Author Topic: New QHY8  (Read 4113 times)

moebius9

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New QHY8
« on: October 27, 2009, 11:20:20 AM »
Hello,

This is my first message and I am sorry for my poor english. I live in France and english is not my mother language.

I bought a QHY8 a few days ago; I dont want to make nice pictures but only to display in one shot a dim objet of the sky on my PC monitor.
For the moment, I use a Meade DSI III monochrome and it works very well.
After two nights of trying that QHY8, I was very disapointed: quite nothing on my monitor after 15 minutes exposure on M27, even in binning 2x2.

I send back that camera to the shop.

May be there is something wrong in my way of using that camera.
Help please !

My setup:
- Intes M703 180/1800 + 0.63
- soft given by the shop (M42 Optic)

Michel




QiuHY

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Re: New QHY8
« Reply #1 on: October 27, 2009, 07:53:28 PM »
Hello,

      Sorry to hear this. You should test the camera when received it before capture the DSO .Has camera response to the light or not?  Or you have not strech the image?
First should check if the hardware is correct.

Best regards,
T

moebius9

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Re: New QHY8
« Reply #2 on: October 28, 2009, 12:57:20 AM »
Hello,

      Sorry to hear this. You should test the camera when received it before capture the DSO .Has camera response to the light or not?  Or you have not strech the image?
First should check if the hardware is correct.

Best regards,
T

Thank you for your answer.
As I said I sent back that camera to the shop, M42 Optic, happy that they accept to cancel my order . I think that they will test it in a few days.
I tested it during the day and yes it works.
During my night tests, the gain was 60%, the offset 110% as advised; even if I can use english, the soft was in french language and I read it many times.
I write here, hopping that there is a solution to my problem, that I did not understand something important. I should be very pleased to get that CCD again if I was sure to succeed in making color live one shot with it.

Michel


Gama

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Re: New QHY8
« Reply #3 on: October 28, 2009, 01:26:58 AM »
The problem is that it is NOT a web cam. So simple pictures are NOT possible.
You need to get image, convert to color, stretch, and process.

If the camera works during day, then a setting, either gain, offset, etc needs to be set correctly. This needs to be done manually, and so once obtained, it is then easier next time.

Theo.

moebius9

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Re: New QHY8
« Reply #4 on: October 28, 2009, 03:38:26 AM »
The problem is that it is NOT a web cam. So simple pictures are NOT possible.
You need to get image, convert to color, stretch, and process.

If the camera works during day, then a setting, either gain, offset, etc needs to be set correctly. This needs to be done manually, and so once obtained, it is then easier next time.

Theo.


OK, but the DSI III is not a web cam I suppose.

Well, the fact is that the shop knew very well what I wanted to do and that they sold me that cam for that purpose.
I am sure that the QHY8 is a very good cam but not for me  :(.

I own a Canon 350D and will use it for my color live one shot; it seems much more comfortable.

Michel


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Re: New QHY8
« Reply #5 on: October 28, 2009, 05:37:11 AM »


      To use the CCD camera, there is some basic conception of CCD should be learn. Such as the 16bit imaging, stretch etc. Otherwise you will still stay in the DSLR time.
There is a lot difference that process the CCD image and the DLSR image.



moebius9

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Re: New QHY8
« Reply #6 on: November 01, 2009, 08:18:58 AM »


      To use the CCD camera, there is some basic conception of CCD should be learn. Such as the 16bit imaging, stretch etc. Otherwise you will still stay in the DSLR time.
There is a lot difference that process the CCD image and the DLSR image.




I think that you are right.
The camera is back to the shop where they will test it.
I have been said on the "astro-quebec" group that may be I had not checked the "auto stretch" parameter. Of course I had not, for I did not know what it means.
If it is the only true reason, I will be glad to learn the spécific CCD semantic in order to be able to use that QHY8  :-\.

Michel

Gama

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Re: New QHY8
« Reply #7 on: November 01, 2009, 08:49:20 PM »
Yes, if you have not stretched it, it will be very dark, with no nebulosity showing.
I have also made that mistake many times.. Sometimes i still forget to do it  :D .

Theo

moebius9

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Re: New QHY8
« Reply #8 on: February 07, 2011, 08:02:07 AM »
Yes, if you have not stretched it, it will be very dark, with no nebulosity showing.
I have also made that mistake many times.. Sometimes i still forget to do it  :D .

