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Old 05-09-2011, 11:50 AM
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alistairsam
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Location: Box Hill North, Vic
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Quote:
Originally Posted by bojan View Post
Shaft end I meant.. because average camera scale will be close to 1 arcsec/pixel (1m FL, 5um pixel).

I am aware of those closed-loop systems, but they must be extremely expensive (encoder must be free of PE and backlash, which is not possible to achieve (at reasonable price) with up-gearing)- so I don't think they will ever be available for average user.
And what's the point? Guiding works well (not my own experience yet, though).
Bojan, still a bit unclear. you mentioned 1arc sec at RA shaft end. so what would the resolution of encoder be for 1arc second?
wouldnt it be 86400 for RA (in time increments) and 1,296,000 in Dec for 1 arc sec?
i read somewhere that the losmandy mounts have a resolution of 1/2 arc sec based on the encoders on motor shaft and subsequent gear reduction which is quite high as they use servo motors in a closed loop.
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