qhy22 first test image help me troubleshoot star shapes and a few other questions

[rustigsmed (Russell)]

Hi all,

took delivery of a new qhy22 (thanks Theo!) recently and haven't been able to get out because of bad weather. this is my first ccd, moving up from dslr so I know its going to take a while to get it all up and running to how i'd like it to.

I have ezcap the qhy software and have a trial version of SGpro. I found myself polar aligning and focusing with ezcap (couldn't find liveview on sgpro I also couldn't get SGPro to connect with my moonlite focuser (maybe that's why I couldn't see a live view function). not sure how i'll remedy that yet - open to suggestions. saying all that I struggled getting a good polar alignment (maybe because I was tired and rushed) however it felt like I could have done it 3x quicker with the realtime live view of a dslr. but I can get used to that.

In SGpro and software is the temperature readout eg -30deg C actually -30 or is it minus 30 degrees of what the sensor was at? the qhy22 is able to go -45 so i'm not sure what figure I should be plugging into the temp control.

I have this on a newt with an OAG. I hadn't really sorted out exact parts but thought I would be pretty close to correct spacing with existing parts if I used my MPCC. to reach focus however I had to put it in a crappy extension tubethingy (single screw tightened - no ring).

anyway I've linked to two test shots. the star shapes a fairly crazy in both images. one is a 5min bin2x2 and the other is a 15min 1x1 Ha in 97% moon. no flats or darks - quick and nasty stretch to show the stars.

My guess is a combination of incorrect spacing for the coma corrector and perhaps tilt from the extension tube mechanism (and perhaps softish focus) but interested to hear other peoples thoughts if they think its a correct hypothesis? I think I will move back to the RCCi but will need to find an m48 extension of about 36.5mm I think (to account for the sensor to front of camera distance difference between DSLR and qhy22 ... 44mm-7.5mm). that will push the camera back to a position that the focuser can handle without a third party extension tube also.

15min 1x1 Ha
https://www.flickr.com/photos/803366...blic/lightbox/

5min 2x2 Ha (actually 4x4bin 1 min)
https://www.flickr.com/photos/803366...blic/lightbox/


edit: whoops that 2x2 bin version above was actually a 4x4 bin

here is 5min 2x2
https://www.flickr.com/photos/803366...blic/lightbox/

Thanks

Rusty

ps - pretty excited to get this camera up and running, despite the wonky image I can already appreciate the resolution and lack of noise over a dslr

[glend (Glen)]

There are two dark thin horizontal lines near the bottom in the 5 min shot. I'd be more worried about those than the star shape at this point. They don't appear in the 15min shot. Strange?

[rustigsmed (Russell)]

Originally Posted by glend

There are two dark thin horizontal lines near the bottom in the 5 min shot. I'd be more worried about those than the star shape at this point. They don't appear in the 15min shot. Strange?

hi glen, yes I see those i'm not sure the cause, I am guessing it may be from binning - or perhaps interference? i'm not sure if it is cause for alarm yet, as you say the 15min 1x1 shot is pretty clean. but perhaps someone else with ccd experience could advise that would be great.

[Atmos (Colin)]

They could be binning artefacts, your best way to see would be to take a dozen or so bias' and stack them, see if they remain.

From the 1x1 it looks like you have done tilt. The smaller the pixels are the more readily they become observable (I think).

What is a QHY22 worth these days? I have been considering making the change from my QHY9 for the much larger QE in Ha (30% vs 60%).

[Shiraz (Ray)]

that is starting to look really promising Russ.

You know this stuff, but FWIW, the various faults might possibly be:
1. field rotation - see if the star elongation changes with exposure length.
2. collimation - did you collimate through the CC? - minor tilt in the CC elements can throw everything off and I found that collimating through the CC was essential.
3. image plane tilt - anything other than screw thread or flange extensions will be too sloppy to keep stuff aligned. If the image train is rigid and there is still some tilt, I think that the camera has a tilt adjustment ring? the SX website has a great procedure for adjusting CCD tilt using laser projection if you need to adjust the camera - should work fine with a QHY
4. flex - if that is one of the GSO steel tube scopes, it would be a good idea to reinforce it around the focuser.
5. CC spacing - has to be exact including any filters - there is nowhere for minor aberration to hide with small pixels

not seen anything like the row fault in the 2x2 image - could it be a jpeg compression artefact maybe. Maybe ask Theo for an opinion, but I would sort out the other stuff before worrying about that issue. Otherwise, the chip looks very clean.

