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need help Monochrome OR Color CCD


doseri
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Dear all

after two years issues with unmodified canon 500d and bad Quality images , with high noise Because high chip temperature over+50c ,now the time to go cooled ccd, I did the searches and I read the same post on how to choose ccd , but I Confused between monochrome or color ,with  consideration all the following points:

  1. high light pollution on site
  2. very hot and bad weather most of the time
  3. I do not have long time in the session 4 -5 hours
  4. Sony chip or Kodak ccd noies
  5.  Quality  and supporter ( sbig ,qhyccd)
  6. need very good cooling, me average temperature 37c  ambient in summer
  7. Beginner in astro imaging

i like from all to give me a Suggestions and feedback from there experiences to help me to get the best Choose in long-tram on points, the Budget not more than 2000$ and my setup is:

  • skywatcher neq6 pro
  • gso 200mm f/5 Newtonian withSkywatcher 0.9x Coma
  •  ShortTube 80st guide scope
  • meade dsi pro guide cam

regards

sam
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You will need to determine which is the worst problem.

As you do not give a location it makes it difficult to guess.

If you go for narrow band then the light pollution problem is removed, or at least significantly reduced.

However you then need to get exposures in R, G, B and it would seem L.

Each of these is as long or longer then the single colour exposure so lets say the total exposure times is 4x.

How many clear nights do you get?

From general information we get about 1 clear night in 6,

So if you went for narrow band and took say one colour a night you are in effect looking at close to 3 weeks to get what you would have otherwise done in 1 night.

Those clear night could well have to fall at a suitable time, if you work then you likely cannot go imaging for 4 hours on a Wednesday if working on a Thiusday.

So yes NB will answer the LP aspect, but it introduces others problems.

In some posts you will realise that some NB imagers collect data over several weeks on one image.

Edited by ronin
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You will need to determine which is the worst problem.

As you do not give a location it makes it difficult to guess.

If you go for narrow band then the light pollution problem is removed, or at least significantly reduced.

However you then need to get exposures in R, G, B and it would seem L.

Each of these is as long or longer then the single colour exposure so lets say the total exposure times is 4x.

How many clear nights do you get?

From general information we get about 1 clear night in 6,

So if you went for narrow band and took say one colour a night you are in effect looking at close to 3 weeks to get what you would have otherwise done in 1 night.

Those clear night could well have to fall at a suitable time, if you work then you likely cannot go imaging for 4 hours on a Wednesday if working on a Thiusday.

So yes NB will answer the LP aspect, but it introduces others problems.

In some posts you will realise that some NB imagers collect data over several weeks on one image.

Could I respectfully disagree.

You don't need to add RGB to narrowband unless you want a small improvement to star colour.

Narrowband aside it is quicker to achieve a finished image with mono-LRGB than OSC.

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You will need to determine which is the worst problem.

As you do not give a location it makes it difficult to guess.

If you go for narrow band then the light pollution problem is removed, or at least significantly reduced.

However you then need to get exposures in R, G, B and it would seem L.

Each of these is as long or longer then the single colour exposure so lets say the total exposure times is 4x.

How many clear nights do you get?

From general information we get about 1 clear night in 6,

So if you went for narrow band and took say one colour a night you are in effect looking at close to 3 weeks to get what you would have otherwise done in 1 night.

Those clear night could well have to fall at a suitable time, if you work then you likely cannot go imaging for 4 hours on a Wednesday if working on a Thiusday.

So yes NB will answer the LP aspect, but it introduces others problems.

In some posts you will realise that some NB imagers collect data over several weeks on one image.

I'm afraid this post is totally incorrect.

Firstly narrowband is not LRGB. LRGB imaging is broadband imaging.

Secondly LRGB imaging is faster  than one shot colour at least in the ratio 6 to 4  and is probably even faster than that. (If I really have to run through this sum again I will but, briefly, L = R+G+B which has to be three times faster than R or G or B, so when shooting L you are working 3x faster than an RGB system can ever work. An OSC system is, obviously, an RGB system. It cannot take luminance.)

LRGB over one shot colour will possibly have a small impact in combating LP but the real secret of monochrome imaging is narrowband, not LRGB.

