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Andymod

Please help with QHY8L

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Hello, I have not posted very often but visit the site a lot. I have owned a QHY8L CCD for just over a year and used it very rarely. After initially using it and completely failing to produce any images, I gave up and returned to my modified Eos 600D. Over Christmas I have began reading 2 books by Steve Richards, "Making every Photon Count" and "Dark Art or Magic Bullet". Revisiting some of my Eos data I am making a small amount of progress improving the processing.

I really want to master using the QHY8L and have looked at some of the previous data I have gathered. Previously I had no discernible image and now the image I have is awful but there is something there which is a step forward for me. The main thing I have noticed is the "Rings" of varying brightness. My question is could this be caused by the spacing of my QHY8L to my Reducer/Flattener. All feedback is genuinely appreciated I would love to produce an image from my QHY8L this year.

Thanks Andy

 

m451217.jpg

rosette qhy.jpg

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I have just noticed when uploading the images that the Varying brightness is not as obvious now?.

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There is definitely some good data there in the second image, just need bringing out.. :)

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The images posted are Jpeg saved from Photoshop. When I look at the Tiff image I have what I can only describe as circles of varying brightness from the centre of the image working outwards.

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Hi

You probably have a slight spacing issue (elongation in the corners) and maybe focus could be tightened a tad. It can be a bit strange moving to a cooled ccd from a dslr but just takes practice/repetition to get used to it :). Make sure you follow the setup (gain, offset) instructions in the manual (there are several online versions of the manual if you google it). Yep, processing properly is a lot of what makes the difference. Oh, and plenty of data :) 

Louise

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4 minutes ago, LightBucket said:

There is definitely some good data there in the second image, just need bringing out.. :)

Really, that's encouraging. Its difficult for me at the moment because I am not sure if its my limited processing skills or an error with setup/camera operation or both which is letting me down.

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1 minute ago, Andymod said:

The images posted are Jpeg saved from Photoshop. When I look at the Tiff image I have what I can only describe as circles of varying brightness from the centre of the image working outwards.

Hi can you do a screen grab? I take it you are calibrating with flats and bias frames, at least?

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1 minute ago, LightBucket said:

No rings on my screen from that tif file, just very green...

Really, That's interesting on my laptop I see a very green image with rings of varying brightness. I have learnt more in this post than I have in the last year. I have a friend at my local astro society who tried to process the last light frames of M45 I took with the QHY8L. He failed to produce anything and suggested my camera may be faulty.

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Can you post a link to the origional autosave file from DSS (assuming you used DSS for stacking) of the rosette...and I will have a go tomorrow and see what I can produce from it..

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Posted (edited)

Hi

It might depend on the software/app that you've used to view the tiff file. Use a proper 16 or 32 bit graphics package or DeepSkyStacker

Louise

ps the autosave tiff file that DSS creates is 32-bit tiff by default, I think

Edited by Thalestris24
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6 minutes ago, LightBucket said:

Can you post a link to the origional autosave file from DSS (assuming you used DSS for stacking) of the rosette...and I will have a go tomorrow and see what I can produce from it..

Link for autosave file from DSS. No calibration frames were used unfortunately, But to be honest any image would be a huge leap forward for me. Thankyou for your help.

Autosave.tif

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3 minutes ago, Andymod said:

Link for autosave file from DSS. No calibration frames were used unfortunately, But to be honest any image would be a huge leap forward for me. Thankyou for your help.

Autosave.tif

See what I can get and let you know tomorrow, as am on iPad at the moment... :)

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I found your image extremely difficult to process because it had bad vignetting and I am certain no flats were taken.  This is probably the cause of your problem, I find images without flats pretty impossible to process.

Here it is attached.  

Andymod SGL rosette.png

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Carole, have you got gradient exterminator as that should sort it, or astroflat Pro....

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Posted (edited)

Hi Andy

I loaded your tif into dss and did a quick histogram align and stretch then saved it to 16-bit tiff and resized it (for convenience) in Paint.net. Actually, Gimp 2.9.8 is a good free package that lets you do levels and curves in 16 (or 32?) bit.

Anyway - you definitely have data!

qhy8l-Rosette.thumb.png.9fc44be08c47d5f66e2d0c30a31b9455.png

 

You probably need more, and possibly longer, subs. It does look like you have a gradient - probably LP?

Louise

ps snap Carole! :)

 

Edited by Thalestris24
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Posted (edited)

You beat me to it lightbucket, I was just doing that when you posted. 

So I have just applied gradient exterminator to it and produced a much better image, but I firstly wanted to show the original poster what the problem was. 

So this one is with GE applied, but it should not be used to compensate for flats.

In conclusion, the data is not bad at all, but needs flats applying. 

Carole 

Andymod SGL rosette2.png

Edited by carastro
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21 minutes ago, carastro said:

I found your image extremely difficult to process because it had bad vignetting and I am certain no flats were taken.  This is probably the cause of your problem, I find images without flats pretty impossible to process.

Here it is attached.  

Andymod SGL rosette.png

 

18 minutes ago, Thalestris24 said:

Hi Andy

I loaded your tif into dss and did a quick histogram align and stretch then saved it to 16-bit tiff and resized it (for convenience) in Paint.net. Actually, Gimp 2.9.8 is a good free package that lets you do levels and curves in 16 (or 32?) bit.

Anyway - you definitely have data!

qhy8l-Rosette.thumb.png.9fc44be08c47d5f66e2d0c30a31b9455.png

 

You probably need more, and possibly longer, subs. It does look like you have a gradient - probably LP?

Louise

ps snap Carole! :)

 

OH MY GOD!!!! Thankyou for your help, I cannot believe that is my data. Correct me if I am wrong, my spacing is reasonable? and if I take Darks and Flats I should see a marked improvement?.

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Spacing doesn't look too bad at all.  

Quote

 if I take Darks and Flats I should see a marked improvement?.

Yup

Carole 

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Posted (edited)

Hi Andy

I think your spacing needs a little tweak but it's only the corners that are affected. Other than that - more data, flats and bias frames (~30 of each) and when you're ready for it, dithering is very helpful :) 

ps darks - maybe. But you might not need them though you can create a darks library, if you like. 

Edited by Thalestris24

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 any reason why when I load the autosave.tif into PS it wont let me apply curves, only if I change to 16bit mode....strange..

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Posted (edited)

Because the autosave saves in 32 bit.  Go into Image/Mode and change it to 16bit.  It will work OK then.

Carole 

Sorry, I see you have already sussed that out.  No idea why it saves in 32bit, I normally used to save the image in DSS giving it my own name and that saves in 16bit, no idea why is should be 32bit in the autosave.

Carole 

 

 

Edited by carastro

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Posted (edited)

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

Edited by LightBucket
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Posted (edited)

 quick run with the Astroflat pro plugin for PS works well with gradient and vignetting..

Edited by LightBucket

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