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QHY600 - Yet another thread!

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#126 anismo

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Posted 19 September 2020 - 07:35 PM

yes, Indeed. 10$ seems like a great investment given the amount of money sunk into so many of these adapters :)  I just hate having to open the filterwheel and fiddle with those tiny screws.. Always worried about scratching the filters


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#127 dghent

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Posted 21 September 2020 - 04:31 PM

I finally got all my adapters in, a GN CTU in, got it put together and a clear and smoke-free night that I could use to seriously first-light it and start working out tilt and spacing. Whew. It only took a few months. This camera has turned out to be quite the journey. I'm running it on an Astro-Physics 130GTX with a Quad-TCC (0.72x reducer), so the optics work out to be 589mm @ f/4.5.

 

Tilt. It's pervasive. I did a quick test run back in July with rough spacing and no tilt correction and the resulting image might have well been hand-painted by Van Gough himself, right after an absinthe bender. I think the center 1/3 was in focus, but it got pretty bad quickly toward the edges.

 

The GN CTU was procured ($100 direct with a custom M68/M54 adapter, such a great deal) and I got a new spacer from Precise Parts. Putting it all together, I had to throw in another 2mm of spacing and am now working out the tilt. The GN CTU will adjust the tilt at 3 points. A full turn of any of the 3 collimation screws will move that part of the CTU 0.2mm, so very fine control can be exerted over the tilt. It's a lot of adjust-expose-inspect-adjust cycles. I'm using CCDInspector which is a fantastic tool for this but it's showing its age with the 120MB FITS files and it'll crash if I accidentally open too many (the magic number seems to be 8. Any more than that and it'll abruptly check out on you.)

 

bMZq7q9.jpg?2

 

I'm going to continue working on the tilt and making sure that it maintains itself between storing the telescope and using it. I think in general I should make sure to keep a hex key at the ready to do any minor adjustments as needed.

 

After all night working on this last night, I did a 20 minute exposure just for grins. mode=0, gain=26, offset=50. Just a screenshot of the raw sub; no calibration:

 

X8yQLIe.png


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#128 anismo

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Posted 21 September 2020 - 05:52 PM

That looks great ! I hear you about the months of journey.. Same here and now the weather has turned . I hope to do final adjustment this week. I hope CTU adjustment will need to be minimal .

 

Here is my train (ignore the cable as I had to swap it a few times). 

 

IMG_8968.jpg


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#129 dghent

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Posted 21 September 2020 - 06:54 PM

Excellent... I meant to ask earlier in the thread; which reducer are you using on the 106? I believe there is quite of a menu of them to choose from.



#130 anismo

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Posted 21 September 2020 - 06:59 PM

Excellent... I meant to ask earlier in the thread; which reducer are you using on the 106? I believe there is quite of a menu of them to choose from.

 I have the QE reducer.. However, with this train, I need customer adapter to get it in and with the reducer, at F3.5, the tilt control becomes even more harder to manage. My plan is to get this thing up and running without the reducer and then get the adapter and try to work it in.. 


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#131 anismo

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Posted 27 September 2020 - 11:41 PM

First light! Here is a highly resized version for CN. I only could manage 16x10 min/channel. But I decided to process it..

This is with the default mode (10 offset, 26 gain). I think may need to add pedestal.. there are black flecks in the background. I only. used matched dark (10 minute dark at -5C).

But overall, this is very CCD like.. the calibration quality is very good.  

 

Need to adjust the CTU.. (this is with no changes) but the allergies are sky high and I cant seem to spend anytime out without getting a major hit.. so it will have to wait :D

IC1805_SHO_FINAL_CN.jpg

 

Larger at: https://astrob.in/full/ahsimf/0/


Edited by anismo, 27 September 2020 - 11:47 PM.

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#132 Peter in Reno

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Posted 29 September 2020 - 10:30 PM

I think may need to add pedestal.. there are black flecks in the background.

You could use PixInsight Statistics tool to see if the minimum ADU hits zero value of at least one calibrated subs.

 

Awesome image. I still have not imaged with my QHY600M camera due to smokey sky. The smoke was clearing but came back thanks to Napa Valley fire.

 

Peter 


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#133 anismo

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Posted 29 September 2020 - 10:50 PM

Thanks Peter. Yes.  I need to check that value and add it and reprocess,. 