Theo

Hello,

I did learn to stretch my pictures using Nebulosity, Photoshop, PaintShop Pro and PixInsight, I changed my mak F10 for a newton F5, but that CCD seems always very few sensitive.
From my garden, I stopped trying to shoot too dim nebulae; 15 minutes exposure on NGC 2244 gives me a too poor signal to obtain a good result, when other people have it with a 350D !
I am very disappointed: maybe my bad sky not so far from town, maybe something else. Modifying the gain and the offset had no efficiency...

What else ? (as says George Clooney)  ;D.

Michel

Gama

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Re: New QHY8
« Reply #9 on: February 07, 2011, 08:48:39 PM »
A single 15 minute image is not going to get you a faint galaxy.
Regardless of which camera, 15 minutes isnt enough time to bring up detail.
Why not post the histogram of your image (Raw)  and after a stretch, and we can see if you have the ofsett and gain correct.
We cant help unless we see what you are doing.

Theo.

moebius9

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Re: New QHY8
« Reply #10 on: February 08, 2011, 02:19:03 AM »
A single 15 minute image is not going to get you a faint galaxy.
Regardless of which camera, 15 minutes isnt enough time to bring up detail.
Why not post the histogram of your image (Raw)  and after a stretch, and we can see if you have the ofsett and gain correct.
We cant help unless we see what you are doing.

Theo.


You give me some hope.
Here are the two histograms, raw an stretched.
I used the gain and offset as set on my version of Nebulosity2 (1% and 110%).





I did not succeed to keep off the blue color downside the stretched picture.

Michel

Gama

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Re: New QHY8
« Reply #11 on: February 08, 2011, 03:50:15 AM »
If thats a single frame, i really cant see what your complaining about. :o

But you need to add gain, so i recommend you read how its done.


This is from the QHY-10/12 manual..


Setting the GAIN and OFFSET
 
Usual Calibration Method:
1. Set the Gain=0
2. Set the exposure time to 0 and cover the lens-this
is a BIAS frame .
3. Watch  the  local average of  the  captured  images
(can use the Noise Analyze  function of  EZCAP)
4. The ideal average value is around 500 to 1000.  If
the value is higher, then you should reduce the
OFFSET.  If the value is lower then you should
increase the OFFSET.
5.  Repeat  steps  2- 4  to  obtain  the  ideal  OFFSET

Note A: For some  QHYCCD products when you
use bin modes of  2x2,3x3,4x4, images may
reach 65535 even with gain set to 0. 
6. Open  the  lens cover and  increase  the exposure
time.   Use  a  uniform  light  source,  such  as  light
boxes  or  an  LCD  screen,  and  take  a  saturated
exposure of the image.
7. Watch  the  local  average  value  of  the  captured
images if the value is is less than 60,000, you need
to increase the value of GAIN, if the value is 65535,
then reduce the GAIN .
8.Repeat steps 6-7  to obtain  the appropriate GAIN
value.
9.Under  the  GAIN,  repeat  steps  2- 4,  and  obtain
more accurate OFFSET.

See if this helps you.

Theo

Gama

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Re: New QHY8
« Reply #12 on: February 08, 2011, 04:01:59 AM »
Also, are you saving them as FIT or as TIFF files ?
Because if you save them as TIFF, you HAVE to stretch before saving the file.
So you need to use software that processes FIT files, and stretch it first before saving as TIFF.

Theo.

moebius9

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Re: New QHY8
« Reply #13 on: February 08, 2011, 04:26:55 AM »
Also, are you saving them as FIT or as TIFF files ?
Because if you save them as TIFF, you HAVE to stretch before saving the file.
So you need to use software that processes FIT files, and stretch it first before saving as TIFF.

Theo.


Thanks for your calibration method.
I understand that there is no problem with my QHY8; good news, I only have to make a better stretching I suppose...and accept to make very long exposures. If I cant help it, OK  :)

Nebulosity gives me FIT files. I use DeepSkyStacker to staks these FIT files and save the result as TIFF file without stretching it. I am wrong ?
The reason is that my PhotoShop is old (version 6)  and cannot read Fit files  :'(.

Michel 

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Re: New QHY8
« Reply #14 on: February 08, 2011, 10:35:34 AM »
Saving as TIFF before stretching WILL give you very low level.  I find you need to stretch before saving as TIFF. Maxim is the same. If i save the file as TIFF before i stretch it, i find i lose all my data and, like you, image is really weak, and very dark.

Try and stretch before exporting into a TIFF format.

Regards

Theo