In narrowband imaging with a mono camera you use very restricted filters (Ha is a thin slice out of red, O111 is a thin slice out of the blue-green borderline, etc etc) and either blend them as if they were genuine broadband colours or add them to a broadband (full colour) image to enhance structural detail.

When will this nonsense about LRGB being slower ever end? The system was invented as a time saver and it works.

Olly

 http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

Edited by ollypenrice
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i thing the new Sbig with the new pixel layout which include L could turn imaging on its head as its a camera which does LRGB at once, if the processing will support it. STF-8050SC

trying to find the article i read.

Sbig seem to have removed the page however i found this

"Instead of an RGGB matrix filter it has a RLGLGLBL TrueSense Sparse Color Filtermatrix"

http://www.cosmotography.com/images/small_ngc6853.html

cant find it there

Ian king has this image on his site

http://www.iankingimaging.com/images/products/originals/stf8050b.jpg

Edited by Earl
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i thing the new Sbig with the new pixel layout which include L could turn imaging on its head as its a camera which does LRGB at once, if the processing will support it. STF-8050SC

trying to find the article i read.

Sbig seem to have removed the page however i found this

"Instead of an RGGB matrix filter it has a RLGLGLBL TrueSense Sparse Color Filtermatrix"

http://www.cosmotography.com/images/small_ngc6853.html

cant find it there

Ian king has this image on his site

http://www.iankingimaging.com/images/products/originals/stf8050b.jpg

Interesting, but even here it is not a luminance camera since all the R,G and B filtered pixels are filtered none the less. This is clearly an attempt to boost sensitivity by learning from the LRGB speed benefit (confirming that this benefit exists!) It might well be a good idea in AP.  What remains questionable in the Bayer Matrix on OSC cameras is the presence of a double dose of green filters. I shoot equal doses of R,G and B and not a double dose of G, so I can't see why, in AP, we should need twice as much green as red or blue. (I stress that I don't see why we would want this. I don't assert that we don't because I don't know the arguments. :grin: ) The term 'sparce colour' is an excellent one and describes exactly what LRGB imaging is all about. It is just that, 'sparse colour.' You work superfast in all colours at once (Luminance) then add sparse colour information because you don't need much colour information to 'colour in' the luminance. And you can bin it 2x2 to save even more time.)

Could I respectfully disagree.

You don't need to add RGB to narrowband unless you want a small improvement to star colour.

Narrowband aside it is quicker to achieve a finished image with mono-LRGB than OSC.

I entirely agree that you don't need to add RGB to NB images but there is every reason to add NB to natural colour images.

Olly

Edited by ollypenrice
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I entirely agree that you don't need to add RGB to NB images but there is every reason to add NB to natural colour images.

Olly

I try to keep to the point but I usually end up being overly brief.

To the OP- For the temperatures you're working with the QSI cameras will provide a much greater level of cooling than the Atiks but there is a cost to be paid (as always).

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When will this nonsense about LRGB being slower ever end? The system was invented as a time saver and it works.

One point about LRGB imaging is that you need *all* the components from all the channels before you can start to compose a colour image out of them.

With a OSC (One Shot Colour) camera, you incrementally add more subs to your running total, so you can stop at any time with a full set of data (albeit noisier with fewer subs).

In this case, Sam says he (she?) has certain limitations:

  • bad weather
  • short sessions
  • beginner (though hopefully that won't last long)

which would increase the productivity from a quick and simple setup. One which would get *something* out of a session that could be cut short by unforeseen circumstances.

My advice would be to start simple with an OSC solution and if circumstances permit, move up to a more complex (and more costly) Mono + filters imaging setup as imaging experience, available "shooting" time and money permit. This doesn't have to be a one-time solution - one that will bought, complete, on day #1 and never changed (as we all know people buy stuff :grin:  as an alternative to using it) but it will be possible to sell the original OSC camera to free-up cash to upgrade with.

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My advice would be to start simple with an OSC solution and if circumstances permit, move up to a more complex (and more costly) Mono + filters imaging setup as imaging experience, available "shooting" time and money permit. This doesn't have to be a one-time solution - one that will bought, complete, on day #1 and never changed (as we all know people buy stuff :grin:  as an alternative to using it) but it will be possible to sell the original OSC camera to free-up cash to upgrade with.

