Combining mono CCD and DSLR data

[angusb1]

I have an Atik 16HR mono CCD and an unmodified Canon 20D and would like to use them both at the same time to produce colour images. How much data will I need from each? For example if I was to get an hour's worth of luminance data from the CCD, how much Ha data from the CCD and how much RGB data from the DSLR will I need to produce a colour image?

I have also thought that I could piggyback the CCD with a 200mm lens on top of the 20D with a 500mm lens to give almost the same FOV so I could collect data from both at the same time. With a 500mm lens on the 20D I get a FOV of 2.58° x 1.72° and a resolution of 2.65 "/pixel, and with a 200mm lens on the CCD I get a FOV of 2.57° x 1.92° and a resolution of 6.65 "/pixel. Is it worth mixing these different resolutions or would I be better to just collect a mosaic using the CCD of the area and then another set of single shots of the whole area of the mosaic with the 20D using the same lens?

[Psychobilly]

What software are you going to use to do the combining... I know other apps can do it but by far the easiest to use is Auriga Imagings Registar (not to be confused with Registrax)... not cheap but simply superb at combining data from just about any combination of sensor and scope/lens...

Billy...

[roundycat]

received wisdom says you should be using the system with the worst resolution for the colour data, not the other way round. Sounds to me as if you would be better off doing the whole thing with the Canon as the lower res of the CCD set-up will degrade the result quite a bit. Think of it as nearly x3 binning and you will see what I mean.

Dennis

[angusb1]

What software are you going to use to do the combining... I know other apps can do it but by far the easiest to use is Auriga Imagings Registar (not to be confused with Registrax)... not cheap but simply superb at combining data from just about any combination of sensor and scope/lens...

Billy...

Haven't got as far as which tools to use, will have a look at Registar.

received wisdom says you should be using the system with the worst resolution for the colour data, not the other way round. Sounds to me as if you would be better off doing the whole thing with the Canon as the lower res of the CCD set-up will degrade the result quite a bit. Think of it as nearly x3 binning and you will see what I mean.

Dennis

I had thought maybe I should use the same lens to get all the data as I guess it is the luminance data that gives the image its detail so I'll get luminance and Ha using the CCD first and if I get time I'll add colour data from the 20D afterwards.

Thanks very much for the advice. There is an outside chance I may get to take out the new kit for a first light tonight. Fingers crossed......

[ollypenrice]

I agree with Peter and Dennis. The whole point of the CCD is to boost resolution so don't use it in a shorter FL lens than used for the colour. Just accept that the CCD has a small chip and work with that. Use registar to align and crop the colour data to fit. I think you will need about the same of each, but you can experiment. In part it will depend on how you apply the luminance...

Once the images are aligned and cropped you could convert the colour image to LAB colour in Ps (Image- Mode- LAB colour)

Split channels. Merge channels, but when asked by the dialogue box put the CCD luminance into the l channel and discard the colour image's lightness channel.

That is one way.

Personally I would get a filter wheel and Baader LRGB filters and do it all with the wonderful 16HR because I doubt you will get much star colour in the DSLR. Again I could be wrong. It will be good to see how you get along with this. (I do something similar with mono and OSC CCD cameras but it is usually just Ha that I add from the mono rather than luminance.)

Good luck. Hope the weather holds for you! Very iffy here this week.

Olly

[angusb1]

Thanks Olly. I got a filter wheel with the Atik but need to save for a couple of months for some filters .

I thought in the meantime I could use the 20D for some colour data and I'd like to try the way above but can't stretch to the proper version of Registar and the trial version is save-disabled.

Do any of you know of a free or trial version of software that will do the registration, would DSS do it? I have Photoshop but nothing to register/stack with.