Atik Cameras

Author Topic: Horizon monochrome and C-14 Hyperstar  (Read 520 times)

Altouch

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Horizon monochrome and C-14 Hyperstar
« on: October 25, 2021, 02:53:44 am »
I have been playing with a Horizon I monochrome camera on a CGE-1400 Fastar.  Nice f/2 imaging providing 1.5x1 degree field of view. I am using Atik Infinity to capture images. I have had it about a month and getting nice images. Anyone else doing this?  Any experiences learned that should be shared?  One question/observation I have is regarding a fairly smooth gradient in the flat field from top to bottom. The top is darker than the bottom (accentuated by the automatic stretch applied). Is this unusual?

Crooro

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #1 on: October 25, 2021, 02:15:49 pm »
Can you post a photo to see !?

Surely in the recovery phase it is necessary to avoid
to shoot too low on the horizon, close to the Moon and in general from observation sites with
high light pollution. Alternatively, the use of narrow band filters (for example H-alpha)
it can help a lot. If the footage is not for scientific purposes and only after correcting
vignetting and electronic noise respectively with flat field and dark frame, you can use the
"remove gradient" function present in all image processing software. If the
nature is electronic, attention must be paid to calibration images, especially darks
frames that must be taken at the same temperature and with the same duration as the light image.
There are two ways to solve the problem: the first and best way is to shoot dark frames
correct, while the second is to remedy it by applying a bias frame (not necessary
when subtracting correct dark frames).
https://www.flickr.com/photos/126536798@N07/
Mount: Gemini G53F
Optics: Newton Truss 254mm F/3.8
Tecnosky Apo 152/1216
Tecnosky EDT-80/480
Guide: Lodestar
Imaging: G2-4000 Moravian, Atik 414EX

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #2 on: October 29, 2021, 05:29:50 am »
The attached picture is NGC281.  This was done with LRGB and dark frames. I did not shoot flats or bias frames. I stacked the images for each individual color in Affinity Photo, and then combined them with appropriate colors also in Affinity Photo.  There is no gradient top to bottom.  However when I shoot flat fields at 0.001 second (my flat light panel is too bright to shoot slower until I design some neutral density filters for a 355mm aperture) I get a strong top to bottom gradient which is not present in the astrophoto. I am thinking it is a function of shooting flats at such a rapid exposure time - but will do trials this weekend. A sample flat field is attached in the next message. The flat does not match the vignetting I see in other images.  Processing with this flat does not produce a useful image. 

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #3 on: October 29, 2021, 05:31:23 am »
Here is a sample flat mentioned in the previous post.

Crooro

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #4 on: October 29, 2021, 09:37:07 am »
The flats are so wrong - exposure of 0.001seconds does nothing. Then you have to see what you use to make the flats, maybe the light is not homogeneous. When I flat with various filters I use homogeneous plexi to put the light in front to decrease intensity or I move the panel farther away from the optical tube .
https://www.flickr.com/photos/126536798@N07/
Mount: Gemini G53F
Optics: Newton Truss 254mm F/3.8
Tecnosky Apo 152/1216
Tecnosky EDT-80/480
Guide: Lodestar
Imaging: G2-4000 Moravian, Atik 414EX

vince

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #5 on: October 29, 2021, 09:49:08 am »
Hello,

The Infinity software is not really designed for taking calibration files. You will need to use something Artemis Capture or Dusk, for very short exposures with the Horizon you will need to have the "even illumination" box ticked or you will see the gradient you are seeing, this is caused by the sensor readout method.

I hope this helps.

Vince

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #6 on: October 29, 2021, 01:44:14 pm »
Excellent!  I will stop using infinity and switch to Dusk or Artemis capture for calibration images (and maybe play with lights as well). Great news. I had though about readout method but was thinking it was associated with he exposure being so short. Change software and check the correct box.  Flats tonight!  Thank you.

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #7 on: October 31, 2021, 10:33:48 pm »
I was able to take flats that look about right. I have attached one. Dusk worked well.  If I run too long an exposure the top end saturates - but well before 65535. It had a limit at about 4095. This makes sense if the Horizon digitization is 12 bit and not scaled up to 65535. 

Thanks for the advice to use Dusk and not use Infinity for calibration frames.

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #8 on: October 31, 2021, 10:53:44 pm »
Image didn’t appear to make it. Did find the fix for saturation at 4095. Apparently for the Horizon one must check the pad box to pad it out to 16 bit.

Altouch

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Re: Horizon monochrome and C-14 Hyperstar
« Reply #9 on: November 04, 2021, 07:52:50 pm »
Can I make the flat frame actually show up in the forum?  Let’s try one more time.