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Hi Everyone, I just recently installed a ZWO OAG/ASI220mm mini on my Explore Scientific ED102 (reduced to 571mm). I switched to an oag from a Orion 50mm guide scope and Orion SSAG.Before installing the oag, I have been having guiding issues and I submitted a post to the PHD2 Forum. The PHD2 Forum has always been extremely helpful and my response was that I had too high of an image scale with the Orion setup (6.6 arcsec/px) especially with my light polluted skies and very poor seeing. I was recommended to go with a longer fl guide scope or an oag. I really didn’t want to add more weight to my setup (15.6 lbs with the Orion guide scope/camera setup), and I am using an HEQ5 mount, so I decided to try an oag.Setup went well. I have 55mm of back focus from the FF/FR to the main imaging camera sensor (ASI533MCP) and from the FF/FR to the sensor of the guide camera (ASI220mm mini). I rough focused during the day using Sharpcap on my most distant object (a communications tower about ¾ mile away). All looked good. Just to make sure that PHD2 could see an image, I covered the scope objective with aluminum foil and poked a hole in the center (to reduce light). I set PHD2 on a very short exposure and I saw the tower on the PHD2 imaging window in focus. That night, I created a new profile for the oag in PHD2 and calibrated PHD2 (went well). Without moving the scope, fine tuned the focus which was already very close.I ran the PHD2 GA and accepted the recommendations and started guiding. Note the repetitive star patterns.  I was running things from my desktop pc indoors (RD) and everything looked great.When I stepped back from the monitor, I noticed that the PHD2 imaging window looked like it was made up of four duplicated images. Upon closer inspection, all four “panels” looked like they all had the same exact star patterns. PHD2 auto selected a single guide star and the guiding numbers were great (too great) at 0.2-0.3 arcsec total rms error. This is the only image that I captured where you can see the four image "panels". You can barely see a dark border crisscrossing the image window below. Note that the stars are four mirror images of one another.  PHD2 looked like it was guiding on a star a not a hot pixel because the graph had RA/DEC movement and was issuing corrections to the mount and it looked like the mount was responding. See guide log image below. Another screen capture during guiding where the duplicated star images are apparent. Unfortunately, I turned down the gamma slider and the image panel borders are much less obvious, but the same star patterns can bee seen. I took some test images of M44 and M81 (different parts of the sky) and the rms error was similar (very low).Some star eccentricity, (RA rms error was more than DEC) which didn’t surprise me, and it compared to other subs that I have captured with the guide scope setup. Actually, maybe a bit better with the oag. I submitted the logs to the PHD2 forum along with images of the duplicated image windows (four “panels” in the image window) and they responded that possibly what was causing the duplicated “panels” in the PHD2 image Iwas caused by internal reflections from the very bright moon. Also to note, I did not see four “panels” or replicates of the tower that I tested focus on (with the foil). Also, I aimed the scope at the ceiling inside the house and looked at the PHD2 screen (of course, way out of focus) and saw only one image panel. The PHD2 folks are wonderful and have seen almost everything. They have been very helpful to me. I do wonder about internal reflections from the bright moon though since I did see the four image “panels” when imaging M81 that was not located anywhere near the bright moon. A helpful fellow on the Cloudy Nights Forum asked me if I was using the native ZWO camera driver for ZWO ASI cameras in the Connect Equipment window of PHD2 and I checked and found that I was using the ASI (ASCOM) driver. He mentioned that he had issues using the ASCOM driver and recommended the native ZWO driver for the 220mm mini. My current plan is to create a new profile in PHD2 using the native ZWO camera driver and test it on the next clear night which might happen sometime this week. Of course, the moon will still be a big influence, but when the scope is pointed over 90 degrees away, the internal reflections from the bright moon should not be an influence. Has anyone seen anything like this before? I sure hope that someone has seen this issue or something similar and can offer some suggestions. Thanks for any help or suggestions! EDIT: I did try changing the usb cable to the guide camera. |