Interesting this one ................... I had a OSC for a short period of time and found the processing very difficult indeed. The mono camera on the other hand I find much easier to process. I think it's much more forgiving all round.

The OP also mentions needing good cooling - Well I can certainly vouch for the QSI giving me excellent cooling in Spain. Also, with a mono camera narrowband will go a long way to negate the light pollution that the OP mentions. 

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Interesting this one ................... I had a OSC for a short period of time and found the processing very difficult indeed. The mono camera on the other hand I find much easier to process. I think it's much more forgiving all round.

Yes, It's a good point.

I'm not an economist but there's a sound principle that one places the highest value on the scarcest resource. It's my understanding that in this case the one that's at a premium is imaging time (and possibly the motivation to get out, set up and DO IT) - hence everything else is secondary to catching the photons. If the weather is bad, then there's more time for processing :grin:. Though maybe the biggest difficulty Sam has is catching the *right* photons, not the thermally induced ones or the LP ones.

To modify the trite and unhelpful adage "the best telescope is the one you use", I'd reckon the "best" solution is whichever ones leads to collecting the greatest number and most usable subimages.

Edited by pete_l
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With an electric filterwheel you can set up a capture sequence which might be L (bin1) R(bin2) G (bin2) B ( bin2) in as many repeats as you like. This goes a very long way to negating the 'one at once' disadvantage but that disadvantage does exist in that getting an incomplete set remains possible. I would still back LRGB to beat OSC convincingly on a short data shoot. (I often extract a synthetic luminance layer from my RGB and add it to my real luminance. Casual theory would suggest that three hours of RGB should be worth about one hour of luminance. In fact it never is. I usually weight it around 22% rather than 33%. That suggests that the speed advantage of LRGB is greater then 6 to 4.)

When I reviewed LRGB versus mono a few years ago I suggested that one nice thing in OSC was needing only one flat. I have since discovered that, with a closed electric wheel, I don't need separate colour flats forLRGB. The luminance flat works fine on all the others.

Like Sara I would advise caution in respect of the perceived simplicity of OSC imaging. It brings its own complications and I, too, found it quite tricky to process on occasion. I think this is mainly because of the relatively poor signal.

OSC, with its reduced sensitivity, works best when you increase exposure lengths over a mono equivalent. This is fine if your guiding is up to it.

Olly

Edited by ollypenrice
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Interesting, but even here it is not a luminance camera since all the R,G and B filtered pixels are filtered none the less. This is clearly an attempt to boost sensitivity by learning from the LRGB speed benefit (confirming that this benefit exists!) It might well be a good idea in AP.  What remains questionable in the Bayer Matrix on OSC cameras is the presence of a double dose of green filters. I shoot equal doses of R,G and B and not a double dose of G, so I can't see why, in AP, we should need twice as much green as red or blue. (I stress that I don't see why we would want this. I don't assert that we don't because I don't know the arguments. :grin: )

Olly

Now I have been pondering is this chip reading red as to red and two luminance or is the luminance seperate, i think its viewing the blocks as 4 LRRL as just the red, so that could be seen as R+L What we really would benefit from its triangular pixels to avoid the repeated G, is that even possible though?

Edited by Earl
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I am a great believer in using OSC CCD cameras and have never understood the argument about the difficulty in processing the data produced as I have always found it intuitive and straightforward. However, there are without doubt advantages in using a mono + filter solution in the form of higher resolution images and greater flexibility which is why I use both types.

For the OP, with the issues that they have to contend with, a mono + filters solution would be the best choice IMHO and the great cooling capabilities of QSI CCD cameras make them a compelling choice. Further, I'd be tempted to suggest using just two filters, Ha and OIII to produce bi-colour images when tackling emission objects as this will combat LP and cut down the narrowband imaging time by at least 33%. Worse case scenario, the OP should end up with a half decent black and white image from their sessions!

