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Old 24-01-2010, 04:32 PM
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multiweb (Marc)
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Join Date: Oct 2007
Location: Hinchinbrook
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Originally Posted by koputai View Post

What should the relationship between the focal lengths of your imaging scope and your guidescope be? If imaging with an ED80 (600mm), would 150mm be ok for the guider? What about the converse, if imaging with a 150mm lens, does the 600mm of the ED80 make for good guiding?

This is what I've observed. In my experience (I guide with PHD) it doesn't matter. I guided a 5"newt at F/5 with and ED80. Similar image scale. I guided a C11 at F/10 with an OAG and with a finder 8x50mm. PHD can detect the motion of a fraction of a pixel in your guider. Changing the guider image scale didn't make the slightest difference IMO and having more pixels in your stars on the guider is not going to make you mount react faster or go from A to B any better.
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