Colour CCD?

[Astrosurf]

Because of my poor health I'm not always able to spend hours imaging, so just tend to do Ha. I want to take RGB but don't have the staying power. I'm seriously thinking about using my DSLR for colour but it has its issues. I might consider getting a cooled colour CCD. I'll even consider a bank loan! What cameras would you recommend that aren't too pricey? 

[geordie85]

I'm assuming you have a mono ccd already as you say you usually shoot in Ha? If your going to get an OSC ccd then why not get it the same as your current ccd? It'll be less work during the processing stage.

[LightBucket]

The ASI1600 OSC is getting decent reviews, and the newer AS071 is getting even better, as it is a 14 bit OSC camera with APS-C size sensor.

But from what I have been told the best OSC CCD is the SX M25c large format camera.... it that comes at a hefty price, there are two on the bay at the moment, one is the slightly older model at around £1000 and the other the newer smal,regards Version at £1400, I might add they are nothing to do with me, I just keep my eye out, as I am looking myself for a CCD camera.. 

[ollypenrice]

I ran OSC and mono Atik 4000 CCDs for a while. In the end I went for two monos because I found the OSC pretty slow, especially on faint targets. I didn't find it easy to process OSC data either. I believe Sara found the same thing when she tried OSC. I think part of the problem is the incorrect colour balance, with twice as much green as red or blue. (This makes sense by day but not for AP.)

If you have an electric wheel and set it to scroll R - G - B - R - G - B etc, what is the difference in terms of effort at capture? What are you finding hard about it? My concern is that you might not, in fact, find OSC any easier to deal with. OK, ideally people might say you should refocus between colour filters because your optics probably won't be perfectly colour corrected, but you can't selectively focus the colour channels on an OSC either so you are in precisely the same position.

Olly

[LightBucket]

1 hour ago, ollypenrice said:

I ran OSC and mono Atik 4000 CCDs for a while. In the end I went for two monos because I found the OSC pretty slow, especially on faint targets. I didn't find it easy to process OSC data either. I believe Sara found the same thing when she tried OSC. I think part of the problem is the incorrect colour balance, with twice as much green as red or blue. (This makes sense by day but not for AP.)

If you have an electric wheel and set it to scroll R - G - B - R - G - B etc, what is the difference in terms of effort at capture? What are you finding hard about it? My concern is that you might not, in fact, find OSC any easier to deal with. OK, ideally people might say you should refocus between colour filters because your optics probably won't be perfectly colour corrected, but you can't selectively focus the colour channels on an OSC either so you are in precisely the same position.

Olly

I totally get where you are coming from Olly, BUT, for me it is down to lack of experience, time and lack of processing skills, I know that OSC are meant to be harder to process, and that is probably true, but it gives me an image straight from the camera which is great, also I am limited with weight on my set up and taking a filter wheel and filters out of the equation helps, as does keeping costs down. For us newbs it is very rewarding to go outside for an hour or two and come back in with a full colour image, albeit slightly off with the colour balance, I think in the future mono is for sure the way to go, but for now OSC is on my shopping list too...

[LightBucket]

I have a question, as OSC CCD cameras are built for Astro use, why do they put a Bayer matrix in front that consists of 2 green 1 red and 1 blue filter..?.seems stupid to me when they could surely just use one of each colour, or am I being stupid and does it have to be in multiples of 2....  in which case could it not be a pattern of six and have two of each...just a thought

[carastro]

I tried using a OSC to combine with Lum or Ha to save time, but found the OSC extremely difficult to use and after a while gave up and sold it and was glad to get back to my Mono camera.  

I think the big drawback is if you don't have a permanent set up and combined with British skies not enough time to gather sufficient data.  But if you are able to spend one night doing the Ha or Lum and the other doing the RGB or Oiii and Sii, and you can set the camera up the same each time, or better still don't de-rig it if you have a permanent set up, then it is doable, and you can Bin the RGB and Oiii and Sii which also saves time.  

I tend to do what Olly says, and do a sequence on the electronic filter wheel and ask it to capture all filters in rotation, giving more time to the Ha or luminance.  I have recently completed two reasonable images in 2 hours each.  OK 2 hours is not ideal, but it does give a complete colour or NB image.  

A DSLR can also work if you really want to go down that route, as you can blur the coloured data which helps to remove most of the noise and place the Lum or Ha image over the top for detail.  

Carole 

 

[ollypenrice]

52 minutes ago, LightBucket said:

I have a question, as OSC CCD cameras are built for Astro use, why do they put a Bayer matrix in front that consists of 2 green 1 red and 1 blue filter..?.seems stupid to me when they could surely just use one of each colour, or am I being stupid and does it have to be in multiples of 2....  in which case could it not be a pattern of six and have two of each...just a thought

It's simply because astro camera manufacturers don't make their own chips, they take what the manufacturers give them. The signifcant market is for daytime cameras so the chip makers only cater for that. One maker, at least, makes a CMOS chip with LRGB filters rather than Bayer's system. (In his patent Bayer describes the green channel as luminance and the R and B as chrominance, which is OK in reflected sunlight here on Earth.)

Regardng speed, this is an hour of Ha and 20 minutes each of R, G and B, all at F5. Possible in one shot colour in two hours? In my opinion, not a chance. The processing was also done on the fly.

Olly

 

[Anne S]

My MX716 (which has a colour chip in) is CMYG. I wonder why the modern ccd camera bayer matrix switched to RGGB variants. I would have thought a CMYG matrix is more suited to imaging. 

