as a system integration exercise.
Andrew
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