NGC6820 in SHO with Quattro 250.

[Tommohawk]

My Quattro has been out of action for a while cos I borrowed the mirror for a project but I've just reassembled and collimated it and needed to test it out. I've not done much with it cos I only have an HEQ5 - I did one session previously unguided with mixed results. So just for a laugh I put the Quattro on my ADM dual mount with 60mm guidescope - and all the weights I own. It was still pretty top heavy and main risk is if the RA clutch slips, gravity will spin it round and do some damage. So I was extra careful!

Discovered this target quite by chance - I wanted to do the pillars in Eagle but it's too low and obstructed by houses. NGC6820 has similar gas pillar features, and is a similar distance at 6000 ly.

The main issue (there is always something!) on this target, which I did over 4 nights from 12th June, was that NINA seemed to stop part way through each run. After night #2 I figured out it was stopping on filter changes which it never used to do. Short version is that I allocate a target for each filter run (yes I know that's weird) and turns out with the latest version of NINA you need to enable "start guiding" for each target. Seems odd, but there you go.

So unfortunately only a limited number of subs - plus it was full moon, and one night was windy, and one night I had lots of what I can only assume was thermal distortion - astigmatic looking stars in one corner. Collimation was still fine. 

Anyhow - guiding was mostly impossibly good, apart from the windy night, at around 0.75" arcsec -  at least that's what was reported.  The other odd thing is that the standard Skywatcher 0.9 coma corrector appeared to work fine - -which is peculiar because when I tried it before at F4 it seemed poor. Another mystery.

So - Quattro 10 with  SW CC giving F3.6, ASI1600 cool, NINA, Astro Pixel Processor including star reducer, quite a bit of PS, cropped and rotated 90 deg CCW. About 75 Ha, and 60 OIII and SII all at 180secs, gain 300. Some funny stars, and a bit noisy but pretty good overall. And let's here it for the HEQ5! Hope you like it - grateful for any any comments 

 

[carastro]

Can’t see the pictures Tom.  The boxes ate there but no picture in them. 
i am looking on the phone though. 
 

Carole

[wimvb]

That ’s a heavy weight to lift for that mount. But the result looks great. (Pictures show alright.)

[Craig a]

That’s A decent image, maybe abit too heavy for the heq5 but it looks like it coped with it, one thing I would do though is change that green vixen bar for a losmandy plate, I too own the Quattro 250 but the carbon fibre version, not sure why skywatcher don’t supply a bigger newt with a losmandy bar a vixen just doesn’t cut it in my opinion. Also I fitted an extra tube ring next to the focuser, that does two things, abit of extra weight top end meaning you can slide the tube down the two main rings spreading the weight more equally instead of having almost half the tube unsupported and it helps stiffen the tube around the focuser reducing any flex from the weight of the camera, f4 is very unforgiving to any flex in the system, I’m not criticising you in any way just giving you some pointers to help improve the scope and get it performing something close to spec, another tip if you can is go down the OAG route for guiding a big Newtonian really shouldn’t use a separate guidescope there’s too much flex in that too, I battled funny stars for ages but phd saying all was good, changed to OAG and it was fixed, too much differential flexure between the guidescope and main scope was the cause 

Edited June 27, 2022 by Craig a

[Tommohawk]

12 hours ago, carastro said:

Can’t see the pictures Tom.  The boxes ate there but no picture in them. 
i am looking on the phone though. 
 

Carole

Hi Carole - not sure why that is. I can see on my phone and PC, and looks like others can. Something funny with your phone download maybe? 

PS I'm still fighting with my Dark Shark... and losing!

[Tommohawk]

11 hours ago, wimvb said:

That ’s a heavy weight to lift for that mount. But the result looks great. (Pictures show alright.)

Thanks Wim.

I haven't added up the weight exactly but it's 20kg give or take - not bad given the max payload for imaging is usually given as about 11Kg. TBH the guiding is as pretty much as good as any of my other lighter setups - but it's too risky. If the RA clutch slips it could be expensive!!

The Quattro will go up for sale I think - I really only did this to check it's collimated OK and give a prospective buyer some idea of what it can do.

2 hours ago, Craig a said:

That’s A decent image, maybe abit too heavy for the heq5 but it looks like it coped with it, one thing I would do though is change that green vixen bar for a losmandy plate, I too own the Quattro 250 but the carbon fibre version, not sure why skywatcher don’t supply a bigger newt with a losmandy bar a vixen just doesn’t cut it in my opinion. Also I fitted an extra tube ring next to the focuser, that does two things, abit of extra weight top end meaning you can slide the tube down the two main rings spreading the weight more equally instead of having almost half the tube unsupported and it helps stiffen the tube around the focuser reducing any flex from the weight of the camera, f4 is very unforgiving to any flex in the system, I’m not criticising you in any way just giving you some pointers to help improve the scope and get it performing something close to spec, another tip if you can is go down the OAG route for guiding a big Newtonian really shouldn’t use a separate guidescope there’s too much flex in that too, I battled funny stars for ages but phd saying all was good, changed to OAG and it was fixed, too much differential flexure between the guidescope and main scope was the cause 

Thanks for that Craig. 

Agree about the Losmandy plate, although the mating face of the SW scope ring isn't really wide enough to take full advantage of the Losmandy bar. The ADM mount and guidescope are rock solid but there must be some flex in the imaging scope. The stars are a bit eggy for sure - star reduction helps with this, but there must be some loss in detail overall. 

I've never worked with an OAG, although I know they seem to be favoured.  My imaging setups vary a lot and some are very short so an OAG may be problematic. I find it easier to just use the same guide scope for all on the dual mount - but some compromises for sure.

Edited June 27, 2022 by Tommohawk

[carastro]

19 minutes ago, Tommohawk said:

I'm still fighting with my Dark Shark... and losing!

Oh dear that's a shame.

I can see your pictures today on my laptop.  NGC6820 is excellent, lots of lovely Oiii which I failed to capture (not for the want of trying) at Cairds.  Lovely processing.  Only one possible comment, I wonder whether it is a bit too smooth, did you do some noise reduction on it?  Might do with a little sharpening to the edges of detail perhaps.  

Carole 

[Tommohawk]

Thanks for your kind comments Carole!

The main issue I had with this, particularly the OIII, was sorting the gradients, especially as there was a full moon. Astropixel processor worked well for this, but only when processing as separate mono images and combining in PS. APP didn't do a good job at all when working in RGB (SHO)t 

Yes I did 2 rounds of noise reduction, which isn't ideal, but when viewed at 100% it's pretty grainy otherwise. I did try some selective sharpening but again at 100% it looked a bit nasty. Of course we often don't view at 100% so maybe I could get away with it.