Mono Versus Colour

[Colan]

Hi

Not in a position to buy one yet but would eventually like to get a proper astro Cam.

I am a bit confused with the whole Mono v Colour situation.

What are the Pros and cons?

And also what is meant by a single shot cam?

[steppenwolf]

A single shot colour CCD is actually just a mono CCD with a thin layer of filters coating the individual pixels, laid out in a specific pattern known as a ‘Bayer Matrix’. In this matrix, there are repeating groups of four filters arranged in a square grid - one Red, two Green and one Blue filter in each square block. The reason that green was chosen as the ‘duplicate’ filter was to mimic the human eye's greater green light resolving power. Colour data is coded into this matrix when the contents of each pixel are read from the sensor. During processing, a special algorithm is used to decode the Red, Green and Blue data to construct the colour image. This decoding procedure is called de-Bayering and is carried out externally by special software supplied with the camera or by a third party program.

The advantage of a mono CCD camera is that it is more sensitive and, theoretically, has a better resolution that a one shot camera (OSC) and it can be reliably used for narrowband imaging. It will al so take great mono images. The disadvantage is that to get colour from a mono CCD you have to take a series of images with Red, Green and blue filters as well as a luminance (unfiltered) image and then combine these together to form an LRGB colour image.

An OSC on the other hand produces colour images in 'one shot'!

[Colan]

Thanks for reply, all is now clear :-)

So in fact as a beginner I am probably better off going for a colour cam than a mono one, do you agree?

Thinking to avoid the whole Filter business till I am a bit more experienced.

[centroid]

I think Steve has summed that up very nicely.

The main reason for my using an OSC camera, and I have tried mono and LRGB imaging, is one of time.

The number of good nights that we get in this country are painfully few.

My interest is in colour images, and for me, the ability to capture both the luminance and RGB in one go, outweighs the benefits of mono sensitivity, and better narrowband imaging.

IMO, the mono camera, and RGB filters will always produce the better image, especially as the luminance can be captured in narrowband. However, all of the pictures on my website, and Steve's I believe, were captured with an OSC camera. While not perfection, I'm pretty much happy with them.

So, the 'bottom line' is, its all down to personal preference really.

Dave

[steppenwolf]

I think that would be my advice as this would get you up and running with the greatest chance of early success. Many imagers only ever use one shot cameras and the results speak for themselves. In an ideal world, you want BOTH but let's not get too far ahead of ourselves!

[Helen]

....but just to put the other point of view.... mono are easier to process and so I'd say start with a small mono camera. That way you can get some decent results straight away and learn the processing black art.

Helen (who is about to buy her first OSC camera!)

[steppenwolf]

Helen (who is about to buy her first OSC camera!)

[ollypenrice]

Hi,

I started imaging just about 18 months ago and originally tried to order an OSC camera. My advisors seemed to imply that mono would have been their choice but I opted for a fairly costly SBIG OSC. However when it turned out not to be available I went for an Atik 16HR mono and filters and I'm now very glad I did. I think OSC seems easier but is it? The processing can be tricky and the problem of light pollution, if you have it, is probably harder to deal with in colour.

As for the speed argument (related to infrequent clear UK nights) I might also put the case for mono. If you don't have many clear nights anyway, and half of them are going to fall in the moonlit period, you want to be able to do narrowband imaging on those nights - yes? In which case a mono is far better. Only one pixel in four on a Bayer martrix is sensitive to Ha, for instance.

I'd say get in there from the beginning with mono. If a camera with the Sony 285 chip is within your budget then go for it. It is SO easy to use. No darks and so fast...

This forum is one of the friendliest places on earth and all the help you need is at hand.

(My comment on light pollution is not empirically based because I don't really have any so others might widh to speak with more authority.)

Olly

[psjshep]

Over the many years I have been imaging (now over 10), I have been down both routes.

The main piece of advice I would give is go for Mono to start with - This gives best resolution & signal for the exposure and the processing can be much more forgiving. It is def. easier to process mono images & I think there is a pleasing grace & simplicity to black & white images.

You could then move onto colour imaging with a one-shot Colour later.... If you do Luminance-Red-Green-Blue (LRGB) with filters, as has already been pointed out, you will probably need a long session or multiple nights.... NOT often possible & the processing is tricky.

This answer to the question does also depend on your setup. If you are pier/obsy mounted, then either route *could* work fine. If you setup each time, then as has been stated already, you don't get long amounts of time to shoot.

I did b/w then OSC - I am NOW looking at moving back to b/w and narrowband (OIII, SII, Ha)

just my peneth worth.

Phil.