I finally got the CTU adjusted (and I have to thank @ezwheels for the suggestion of the CTU - It makes adjustment so much more easier) and I think I got it real close to very good stars. 

 

I also need to test this with different gains and durations.

 

With 10 minute narrowband, it is pretty good but I want too check its performance at higher gain and see if that helps with very faint targets like the Sh2-240). Overall, the camera is really nice.


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#134 Peter in Reno

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Posted 29 September 2020 - 11:25 PM

Would increasing offset during capture help avoid dealing with pedestal during calibration? 

 

Peter 



#135 rgsalinger

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Posted 29 September 2020 - 11:46 PM

I seem to have the same problem with black flecks in my images. I was thinking of trying to adjust the offset because some of my older ones simple do not have this problem at all. I have matched darks and lights 300 seconds binned 2x2 with the same gain 26 and offset 10. Using statistics in PI my "minimum" value is .04 versus a median of 759. 

 

Here's an example. I've been able to process them out but it's clearly a mistake of some kind on my part in the first place. 

 

black_flecks.JPG

 

Ideas appreciated.

 

Rgrds-Ross



#136 Peter in Reno

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Posted 29 September 2020 - 11:51 PM

I seem to have the same problem with black flecks in my images. I was thinking of trying to adjust the offset because some of my older ones simple do not have this problem at all. I have matched darks and lights 300 seconds binned 2x2 with the same gain 26 and offset 10. Using statistics in PI my "minimum" value is .04 versus a median of 759. 

 

Here's an example. I've been able to process them out but it's clearly a mistake of some kind on my part in the first place. 

 

attachicon.gifblack_flecks.JPG

 

Ideas appreciated.

 

Rgrds-Ross

It's my understanding that if you bin, it affects the offset. I'm not sure whether the offset should be increased for binned 2x2 over 1x1.

 

Peter 



#137 axlns

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Posted 30 September 2020 - 01:44 AM

I ordered QHY600 as my second camera and its on the way to me, and I'm looking for what I need for proper connection to my OTAs'. I'm concerned about tilting and looking for ways to incorporate CTU, but I'm not sure if I have enough backfocus to utilize Neumann CTU, as its minimum optical path is 17.3mm according to spec on the site.

 

I have 2 OTAs:

  1. field flattened APO with 88mm backfocus from M68x1 male thread
  2. Reflector with corrector with 69.5mm backfocus from M68x1 male thread

 

my understanding that QHY600 + QHYCFW-L + QHYOAG-M will have a minimum of 58mm of backfocus from M54 female thread. this is how I got this value

 

  • QHY600M 17.5mm
  • QHY600M adapter 6mm
  • QHYCFWL 21.5mm
  • QHYOAG-M 13mm

do I get it right? also with 3mm thick filters (I ordered Chroma) I probably should use 57mm instead in my calculations?

 

so it seems there is no way for me to use Neumann CTU with reflector (57mm+17.3mm is already over the required 69.5mm and that not considering any M68->M54 adapters) unless I don't use OAG and replace it with guiding scope, that will save me 13mm of backfocus? But maybe I'm missing something?

 

what kind of CTU you guys are using? Neumann XL? what available backfocus you are dealing with? what adapters you are using between your focusers and Neumann XL and between Neumann XL and QHY600?

 

thanks!


Edited by axlns, 30 September 2020 - 01:49 AM.


#138 dghent

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Posted 30 September 2020 - 07:54 AM

55mm backfocus is very limiting. The CTU itself consumes 17 and change mm, depending on how it is adjusted, so even without the OAG you would be beyond the 55m common backfocus distance of most flatteners. There is the short backfocus variant of the QHY600, which has a backfocus of 8mm vs. the standard 17.5, a savings of 9.5mm. The only downside of the SBF version is that it's available only on the -PH version of the camera, not the Lite or Pro, and it may introduce cases where the camera window heater could be overcome easily in heavy dew environments.


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#139 anismo

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Posted 30 September 2020 - 08:24 AM

I ordered QHY600 as my second camera and its on the way to me, and I'm looking for what I need for proper connection to my OTAs'. I'm concerned about tilting and looking for ways to incorporate CTU, but I'm not sure if I have enough backfocus to utilize Neumann CTU, as its minimum optical path is 17.3mm according to spec on the site.