[Astrosurf]

Such great replies! My issue is that I spend most of my precious time on Ha or Lum, wanting to capture lots of data, and only have little time for the RGB (yes, I know I could give more on one night but don't wanna!). I was thinking about adding colour from my DSLR. If I image a neb in Lum/Ha with my Megrez and Atik and the RGB with my Canon on the 200P, the sizes will be similar so not much adjustment. But If I use my 200P for a galaxy, the difference in FOV from each of the cameras will be huge and I'm not too sure about resizing the colour, as to how much detail I'll lose. I know detail isn't too important in RGB, but there's a limit!

I'll consider capturing over more than one night and see how that goes.

I'll give the OSC a miss then!

[geordie85]

6 hours ago, LightBucket said:

I have a question, as OSC CCD cameras are built for Astro use, why do they put a Bayer matrix in front that consists of 2 green 1 red and 1 blue filter..?.seems stupid to me when they could surely just use one of each colour, or am I being stupid and does it have to be in multiples of 2....  in which case could it not be a pattern of six and have two of each...just a thought

Rgb imaging has always confused me (even though I do it) because green is not a primary colour. I've always wondered if imaging in red yellow blue would give a more realistic image. 

I'm sure there's a reason behind it but it's always confused me.

[carastro]

Red, Green and Blue ARE primary colours.  

Quote from the internet: Red, green, and blue light can be mixed in different proportions to produce any other color of light. No other combinations of light can be mixed to make red, green, or blue light so they are considered primary colors. 

Carole 

[ollypenrice]

We humans are trichromats, having three kinds of colour receptors in the eye. I did come across this rather splendid sentence on the net, though...

There is no currently peer reviewed scholarly work that has confirmed the existence of a functional human tetrachromat though they are suspected to exist.

Oh to be a tetrachromat!!

lly

[SilverAstro]

28 minutes ago, ollypenrice said:

We humans are trichromats, having three kinds of colour receptors in the eye.

That would be the Cones, but dont forget the Rods, which could make us LRGB ?

[DaveS]

8 hours ago, ollypenrice said:

We humans are trichromats, having three kinds of colour receptors in the eye. I did come across this rather splendid sentence on the net, though...

There is no currently peer reviewed scholarly work that has confirmed the existence of a functional human tetrachromat though they are suspected to exist.

Oh to be a tetrachromat!!

lly

Since the gene(s) for red sensitive cones are on the X chromosome (Which is why colour-blindness is more common among males), if there is more than one red-cone allele then it is possible for women to be tetrachromic, at least at the red end of the spectrum.

[SilverAstro]

2 hours ago, DaveS said:

Since the gene(s) for red sensitive cones are on the X chromosome (Which is why colour-blindness is more common among males), if there is more than one red-cone allele then it is possible for women to be tetrachromic, at least at the red end of the spectrum.

That is QI, I wonder what the evolutionary spur for that is/was ? 

(PiC asside, I know they often see red but 2 ,   but ,,  ) 

[LightBucket]

Well we no longer talking about colour CCD cameras, you guys have lost me.......so I'm off....

[ollypenrice]

1 hour ago, LightBucket said:

Well we no longer talking about colour CCD cameras, you guys have lost me.......so I'm off....

Just an amusing digression concerning the use of RGB filters...

Olly

[wimvb]

17 hours ago, ollypenrice said:

...

Oh to be a tetrachromat!!

lly

I'd rather be an apochromat.

Seriously though. The discussion so far is about osc ccd, but what about osc cmos? Basically a cooled dslr, reasonable resolution (pixels), sensitive, low noise. And good price/chip size. Should be a viable alternative to dslr. And astro-modded out of the box.

[Andy Mitchell]

23 hours ago, geordie85 said:

Rgb imaging has always confused me (even though I do it) because green is not a primary colour. I've always wondered if imaging in red yellow blue would give a more realistic image. 

I'm sure there's a reason behind it but it's always confused me.

The primary colours, that match the receptors in the human eye, are RGB. However, if you look at an inkjet printer you are dealing with a subtractive colour model. You need just Cyan, yellow, and magenta inks. Each colour absorbs one of the RGB colours only, and allows other colours to be reflected by the paper. So think of yellow as "no blue",  magenta as "no green" and cyan as "no red". I presume when we were all five and our school teachers told us in art class that yellow was a primary colour its a similar situation.
 

[RichLD]

19 minutes ago, wimvb said:

I'd rather be an apochromat.

Seriously though. The discussion so far is about osc ccd, but what about osc cmos? Basically a cooled dslr, reasonable resolution (pixels), sensitive, low noise. And good price/chip size. Should be a viable alternative to dslr. And astro-modded out of the box.

I agree Wim - the QHY183C looks very interesting. 2.4µm pixels, 20 million of them - set point cooling etc all at a very reasonable, sub £1k price point. Should be cracking for some serious widefield action!

[LightBucket]

Or the ASI071c CMOS which looks very good also, 14bit, and more sensitive than the ASI1600....

[ollypenrice]

1 hour ago, wimvb said:

I'd rather be an apochromat.

Seriously though. The discussion so far is about osc ccd, but what about osc cmos? Basically a cooled dslr, reasonable resolution (pixels), sensitive, low noise. And good price/chip size. Should be a viable alternative to dslr. And astro-modded out of the box.

Yes, Alex might well look into these but since I have never tried one I can't give a real opinion.

Olly

[Astrosurf]

I love this thread and the digression is very interesting! I was out last night with the guys and was showing the public my astropics. I must admit, I do love the ones with my DSLR! The red halos on the stars are annoying but I can sort of process them out. A OSC still beckons!

[Astrosurf]

183: https://www.cloudynights.com/topic/548408-my-qhy183c-tests-and-images/