Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_inspirational_skies.thumb.jpg.a20cdbfeadc049807f6d78e6c00ee900.jpg

Andymod

Please help with QHY8L

Recommended Posts

1 hour ago, LightBucket said:

well not that good, as loads of noise, is the camera being cooled as looks more like a DSLR image with no darks ?

if I bring the curves up a bit and make the background more natural looking, the noise is much worse, hence the black background... :) 

 

Well, the qhy8l, I guess, as that's the thread topic. However, the OP didn't say whether the cooling was on or what it was set to, or how many subs and length of them.

Louise

Share this post


Link to post
Share on other sites
4 minutes ago, Thalestris24 said:

Well, the qhy8l, I guess, as that's the thread topic. However, the OP didn't say whether the cooling was on or what it was set to, or how many subs and length of them.

Louise

Yes realise it’s the QHY8L,was just saying it looked like a DSLR image because of the noise.. :)

  • Like 2

Share this post


Link to post
Share on other sites
6 hours ago, LightBucket said:

well not that good, as loads of noise, is the camera being cooled as looks more like a DSLR image with no darks ?

if I bring the curves up a bit and make the background more natural looking, the noise is much worse, hence the black background... :) 

 

myattempt.jpg

 

5 hours ago, Thalestris24 said:

Well, the qhy8l, I guess, as that's the thread topic. However, the OP didn't say whether the cooling was on or what it was set to, or how many subs and length of them.

Louise

 

5 hours ago, LightBucket said:

Yes realise it’s the QHY8L,was just saying it looked like a DSLR image because of the noise.. :)

Hi Thankyou for all your help, I set the cooling at -20C. The fact that you managed to get anything is a great help. I can try and achieve an image knowing there is data there. Should I be worried about the level of noise?.

Share this post


Link to post
Share on other sites
11 minutes ago, Andymod said:

 

 

Hi Thankyou for all your help, I set the cooling at -20C. The fact that you managed to get anything is a great help. I can try and achieve an image knowing there is data there. Should I be worried about the level of noise?.

Hi

What was your sub length and how many did you stack?

Share this post


Link to post
Share on other sites
2 hours ago, Thalestris24 said:

Hi

What was your sub length and how many did you stack?

300 secs and only 4 in stack. As soon as I can I am going to setup my camera gain etc again and capture a decent amount of subs and a full suite of calibration frames. My interest in the QHY8L has been resurrected. A Massive thanks for everyones input.

  • Like 1

Share this post


Link to post
Share on other sites

I presume you are guiding,  IF so, with a cooled CCD camera, you probably should do 600sec exposures, you'll get better data that way.

Carole 

  • Like 1

Share this post


Link to post
Share on other sites
On 8 January 2018 at 21:14, carastro said:

I presume you are guiding,  IF so, with a cooled CCD camera, you probably should do 600sec exposures, you'll get better data that way.

Carole 

I will go 600 secs next time out and get a full suite of calibration frames, although now my laptop charger has decided to give up charging, it will have to wait until I get another charger. Just my luck at the moment.

Share this post


Link to post
Share on other sites
On ‎10‎/‎01‎/‎2018 at 21:37, sloz1664 said:

High Andy

Have a read of the attached gain & offset procedures for your type of CCD camera

Steve

Gain & Offset.pdf

gain and offset.pdf

Thanks Steve I will have a read now I have a working laptop charger

Share this post


Link to post
Share on other sites
On ‎10‎/‎01‎/‎2018 at 21:37, sloz1664 said:

High Andy

Have a read of the attached gain & offset procedures for your type of CCD camera

Steve

Gain & Offset.pdf

gain and offset.pdf

So I finally found some spare time to have a go at setting up the gain and offset of my QHY8L following the guide above. Everything appeared to be going well until the final step "Complete a photon response plot of CCD". With the camera capped and an exposure of 0.001secs my mean pixel value is 637 which is above 400 so uncapped the camera and began exposures with 0.025secs, my mean pixel value was 64996. increasing exposure to 0.050 secs and the mean value hits max 65535. I calculated my gain to be 11 and offset 108. The guide suggests the mean pixel value should gradually rise?. Whats going on?.

Share this post


Link to post
Share on other sites

Those seem like reasonable numbers?  I use a gain of 14 and offset of 113, so not much different.

  • Like 1

Share this post


Link to post
Share on other sites

Agree with AKB those figures look fine. My gain is 10 & offset of 121.

Steve

  • Like 1

Share this post


Link to post
Share on other sites
Posted (edited)

I think I am finally making small amounts of progress with the QHY8L. 

This image is 7x600s stacked. I used darks, flats and bias. Still trying to get to grips with processing but finally seem to be making progress. 

