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NGC 1499 Work in Progress and DIY "Polemaster" with Ekos Alignment Module

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So far, I have roughly 2-2.5 hours on Ha on each panel after one night. I'm quite happy with the results on such limited data. Perhaps really good seeing conditions help? So how do you know when enough Hydrogen Alpha data is enough? I plan on adding RGB data to this. Not sure about Luminance at this point. Maybe use the Ha data as a luminance? On this target, is HaLRGB preferred or is HaRGB okay? Acquisition details on the linked website. Let me know what you think. Thanks for looking!

Also, I attached a picture of my "DIY Polemaster" which I used with the Ekos Alignment Module. It's an ASI120MM-S (I also use for guiding), an $8 25mm lens and a used pole master adapter. Total cost was $30 not including the camera I already had. FOV is about 11X8 degrees. I got way more consistent Polar Align error readings with this rather than using the main scope (420mm FL refractor). According to ekos my polar error was 0.48" when I was complete and I couldn't really see the error on the vector since the FOV was so large. I didn't have a chance to really test how good PA was with PHD but all the subs were 10 minutes so I guess it got close enough!

Wes

astrob.in/385901/0/

5 years 2 months ago #33687
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This is smart! I am going to try this with a 50mm lens.
5 years 2 months ago #33821

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I was inspired to try this for myself so I designed and 3D printed a mounting system for my mount and Star Adventurer. I am now just waiting for delivery of the lens.
5 years 2 months ago #33846

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I tried this thing earlier with 25mm lens and Kowa 75mm lens ..

Last edit: 5 years 2 months ago by Tarun.
5 years 2 months ago #33852
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So I've had the chance to test this DIY Polemaster out with the Ekos Polar Align Module a couple of times now and although I get very consistent readings, I get way better polar alignment by using the polar scope on the mount. Every night, I align using the polar scope (which is calibrated and not far off). I've checked PA error with PHD in the past and I'm always close but of course not within 1'. After aligning with the scope, I use the PA module in Ekos with my DIY polemaster (ASI120MM-S and a 50mm lens). Ekos always says I'm out of alignment by about 6-7'. It's always the same direction. I adjusted the mount the way Ekos wants until it's satisfied within 1'. I looked through the polar scope just to see how far I moved it and I feel somethings not right, it's just too far off. I've checked the result using PHD and sure enough, the PA error with Ekos alignment is very noticeably larger than with using the polar scope alignment. According to PHD the error with Ekos alignment was around 7-8' and the polar scope alignment according to PHD was around 2-3'. I gotta say Ekos is consistent but for some reason it's getting the North Celestial Pole position wrong for some reason. I've tried switching atmospheric refraction on/off, I've tried double checking the location and time and it always off by the same amount. Obviously with this setup, I've eliminated the possibility of errors with the DEC motor moving and RA axis/camera lens not being aligned. It's definitely not a technical issue, it's something with the way Ekos is determining the NCP location. I'd like to take a screenshot next time of the Ekos PA vector so we can see where it thinks the NCP is and see if it's indeed in the correct spot. Any ideas or suggestions are appreciated. I'd really like to get this fixed if we can so other people can use this technique to Polar Align.
5 years 1 month ago #35021
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I aspire to be educable: How does the mechanical setup eliminate the possibility of misalignment between the camera and the RA axis? I mean, it *looks* like it should be dead on. But...back face of adapter not orthogonal to axis? Axis not exactly aligned with the polar-scope sleeve in the mount? (Some polar scopes adjust within that mounting, after all.) We're talking about pretty minute angles, here.

Not asserting, just asking. Now you've got me really fired up to try the same thing with my 120MC and CEM25P.
5 years 1 month ago #35024

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It's the same mechanical assembly as used in QHY's polemaster. It should be pretty dang close to being aligned to the RA axis but maybe not? IDK. Has anyone had a similar issue with the ekos PA module? It always consistently putting me 7-8' arcminutes out of alignment for some reason. The good news is that it's consistent but obviously, it would be nice if we can get it closer to 1'.

So, what if I adjusted the polemaster mounting bracket so that when Ekos throws the RA axis vector on the image, the RA axis is exactly dead center of the image? Last time I used it, I noticed it wasn't exactly dead center but it was fairly close. (Maybe 7-8' arc minutes?!) There is some room to adjust it since it's assembled to the camera with only one screw (the center screw on the back of the camera). Is that worth a shot or should it even matter at all.
5 years 1 month ago #35025

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It doesn’t matter if the RA axis is dead center or not. I use the pa module all the time with my HEQ5 mount and I use my imaging telescope and camera. They certainly don’t have the RA axis dead center nor do they point exactly at the pole and still I get sub-arcminute alignments.
5 years 1 month ago #35030

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Maybe you need better cable management. The way they hang off everything in your picture could be pulling things askew as you make your rotations.

Edit: apologies. I was looking at tkottary's image.
Last edit: 5 years 1 month ago by Andrew.
5 years 1 month ago #35031

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Oh, of course. Apologies. Spatial visualization is not my strong suit -- I depend on my wife for all the geometric thinking. And yes, I am aware that men average better at that than women. We're both outliers, it seems, just in opposite directions.

I am really interested in trying this -- it's just so appealing to bung the adapter into the end of the polar-scope hole and Bob's your uncle. OTOH I'd be running exactly the same procedure in software, so maybe I'm better off just leaving the 120 on the guidescope in the first place.
Last edit: 5 years 1 month ago by Rick Wayne.
5 years 1 month ago #35056

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I am wondering whether this might be an iOptron driver problem. I have a similar issue with my iOptron SmartEQPro+. My Atlas Pro mount, by contrast, aligns just fine using the EQMOD driver.
5 years 1 month ago #35065

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There were reports that Ekos PA tool would advise you to go in the opposite direction. So try this, use Ekos PA again, but this time, go completely in the opposite direction, does this help at all?

If this somehow ends up working, we need to figure out what makes your situation different as I have no idea what leads to this.
The following user(s) said Thank You: Wes Creech
5 years 1 month ago #35072

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