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Crayford focuser vs Rack and Pinion

AndyExton

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AndyExton

AndyExton

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I have a skywatcher 8" skyliner dob and a shywatcher evostar 120. I have seen crayford focusers available for these models. Is it worth upgrading the standard focusers? What are the advantages / disadvantages of a crayford focuser as I know nothing about them?

Andy

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brianb

brianb

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The smoothness of action of a Crayford focuser compared with a cheap R&P is a good reason for upgrading, as is the lack of lateral slop in the focuser tube. However there's nothing wrong with rack & pinion in principle, when properly (and expensively) engineered they are fully the equal of a Crayford in smoothness & slop control, and have far less of a tendency to slip under load. The best focusers in the world are rack & pinion, & such devices are practically essential for automated (robotic) focusing as the slippage in a Crayford makes presetting focus positions next to impossible.

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ollypenrice

ollypenrice

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The smoothness of action of a Crayford focuser compared with a cheap R&P is a good reason for upgrading, as is the lack of lateral slop in the focuser tube. However there's nothing wrong with rack & pinion in principle, when properly (and expensively) engineered they are fully the equal of a Crayford in smoothness & slop control, and have far less of a tendency to slip under load. The best focusers in the world are rack & pinion, & such devices are practically essential for automated (robotic) focusing as the slippage in a Crayford makes presetting focus positions next to impossible.

The perfect answer!

Olly

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