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Observing >> Solar Observing and Imaging

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James Cunningham
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Color or B&W new
      #6074516 - 09/11/13 07:38 AM

I am thinking of getting a DMK camera. There are several models on their web page. Which is best for Solar imaging? How about whether I should get the Color model or the B&W model? Thanks.
Jim


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LarryAlvarez
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Re: Color or B&W new [Re: James Cunningham]
      #6074555 - 09/11/13 08:23 AM

If I had to get a new ccd today for the PST I have I think I'd get a "Celestron Skyris 445 CCD Camera - Monochrome". Its inners are from the imaging source and it's USB 3.0. If you already have an older laptop that just has USB 2.0 ports on it then perhaps a USB 2.0 "Imaging Source IS-3MU USB Monochrome CCD". They have one listed on special at OPT. If you really have a deep pocket go for a Point Grey 2.8 or 6 megapixel ccd. I have always preferred CCD's with frame sizes of 1/2 to 2/3 personally. They seam to fit the solar disk size well on my PST or Orion 80ED. Its an expensive purchase to say the least. The one thing you want to make sure of is that you have the laptop to support it and get one that does at least 15 fps or faster. Getting a true monochrome ccd will take your images from the PST from 0 to hero in 60 seconds.

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Old Dinosaur
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Re: Color or B&W new [Re: LarryAlvarez]
      #6074638 - 09/11/13 09:19 AM

The Sun is monochromatic, there's no reason to think about color.
A dedicated monochromatic camera uses all the pixels all the time, therefor always better results.


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brianb11213
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Re: Color or B&W new [Re: Old Dinosaur]
      #6074642 - 09/11/13 09:22 AM

Quote:

The Sun is monochromatic, there's no reason to think about color.
A dedicated monochromatic camera uses all the pixels all the time, therefor always better results.



Agreed, a one-shot colour camera is a serious handicap for solar imaging.


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BYoesle
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Re: Color or B&W new [Re: brianb11213]
      #6074681 - 09/11/13 09:48 AM

Piotr Malinski has a great site which reviews cameras for solar imaging as well as other uses:

http://www.rkblog.rk.edu.pl/

http://www.rkblog.rk.edu.pl/w/p/new-solar-system-imaging-cameras-2013/


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BYoesle
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Re: Color or B&W new [Re: BYoesle]
      #6074689 - 09/11/13 09:50 AM Attachment (7 downloads)

For most narrow-band imaging purposes with solar, the Bayer RGB filter pattern will cut resolution for H alpha in half, and sensitivity by 3/4:

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BYoesle
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Re: Color or B&W new [Re: BYoesle]
      #6074694 - 09/11/13 09:52 AM Attachment (10 downloads)

You can add color (if you want) in post-processing:

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jerwin
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Re: Color or B&W new [Re: BYoesle]
      #6075002 - 09/11/13 12:31 PM

I'm probably wrong, but this is my best understanding of the color vs mono thing. Think of that color chart Bob posted above. When imaging the sun in H-alpha your only getting the red spectrum, so your only really capturing details in the red squares. all those green and blue squares are just kind of wasted. Where a monochrome camera will capture the details in each square. You'll have to make your adjustments later. so at the end of the day on a target like the Sun, your capturing more data in monochrome than color.

Jim


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BYoesle
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Re: Color or B&W [Re: jerwin]
      #6077326 - 09/12/13 03:54 PM Attachment (12 downloads)

You're absolutely right Jim. As you can see in the crop below, for any give square area of significant size, the RGB filter for the Red channel is 1/2 the linear distance horizontally or vertically. So resolution is cut in half. Regarding sensitivity, of the 16 total pixels, only 4 red channels are available; 4/16 = 0.25, so sensitivity is reduced to 25%. Same applies to imaging CaK in the Blue, if the chip is sensitive to this wavelength.

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