 

I have 2 OTAs:

  1. field flattened APO with 88mm backfocus from M68x1 male thread
  2. Reflector with corrector with 69.5mm backfocus from M68x1 male thread

 

my understanding that QHY600 + QHYCFW-L + QHYOAG-M will have a minimum of 58mm of backfocus from M54 female thread. this is how I got this value

 

  • QHY600M 17.5mm
  • QHY600M adapter 6mm
  • QHYCFWL 21.5mm
  • QHYOAG-M 13mm

do I get it right? also with 3mm thick filters (I ordered Chroma) I probably should use 57mm instead in my calculations?

 

so it seems there is no way for me to use Neumann CTU with reflector (57mm+17.3mm is already over the required 69.5mm and that not considering any M68->M54 adapters) unless I don't use OAG and replace it with guiding scope, that will save me 13mm of backfocus? But maybe I'm missing something?

 

what kind of CTU you guys are using? Neumann XL? what available backfocus you are dealing with? what adapters you are using between your focusers and Neumann XL and between Neumann XL and QHY600?

 

thanks!

 

Yes you are right (you will have to account for the filter thickness here as well.. that will consume 1/3 of filter thickness.. so 56mm if using 3mm filters). My Tak E130D newt requires only 55mm backfocus, so I cant even use it with the OAG (CTU is not even an option there).  With my FSQ, there is plenty of space but with its QE reducer, I have too figure ouot custom adapters to use it. 

I am using the M68 version of CTU and it came with one M68 gender changer. I ordered M72->M68 female from Baader and had M68 to M72 made from precise parts so I could just reuse the rest of the adapter with or without the CTU . Apparently gerd neumann can build additional adapters as well (which would have saved me some money if I had known earlier). 


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#140 anismo

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Posted 30 September 2020 - 08:28 AM

I seem to have the same problem with black flecks in my images. I was thinking of trying to adjust the offset because some of my older ones simple do not have this problem at all. I have matched darks and lights 300 seconds binned 2x2 with the same gain 26 and offset 10. Using statistics in PI my "minimum" value is .04 versus a median of 759. 

 

Here's an example. I've been able to process them out but it's clearly a mistake of some kind on my part in the first place. 

 

attachicon.gifblack_flecks.JPG

 

Ideas appreciated.

 

Rgrds-Ross

Yes, Similar issue in mine. Here is 4:1 of calibrated frame (No bias used. Just matched dark  and Flats used in calibration. No dark flats as well)

 

Screen Shot 2020-09-30 at 8.25.51 AM.jpg



#141 lucam

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Posted 30 September 2020 - 08:44 AM

Are the black spots also in the raw lights or only after dark subtraction? If the binning factor and offset of lights and darks is matched, changing offset will not help. An output pedestal will fix the issue. However, with the low noise of this camera it's difficult to understand why a properly prepared master dark should give these black spots. What gain are you using?


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#142 axlns

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Posted 30 September 2020 - 09:03 AM

55mm backfocus is very limiting. The CTU itself consumes 17 and change mm, depending on how it is adjusted, so even without the OAG you would be beyond the 55m common backfocus distance of most flatteners. There is the short backfocus variant of the QHY600, which has a backfocus of 8mm vs. the standard 17.5, a savings of 9.5mm. The only downside of the SBF version is that it's available only on the -PH version of the camera, not the Lite or Pro, and it may introduce cases where the camera window heater could be overcome easily in heavy dew environments.

unfortunately I already ordered standard PH version. also I want to reiterate that I'm dealing with 88mm and 69.5 backfocus requirements with my 2 setups; thats already with flatteners, so not 55mm fortunately.

 

with APO I need to place camera sensor at 88mm from M68x1 male thread I have on my focuser. so for that setup I probably can fit Neumann CTU XL; I only need to figure out what adapters I need. I also need to fit some kind of rotation system.

 

with reflector I need to place camera sensor at 69.5mm from M68x1 male thread, and here I think I will not be able to fit CTU unless I remove OAG;

I have Moonlite 2.5'' focuser on that reflector and it has rotation system builtin, so thats part solved.

so I have a dilemma here ; I think OAG gives better guiding, and that is more important for larger FL of reflector; I'm not sure if guiding through guiding scope will give me as good results. on the other side I think CTU will be probably even more important with reflector than APO.

