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Meade ETX125 and Orion Autoguider

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:(Has anyone attempted to use an Orion Starshoot Autoguider /PhD software with a Meade ETX125 and Autostar controller? When I attempt this, the calibration phase completes successfully, but after a few minutes the guiding sequence breaks down. Low S/N ratio is blamed, but I select fairly bright guided-stars and 2 sec exposures. It has been suggested to me that the Orion autoguider is not compatible with Autostar. Has anyone had similar experiences, which they have managed to overcome?

Thanks, Herrman

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i have been told though i don't know the reasons that SCT typed telescopes are not good for guiding?

how is the S/N level of the guide stars? i find that dew and thin cloud passing over head don't stop the guiding but then i have a 80mm scope at f/5 which means i have a large FOV to look for bright guide stars, and i never go above 2.5sec?

just a thought....

if you are guiding at f/10 then your FOV compared to mine is (5*5)/(10*10) = 4, 4 times smaller but the stars in it are (125*125)/(80*80) = 2.5 times bright than mine. you get a quarter of the stars i have but yours are 2.5 times brighter.

this means if we assum a even distribution of stars that you have only got 62% of the usable stars i have. (not helpful :) )

mmm if the orion autoguider is not compatible then what is? it is just an ordinary ST-4 typed output?

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Hi All,

Many thanks for your thoughts and suggestions.

I started at the bottom of the curve when using the autoguider. Initially, I was interested to see how well then guider worked without doing any imaging, so I centred on a 1st mag star and hit the button. When that didn't work well I dropped down to 2nd mag stars. I also experimented with a range of gain and exposure settings, but always ended up with losing the guide star and getting the low S/N ratio report. I hadn't thought about the mirror, but there appeared to be no shift in the image on the laptop screen- apart the stars disappearing off the edge as the guide was lost. The skies were light polluted, but clear, and the corrector plate was dew-free. I can think of no reason why the autoguider/PhD shouldn't work with the ETX, but then I am no electronics/software wizard. I did wonder if drive slip was to blame.

Has anyone tried using any other SCT model for autoguiding?

Thanks again for your suggestions, they are appreciated.

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