08/18/2023 – A Mostly Clear Night to Test Out the UA Field Flattener

It has been a pretty good while, most of the summer, since the Suffolk Sky has seen a clear night on a night that was not a school night. The forecast looked decent for this Friday night, so I got everything set up, cabled up, balanced, and ready to collect some light. I was looking forward to trying out the new Universal Astro Adjustable Field Flattener I picked up from Astronomics a few weeks ago.

Back on the SV503 102ED with the ZWO ASI294MC Pro for this and upcoming sessions. I have had some fun with the C8 but the SV503 is a bit better suited for the nebulas and open clusters currently filling the night sky.

The goal for this session was really just to make sure everything worked ok (since it has been a bit since the scope has collected any light) and to test out the UA Flattener. Cabled everything up to the Libre SBC, started the INDI Server drivers, and connected up the gear through Ekos, no issues at all.

The image train with the UA field flattener is: the Camera, an 11 mm spacer, a 16.5 mm space, the UA field flattener, and a 2″ nose piece into the SV503. The picture is not the best but hopefully you can make out the configuration.
UA Universal Flattener for Refractors
I started with 55 mm of spacing between the field flattener and the camera, but I was not able to focus in that configuration. After a bit of tinkering the spacing above is what seemed to work. I have the adjustment on the field flattener set to 3 ticks out from 55.

The Ekos Focus Module settled the ZWO EAF on 7814 steps to get the star field into pretty good focus. After getting focus plate solving was calculating the focal length at 699.6 mm, this is only 2.4 mm off the actual focal length of 702 mm, not sure I could get it much closer. The focal ratio is calculated at F/6.9.

With decent focus and plate solving working I decided to have a quick go at NGC 7635, the Bubble Nebula, in the constellation of Cassiopeia. This is a 10 minute EAA live stack of 20 x 30 second exposures at 121 gain, 30 offset, and bin 2×2.
NGC 7635, The Bubble Nebula, EAA Capture 08/18/2023
The Bubble Nebula looks great, nice color, great stars. Messier 52 (M52) is the open cluster in the upper right. There are no flats or darks, I am using SharpCap’s remove hot pixels feature to clean up the stack a little but there are still some hot pixels. Going to get some darks and flats for the next session.

Looks pretty nice over all. Field is pretty flat out all the way to the corners, maybe just a slight bit of stretch but I think I have the spacing for the field flattener just about right.

I covered the scope at around 10:30 PM. I should have stayed up longer but Saturday is going to be a great day with the grandkids. Saturdays forecast looks very promising, so hoping for clear skies and to get out to gather a bit more light.

Looking forward to some more clear skies…

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