[rustigsmed (Russell)]

Originally Posted by Atmos

They could be binning artefacts, your best way to see would be to take a dozen or so bias' and stack them, see if they remain.

From the 1x1 it looks like you have done tilt. The smaller the pixels are the more readily they become observable (I think).

What is a QHY22 worth these days? I have been considering making the change from my QHY9 for the much larger QE in Ha (30% vs 60%).

thanks Colin, I think you are right on the tilt - i'll definitely check bias too. have sent a PM for more details on the cost.

Originally Posted by Shiraz

that is starting to look really promising Russ.

You know this stuff, but FWIW, the various faults might possibly be:
1. field rotation - see if the star elongation changes with exposure length.
2. collimation - did you collimate through the CC? - minor tilt in the CC elements can throw everything off and I found that collimating through the CC was essential.
3. image plane tilt - anything other than screw thread or flange extensions will be too sloppy to keep stuff aligned. If the image train is rigid and there is still some tilt, I think that the camera has a tilt adjustment ring? the SX website has a great procedure for adjusting CCD tilt using laser projection if you need to adjust the camera - should work fine with a QHY
4. flex - if that is one of the GSO steel tube scopes, it would be a good idea to reinforce it around the focuser.
5. CC spacing - has to be exact including any filters - there is nowhere for minor aberration to hide with small pixels

not seen anything like the row fault in the 2x2 image - could it be a jpeg compression artefact maybe. Maybe ask Theo for an opinion, but I would sort out the other stuff before worrying about that issue. Otherwise, the chip looks very clean.

thanks for commenting Ray - yes if I can get everything working together reasonably well I should be able to punch out some half reasonable images - with the 12"f4, 694 chip combo. well actually the qhy22 is lighter than the old 600d (470grams vs 570) and I think has larger pixels too (4.54 vs 4.3)! definitely a much smaller fov which should make it image capture easier ... in theory atleast! if I had that result on a dslr it would be even more of a shocker! (the weight the depth of the qhy22 does possibly shift the centre of gravity further from the focuser than the dslr - could be a factor and I may need to therefore do further focuser strengthening).

i'll aim to correct, tilt and coma corrector distancing first as I am fairly confident most other things shouldn't have changed from my setting up procedure, I would get pretty good stars most of the time.

I've ordered a 15mm and a 20mm spacer from TS. in conjunction with my 17-23mm variable spacer, tsoag9, filter draw - i'll be able to get the RCC1 up and running again and avoid that terrible extension tube I had to use.

thanks for the comments i'm hoping the spacers and RCC1 (and better PA) will do the trick. Just a question on collimating through a CC? The MPCC has connectors to use visual, I don't think the RCC1 does, how do you do it for yours? I assume there is a 1.25" eyepiece adaptor available?

[Shiraz (Ray)]

Originally Posted by rustigsmed

Just a question on collimating through a CC? The MPCC has connectors to use visual, I don't think the RCC1 does, how do you do it for yours? I assume there is a 1.25" eyepiece adaptor available?

Unscrew the camera and screw on a 2" to 1.25" adapter that is fitted with a Baader M48 male to female T adapter.

[rustigsmed (Russell)]

Originally Posted by Shiraz

Unscrew the camera and screw on a 2" to 1.25" adapter that is fitted with a Baader M48 male to female T adapter.

too easy thanks Ray - I wasn't thinking it would be that simple I have been concentrating on correct spacing too long!

[rustigsmed (Russell)]

the 2x2 bin i posted with the lines was actually 4x4bin 1min.

here is the 5 min 2x2 bin
https://www.flickr.com/photos/803366...blic/lightbox/

lines are there as well but not as obvious as in 4x4 version.

