Old 08-09-2018, 08:45 AM
Startrek (Martin)
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Join Date: Dec 2017
Location: Sydney
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Guidescope focus

Just some feedback on my method of focusing my guide scope
It’s an Orion 50mm mini guidescope with helical focuser and my guide camera is ZWO ASI 120MM. Scope is a 6” f6 newt
I remove the camera,install my Orion 20mm illuminated reticle eye piece, slew to a star ( say Altair) centre it , adjust focus using the ring/ wheel, slew to my target say the Lagoon nebula, centre it , remove eye piece , install my guide camera , connect to PHD2

Question: is focus based on your eye sight through an eye piece good enough for the ZWO ASI 120MM camera to lock onto a guide star

I have read and seen on YouTube clips etc....that you are better off having your guide camera slightly “out of focus” for successful calibration and subsequent guiding

Appreciate some advice and comments

Thanks in advance
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Old 08-09-2018, 09:02 AM
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Join Date: Sep 2005
Location: Newcastle, Australia
Posts: 2,414
I would just have the CCD in the scope, slew to a 'busy' field - like into the middle of the Milky Way, and start PHD2 looping - now rack the focuser of the guide scope until the stars are focused on screen.

I don't know about the 'slightly out of focus' mantra.... just lock PHD onto a non-saturated star.

To do the eyepiece switcheroo you would first need to ascertain where the EP and CCD are parfocal....
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