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Dear all

after two years issues with unmodified canon 500d and bad Quality images , with high noise Because high chip temperature over+50c ,now the time to go cooled ccd, I did the searches and I read the same post on how to choose ccd , but I Confused between monochrome or color ,with  consideration all the following points:

  1. high light pollution on site
  2. very hot and bad weather most of the time
  3. I do not have long time in the session 4 -5 hours
  4. Sony chip or Kodak ccd noies
  5.  Quality  and supporter ( sbig ,qhyccd)
  6. need very good cooling, me average temperature 37c  ambient in summer
  7. Beginner in astro imaging

i like from all to give me a Suggestions and feedback from there experiences to help me to get the best Choose in long-tram on points, the Budget not more than 2000$ and my setup is:

  • skywatcher neq6 pro
  • gso 200mm f/5 Newtonian withSkywatcher 0.9x Coma
  •  ShortTube 80st guide scope
  • meade dsi pro guide cam

regards

sam

Get a QSI 690 and a set of RGB and NB filters. You may have to sell parts of your  body to afford this but you'd only need to sell it once and you  can operate the camera with the hand you have left over and standing on your only leg.  Bin the colour 2x2 and then add the lum as required.

A.G

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I agree with others, a monochrome camera is 100% the way to go. When would I need a OSC camera? Perhaps when photographing fast moving colourful objects like a comet. In that case I would get out my Canon camera and lens. Monochrome camera's give more comparable sensitivity, better resolution (not really mentioned above) and flexibility for narrowband imaging.

As for the QHY9M, it contains the 8.3 MP Kodak chip which is very popular and well liked, so a good choice. Dare I say the camera manufacturers are not as well known as say QSI, Atik or SBIG. The latter have a long good history of proving excellent products with good customer service. Hence the QHY camera's are seen as a cheaper option as they need to build up their reputation.

Adrian

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I am a great believer in using OSC CCD cameras and have never understood the argument about the difficulty in processing the data produced as I have always found it intuitive and straightforward. However, there are without doubt advantages in using a mono + filter solution in the form of higher resolution images and greater flexibility which is why I use both types.

Me too. Processing mono images takes a heck of a lot longer as there are many more steps (4 lots of stacking, registration, yadda, yadda, yadda). OSC just seems more intuitive, though I am very much a beginner when it comes to narrowband imaging.

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I've greatly streamlined my pre-processing, partly out of necessity, since I sometimes have full nights of data from three full frame cameras to reduce and share with my co-conspirators.

I find one flat per rig (luminance) works fine for all filters.

For each camera I stack in AstroArt using a bad pixel map and bias per rig rather than specific darks, which are time and temperature sensitive. So it doesn't matter what sets I'm calibrating, be it 15 minutes, 10 mins or 30 mins, they all get the same calibration. Not only does this work, it works better than dedicated darks. Obviously you can't mix calibration files across the rigs, though.

A word on scientific imaging; anti blooming gates affect the lineararity of CCD cameras so real scientific imaging requires a non-anti-blooming camera which will produce big vertical bleeds on bright stars. For recreational or aesthetic imaging this can be a nightmare.

Olly

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Hi,

I have two OSC CCDs and a couple of modded DSLRs plus a 314L+ and a 383L+ mono. Calibrating and stacking an OSC file is a much time consuming affair and a real test of my computers resources, mono seems to be a lot quicker. If you just keep to a specific set of filters and perhaps just a couple of scopes and FF/FRs then I guess so long as the filters are kept clean then a Lum flat will be sufficient to calibrate the data with and save a lot of time in imaging.

Regards,

A.G

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And I've just seen that RobH is selling an Atik 16HR on here for £500. His website will confirm my earlier claim that you can take world class images with one of these and, Rob being Rob, the transcaction would carry less risk than buying a pot of marmalade in Sainsburys...

Olly

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And I've just seen that RobH is selling an Atik 16HR on here for £500. His website will confirm my earlier claim that you can take world class images with one of these and, Rob being Rob, the transcaction would carry less risk than buying a pot of marmalade in Sainsburys...

Olly

That is a nice camera, a 285 chip with cooling and not a bad price either.

A.G

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..............using a bad pixel map and bias per rig rather than specific darks, which are time and temperature sensitive.

Absolutely agree with this although I don't like MaxIm DL's (my preferred software) results with these and I use Nebulosity if I am using this approach. With 'dithering', I still find Dark frames very effective with my QSI 683 mono CCD camera even with auto exposure compensation in use if I don't have a matching dark frame set in my regularly updated 'library'.

Sent from my iPhone from somewhere dark .....

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