[Shiraz (Ray)]

just a thought Russell, I recall Alpal reporting horizontal lines on his qhy9 due apparently to the ABG bias setting. If that is in any way related to the lines in your binned images, it may indicate that an internal setting in the camera needs attention. I am sure that Theo will be able to advise.

[rustigsmed (Russell)]

Originally Posted by Shiraz

just a thought Russell, I recall Alpal reporting horizontal lines on his qhy9 due apparently to the ABG bias setting. If that is in any way related to the lines in your binned images, it may indicate that an internal setting in the camera needs attention. I am sure that Theo will be able to advise.

Thanks Ray - I just emailed Theo so hopefully there is a simple software solution - which i'm inclined to think there will be given the clean nature of the 1x1.

I need to work on SGPro file naming conventions - BYEOS had all the details in the file name (iso, time, duration, temp etc) so I didn't have to think about it. Looks like my spacers will arrive by COB Wednesday - 50 euro delivery I don't remember Teleskop Shop being that exy on delivery in the past. itching to get back under the skies.

[gregbradley]

Looking at your images it looks like 2 things. Spacing with your coma corrector is off and this is causing the fat stars in the top left and bottom right corners. Then you have tracking errors causing elongated stars leaning to the left a bit.

I would not touch tilt until those 2 things are nailed down or you will likely make it worse. One thing at a time is best for these sorts of possible multiple issues.

Tilt looks different to that. Its one side fat stars or odd shapes and the other is tight or one corner worse than the others.

Greg.

[rustigsmed (Russell)]

thanks for the comment Greg I think you are right.
I'll await my spacers (35mm) arrival from TS and set that up. I had the RCC1 working well with my dslr setup - moving from the DSLR to the qhy22 the sensor to camera difference is 44mm vs 7.5mm (so 36.5mm extra) I have a different nose piece Dslr was a 0mm M48 bayonet on the qhy22 I have used this http://www.bintel.com.au/Astrophotog...oductview.aspx unfortunately it doesn't say exactly the added distance. perhaps 2mm or 2.5mm so the extra 35mm should nearly be exactly what I need to perhaps plus 0.5mm or 1mm. I do have a variable distance spacer in my imaging train that can be adjusted.

Theo isn't sure Ray, suggested it may be the pixel structure on the wafer or maybe the USB download timing for data flow. Hoping to setup Thursday night with the RCC1 and PA etc in less of a rush.
But in my capture sequence (in SGPro) I did go 4x4, then 2x2 and finally 1x1 without pausing between so the data download from usb could well be the issue it could explain why 1x1 is clean. Perhaps I need to use a pause function between capture to let my ancient laptop cope with doing two things at once? i'm sure there is a way in SGPro. I'll try that first.

[rustigsmed (Russell)]

ok,

so ordered some spacers to couple the RCC1 with the qhy22. they didn't work out too well the distance was right but the threads created additional space for whatever reason. going through about a few hundred combinations i managed to pretty much get spot on the 91.5mm required.

clear night forecast last night so try it all out. again like the other day, problems polar aligning again. it was driving me crazy, the sky was filled with stars and it was taking too long. my routine never zerod in and got worse and worse.
i started to do a more involving troubleshoot and found that those stupid EQ8 clutch levers arent clutching like they have in the past. to fix it you need to use a miniture allen key/hex thing to re-apply the lever at a different angle (all in a small window as to miss the encoders ... anyway i turn the house upside down and couldnt find it. anyway tried a rough quick align, and attempted a few targets. dimmer options were no good drifting all the way, so i decided to do a quick and dirty full NB M42 which turned out ok. it appears that the RCC1 is about right.

Here are some pics

Thors helmet bin 2x2 - stars look a lot better than before
https://www.flickr.com/photos/803366...blic/lightbox/

Horsehead 15mins 1x1 Ha - definitely shows the potential of the setup.
https://www.flickr.com/photos/803366...blic/lightbox/

Moon
https://www.flickr.com/photos/803366...blic/lightbox/

M42
https://www.flickr.com/photos/803366...blic/lightbox/

Russ