Just to make sure, did you create a new profile in PHD2 with a guide focal length of 2000??? If not, then PHD2 still thinks your guide scope is 600 mm when it calculates your error in arc-sec. It could be overstating your error.?? I assume you've also re-run your calibration as well, right?? Chances are you've already done both these things, but I just wanted to make sure.?? I also am ready to switch from a 60mm guidescope to an OAG, but have been reluctant to do so since the guidescope has been working very well for me lately.? I'd love to hear what the remedy winds up being.
Best of luck to you,
-Tony
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On 9/23/2021 2:35 PM, Magnus Larsson wrote:
Hi!
Maybe you in this group can help me understand this:
I'm using a G11 with a C11. I've been guiding with a guidescope for a long time, getting between 0.4 (on very good nights) and 0.9" in RMS, typically around 0.6-0.7".
Now I am trying with an OAG. And now I rarely get below 1". I was expecting better, not worse guiding.
My guidescop is f= 600 mm, on my C11 I have 2000 mm focal length. So I am far more "exposed" to scintillation and seeing effects with the OAG. But is that what this is all about - so that my worse guding is not in fact worse at all.....? I find that my guiding curves (the graph in PHD2) shows what I would call irregular patterns in both DEC and RA, rather than for instance, stable DEC with a slow drift (caused by the PA error), and RA "chatter" caused by variuos PE frequencies. THis makes me think I am chasing seeing. However, increasing the exposure time to 3 sec or higher only results in wors guiding. Best results so far is with 1 sec exposure.
I have an Atik OAG and a ZMW Asi 174 camera in it.
And: images are good. Not worse than before at least... But the patterns I see would not result in elongaged stars but "only" higher FWHM, as I understand it.
Any ideas on this? What are your experiences from using OAGs?
Magnus
