TheSkySearchers

Fantastic set-up Henk. Time to collect some photons.

Go big or go home! Congrats Henk! Waiting for the first images from the beast.

yobbo89 wrote: ↑Sun Mar 14, 2021 12:54 pm diy spring loaded worm, custom motor/driverboard ?

Yes the spring loaded worms and look of the OnStep controller definitely have my signature on it, lol. It's fun to go the cheapskate route and add DIY features but of course this adds more to be debugged.

The spring loaded worms are something that comes standard with Losmandy mounts now. I did not want to send my mount back so I DIY-ed it in my own way. The outer bottom screw is loose so the sheet metal clamp pushes the worm in, and the spring pushes the worm tangentially. This is what users would do when adjusting the worm manually except it is now done constantly without tightening the screws. It fixed the binding issues that I had, which were a major PITA beyond my own fault (unless you believe that a mount should be sloppy and counterweighted).

The OnStep controller is a very simple one, it just takes care of the motors and Bluetooth (cell phone for a hand controller) none of the extra stuff. I let Ekos add the high level features such as setting the time/location, alignment plate solving, guiding, planetarium control, etcetera. It works very well IMHO. Mine have TMC2130 stepper driver boards with mode switching. I have yet to find out if this system limits the resolution. This scope will let me find out pretty quick what the issues are, if any.

After all this chatter the fearful moment arrived where I should show some results. I’m pleased with what I got given the circumstances:

- I had not checked the collimation since Agena Astro said they did it (it was probably OK)
- I did not put my Paracorr 2 CC on it yet, while the image clearly needed it at F/4
- It was rather windy and not super clear, somewhat humid higher up I think
- I had to get the new Pi 4B configured and hooked up
- I was working with my trusted Fuji X-a1 that I cannot control from Ekos (no gPhoto support)
- Aligning the guider with my camera was therefore a pain
- Astroberry did not pre-install the index files so only the online astro.net worked

The stats are

- Fuji X-a1 @ 6400 ISO, G11S, OnStep, Ekos, DSS, Gimp
- 87x58 s lights, 15 flats

Unfortunate side effects:

- Huge gradients that I had to remove. What’s up with my camera or the OTA or the new LED street lights?
- Blurry stars since the guiding had a total RMS of 2” to 3” (!! ugh it did not even fit on the scale)

If I had PI I could probably fix the stars or alternatively, remove them with Starnet++ then add them back in from a less stretched version so they are smaller. But this is a first light so I did not bother.
Here’s the DSS version where you can see the gradient:
The jump in this image is because I re-centered after the first couple of shots. Here you can see the coma very clearly so the Paracorr 2 will be on it the next time, assuming I have all the right adapters and it fits.

You can also see the fat stars. Some of it is due to the wind, no doubt. But I never fully debugged this in Ekos. What I may do tonight is just run the autoguider by itself – no scope. Then test all the autoguiders included in Ekos: The native one, PHD2 and lin_guider. I could not find any adjustments for the internal guider other than the size of the box. The other two have several parameters so I will play around with them tonight. Hopefully this is not due to the OnStep controller (stepper motors, driver boards) or the G11S with the DIY spring loaded worms.

I will also insert the Pi 4B on the board where the Pi 2B sits now. I will keep the Pi 2B handy just in case it turns out that the Pi 4B uses too much power for field use. Swapping them should be easy.

Plenty of things to try and improve on. Anyway this was the first light, I have some work to do and will continue in other threads once things are dialed in.

PS: One thing I just noticed - I never tightened the Az screws after PA. That makes the mount looser than it should be especially when slewing.

Other then the rms, not bad on the guiding,seems to be going back on track,round stars ect. Some psf ,deconvolution should definitely tighten up those stars. Maybe some tuning on the guiding exp time and pulse settings ?

yobbo89 wrote: ↑Mon Mar 15, 2021 6:47 am Other then the rms, not bad on the guiding,seems to be going back on track,round stars ect. Some psf ,deconvolution should definitely tighten up those stars. Maybe some tuning on the guiding exp time and pulse settings ?

Thanks Rob. I see several options that I want explore running with just a guide scope, no OTA. First off I focused my guide scope once not quite focused as I heard that that would benefit guiding. I want to see what happens when I focus it. Most of my guiding has been initially with PHD, then with lin_guider on Pi, sometimes PHD2. Now I'm using the Ekos guider. I want to compare them. I expect them to be pretty close when tuned well. With just a guide scope I should be able to reach 0.5" total RMS. If not, then I have to look at the hardware. How much is it affected by the pulse rate of the stepper motors, are my spring loaded worms working as expected or is there play or stiction, is the aging QHY5 good enough, etcetera. Once that is resolved I need to add increasing loads and see what happens. Lots to figure out and I need to get to the bottom of it.