I am a beginner of asto-photography.
Monochrome ccd should take 3X exposure time (RGB) than color ccd. Is it worth ?
e.g. Orion Starshoot v2 color ccd and Orion Deep Space Monochrome image III.
May I have some comments before buying it ?

In monochrome the image is more "true", because with the color image there is a software interpolation of the data to reconstruct each layer (called the bayer matrix). If you want to take more scientifically accurate image data, go with the monochrome. If you want to take portraits of beautiful objects, planets, nebulas, a color camera can do an excellent job.

Color is more convenient. With the monochrome, you have to use seperate RGB filters, and take three sets of images. Then combine them in software. Color is faster (only needs 1 set of images) which is important If the object moves in the sky. A planet may rotate in only 10 minutes. If it moves while you are still imaging, then the perspective is different. You cannot combine the images very well.

Some people eventually end up getting both types of cameras, a color camera for making nice RGB images and a monochrome for special applications, such as narrow band imaging, astrometry, photometry, spectroscopy...

TeleNoob:

In monochrome the image is more "true", because with the color image there is a software interpolation of the data to reconstruct each layer (called the bayer matrix). If you want to take more scientifically accurate image data, go with the monochrome. If you want to take portraits of beautiful objects, planets, nebulas, a color camera can do an excellent job.

Color is more convenient. With the monochrome, you have to use seperate RGB filters, and take three sets of images. Then combine them in software. Color is faster (only needs 1 set of images) which is important If the object moves in the sky. A planet may rotate in only 10 minutes. If it moves while you are still imaging, then the perspective is different. You cannot combine the images very well.

Some people eventually end up getting both types of cameras, a color camera for making nice RGB images and a monochrome for special applications, such as narrow band imaging, astrometry, photometry, spectroscopy...

I believe in reality a One shot color is closer to the true color since the color data it collects through the color matrix is color that already has to be there. How intense each color is in the final image is up to the photographer processing the image. With a monochrome camera using color filters you are choosing which colors and the amount of exposure for each. The color you see in those astroimages is typically the artists rendition.

For scientific purposes RGB or Narrowband line filters are used with a Monochrome CCD, then each channel has to be Digitally Developed after calibration and stacking, then assigned their color (colorized) before combining each channel for further processing into the final image. For RGB images you obviously assign each color accordingly, that doesn't make the image true color. When using narrowband line filter there is no strict set of rules however there are a couple generally accepted color pallets in use. One such color pallet is the HST(Hubble Space Telescope) pallet. Basically speaking the colors used for scientific purposes are so that the scientists reviewing the image can study the structure and distinguish the differences from one emission source to the other. It's not necessarily the real color, it's for scientific purposes only.
For example in a one shot color image Ha regions are usually red and is why you often see red as the dominant color in many astroimages of nebulae. However, using the HST pallet Ha is assigned the color Green, and SII is red while OIII is blue.
The other widely accepted pallet is the CFHT(Canada France Hawaii Telescope).

To learn more on that you can refer to Richard Crisp's article on Narrowband imaging.

http://www.narrowbandimaging.com/images/Crisp_emission_submit_final_release.pdf

One shot color is more convenient and easier. You don't have to worry about calculating the most optimal timing/exposures for each channel, you don't have to worry about (DDP)Digital Developement Processing after calibration and stacking of each individual channel before you can combine and process into a final image.

TeleNoob, Tks for telling me the difference between two ccds.
Especially color ccd is for fast moving objects :)

Tim, Tks for rich resource.
Astronomy really is not that simple than we thought but this is also the interested part.
Tim, you told us you did not have your own personal website before.
Do you have now ?

Tks a a lot lot :)
 

Ming:

Tim, you told us you did not have your own personal website before.
Do you have now ?

Tks a a lot lot :)
 

No I don't, there are already plenty out there.

Those fast moving objects would only include Planets, Comets, Meteors, Iridium Flares, ISS, and HST, Not DSO's.
For the planets you want to shoot at a fast frame rate and is why most people use Video from a Web Cam or similar camera. For Meteors a DSLR with a short focal length lens is probably better than most CCD cameras or any camera for that matter attached to a telescope.

Tim, I am too beginner for high end ccd (above $2000).
Do you think that Orion Deep Space Monochrome image III is enough for us to "play".
You have DSI II color CCD. Do you "satisfy" ?
I am you fans. Pls think it again to make your website. :)

Ming:

Tim, I am too beginner for high end ccd (above $2000).
Do you think that Orion Deep Space Monochrome image III is enough for us to "play".
You have DSI II color CCD. Do you "satisfy" ?
I am you fans. Pls think it again to make your website. :)

I don't do any imaging with the Meade DSI II C CCD camera. I tried many times and no matter what I did or what telescope I used it on I didn't like the images that came from it. Now it's primary use is as my Guide Camera for auto-guiding while I do my imaging with a different camera. The Meade DSI makes a good guide camera.

I really can't answer your question about the Orion Deep Space Monochrome Camera. They're probably pretty good entry level CCD cameras at relatively low costs. However, keep in mind, you get what you pay for!
I personally don't use one, never have, nor do I really care to. I've seen reviews and results that show the Orion CCD cameras are comparative to the Meade DSI CCD cameras. If I ever decide to get another purpose built CCD camera it will probably something other than Orion.
If this weather pattern doesn't change I won't be wasting my money on any new astronomy equipment.