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DIY focuser on SCT - SOLVED thanks


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I'm not sure if this is a hardware or software question so I have put it here.  In the New Year I'm hoping to make the Arduino stepper motor focuser ( https://sourceforge.net/projects/arduinofocuscontrollerpro/).  The pdf instructions raise the issue of backlash in the SCT focus knob.  Two solutions are given, add a Crayford focuser or use FocusMax which only focuses in one direction.  Both those involve spending more money than I really want to and ignoring the cost may not be feasible.

So a couple of questions:

1) Can I add a Crayford focuser when I am using a focal reducer?  If so what does that do to all the careful setting up required to get the OTA and OAG cameras working together?

2) Does SGPro work the same way as FocusMax (i.e. focus in one direction only)?

Actually I don't understand how FocusMax works in one direction only.  It seems to produce a V-curve to find the optimum focus point (as SGPro does) so presumably it will have to wind back to the best position after producing the curve, thus encountering backlash.


Edited by rubecula
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First of all yes you can use a crayford focuser with a focal reducer, I do it all the time works perfectly, I use the original focus knob for coarse focus, then me motorised crayford for fine focus. You just need to still get the same correct reducer to chip distance as before when using a reducer....

not sure on the software as I don't use SGP I use APT as my image capture software....

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