North American Nebula from a light polluted Sheffield.

 

image.jpeg

Edited by Andymod
  • Like 3

Share this post


Link to post
Share on other sites

Much better Andy, and pretty good from Sheffield.  Onwards and upwards. 

I did have to put my sun glasses on though because of the very bright red ha ha.  

Carole 

Share this post


Link to post
Share on other sites

Hi, keep at it my friend, I have a QHY10 and were having issues about sensitivity amp on amp off etc, and I would be happy if I got something like your North American neb, I learn't that you can take too many darks and bias and not concentrate on the light, luminance and imaging data exp, especially when I was using an 80mm edt as an imager, now have an astrograph and much better  results for me  I found it more important to get a good flat frame library for that scope setup, Tony.

Share this post


Link to post
Share on other sites

The qhy8l is certainly well sensitive in the red part of the spectrum :) The nights are gradually getting longer here! I might be able to do some imaging again in about a month or so....

Louise

Share this post


Link to post
Share on other sites

Thanks to everybody who commented, I had more or less given up with the QHY8L. I spent so many of my limited imaging nights getting no images it destroyed my confidence and almost made me give up altogether. I defaulted to using 600D to rebuild confidence. After everyone's help and calculating the gain and offset for the camera, I just needed a night to grab some data. I hope to practice more at processing and maybe tone down the Ha a bit. My excitement at finally grabbing an image may be the reason the Ha was extreme. Thanks everyone.

Share this post


Link to post
Share on other sites

Andy, did you ever solve your original issue of "rings of varying brightness". I only ask because I have seen something like this my self and it seemed to be a quirk of Photoshop. If I recall, it happened at different zoom levels. I think I was able to get rid of it by zooming to 100% but then the image didn't fit on the screen.

Share this post


Link to post
Share on other sites
19 hours ago, russellhq said:

Andy, did you ever solve your original issue of "rings of varying brightness". I only ask because I have seen something like this my self and it seemed to be a quirk of Photoshop. If I recall, it happened at different zoom levels. I think I was able to get rid of it by zooming to 100% but then the image didn't fit on the screen.

Hi Russell, I didn’t get to the bottom of the rings to be honest, I did wonder if it was condensation on the glass in front of the sensor. When there’s a heavy dew I wrap a small heater band around the spacers between the camera and Flattener.

Share this post


Link to post
Share on other sites

A good friend at Sheffield Astronomical Society, took my stack that I used above and processed it in  Pixinsight. Wow what a difference. I have a lot to learn. 

9B8BE639-35EF-41A4-98A1-AE642B6B8134.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By AKB
      Taken on 15-Dec-2017 (no moon)
      Hyperstar 9.25" with Baader UFC and IDAS P2 filter Avalon M-Uno guided and dithered with Nebulosity and PHD2 20 x 60 seconds Processed in PI  
    • By AKB
      Taken on 15-Dec-2017 (no moon)
      Hyperstar 9.25" with Baader UFC and IDAS P2 filter Avalon M-Uno guided and dithered with Nebulosity 10 x 120 seconds (for a total of 20 minutes) Lightly processed in PI  
    • By AKB
      Another quick snap from last night (15-Dec-2017), and the first time I've imaged the Christmas Tree cluster / Cone nebula.
      Hyperstar 9.25" with Baader UFC and IDAS P2 filter Avalon M-Uno guided and dithered with Nebulosity 15 x 120 seconds (30 minutes total) Lightly (and, no doubt, incorrectly, processed in PI) Help for improvement much needed.
       

       
    • By AKB
      Cracking night, last night (15-Dec-2017) although with temperatures a bit below freezing and gusty winds.  Having discovered that the spacing for my QHY8L on the Hyperstar was incorrect by 3mm despite using the Starizona-supplied spacer, I'm now using the excellent Baader Universal Filter Cell to give me nearer to the correct spacing.  Still not quite there yet, though.
      To check it all out I went for a number of targets for a relatively short time.  Here's my go at the Horsehead.
      Hyperstar 9.25" with Baader UFC and IDAS P2 filter Avalon M-Uno guided and dithered with Nebulosity 20 x 60 seconds Processed in PI  (shhh... I'm still learning) Haven't really got the hang of noise reduction, (and seems my bias or darks aren't handling a bad column) but really the answer is more data, and I suppose this isn't too bad for  just 20 minutes...
      Advice more than welcome.
       

       
    • By AKB
      2017-Oct-12  Eastern Veil
      Hyperstar, QHY8L, 9x5m
      Processed with APP, Nebulosity, and MATLAB.
×

Important Information

By using this site, you agree to our Terms of Use.