 

Yes you are right (you will have to account for the filter thickness here as well.. that will consume 1/3 of filter thickness.. so 56mm if using 3mm filters). My Tak E130D newt requires only 55mm backfocus, so I cant even use it with the OAG (CTU is not even an option there).  With my FSQ, there is plenty of space but with its QE reducer, I have too figure ouot custom adapters to use it. 

I am using the M68 version of CTU and it came with one M68 gender changer. I ordered M72->M68 female from Baader and had M68 to M72 made from precise parts so I could just reuse the rest of the adapter with or without the CTU . Apparently gerd neumann can build additional adapters as well (which would have saved me some money if I had known earlier). 

thats interesting info that gerd neumann can build additional adapters, I will probably contact them and ask for their input.

 

btw, do you think this CTU is any good - https://www.teleskop...l-Adapters.html

it has shorter optical path (9 to 12mm)



#143 anismo

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Posted 30 September 2020 - 09:06 AM

Yes. I am planning to reprocess with an output pedestal. This is with the default mode (Mode 0? - 10 offset and 26 gain) . The uncalibrated sub's min pixel value is 85 ADU and after calibration it is closer to 0

 

Screen Shot 2020-09-30 at 9.03.06 AM.png



#144 anismo

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Posted 30 September 2020 - 09:07 AM

Here is the same frame calibrated.

 

Screen Shot 2020-09-30 at 9.03.25 AM.png



#145 rgsalinger

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Posted 30 September 2020 - 09:08 AM

Gain is 26 and offset is 10 all images are binned 2x2. I checked one of the dark spots and it corresponds to a hot pixel in the uncalibrated frame. The dark spots are "0" there around .03 but once stretched they become more obvious. This seems to have started when I changed over from -10 to 0. So, I took a fresh set of darks/bias/flats last night and will redo everything this morning. 

 

Here's an earlier calibrated sub I took back in May that doesn't have them. 

 

no_black_flecks.JPG

 

 

Rgrds-Ross



#146 axlns

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Posted 30 September 2020 - 09:12 AM

... The GN CTU was procured ($100 direct with a custom M68/M54 adapter, such a great deal) ...

where you got that deal? M68 GN CTU on their site has price of ~270 EUR...



#147 jdupton

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Posted 30 September 2020 - 09:16 AM

Anis,

 

Yes. I am planning to reprocess with an output pedestal. This is with the default mode (Mode 0? - 10 offset and 26 gain) . The uncalibrated sub's min pixel value is 85 ADU and after calibration it is closer to 0

 

   Note that to get a better picture of the clipping, you have to uncheck the Statistics Process option for "Unclipped". Otherwise, PI ignores all clipped pixels (both 0's and 1's) for generating the statistics. For the calibrated screen shot, the mean is very low but also shows that there was considerable clipping happening. (I calculate that there were 116,661 clipped pixels in the calibrated image.)

 

 

John


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#148 rgsalinger

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Posted 30 September 2020 - 09:39 AM

Well, once I checked the unclipped box, I got a bunch of 0 pixels. I can see how to add a pedestal if I calibrate using the Calibration Process but there doesn't appear to be an option to add a pedestal using WBPP. Is that correct? 



#149 Peter in Reno

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Posted 30 September 2020 - 09:50 AM

I always use manual calibration using Image Calibration instead of BPP or WBPP because I have better control. It doesn't take much longer to operate PI's IC.

 

Peter 



#150 anismo

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Posted 30 September 2020 - 10:07 AM

Anis,

 

 

   Note that to get a better picture of the clipping, you have to uncheck the Statistics Process option for "Unclipped". Otherwise, PI ignores all clipped pixels (both 0's and 1's) for generating the statistics. For the calibrated screen shot, the mean is very low but also shows that there was considerable clipping happening. (I calculate that there were 116,661 clipped pixels in the calibrated image.)

 

 

John

Thanks John. Here they are . Seems like definite clipping going on. Would the increased mean in uncalibrated due to the hot pixels?  

 

Screen Shot 2020-09-30 at 10.04.02 AM.jpg Screen Shot 2020-09-30 at 10.03.56 AM.jpg




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