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Advice on improving RGB of my LRGB

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#1 oneredpanther

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Posted 05 December 2021 - 03:23 PM

At the moment I'm capturing L on the wonderful ASI1600MM Pro, and RGB on a modified Canon 750Da (that's just where I started, and what I currently have laying around). 

 

The Canon is somewhere between barely adequate and terrible for capturing RGB data. 

 

I want to improve the RGB that I can capture, within the specific context parameters of my environment. 

 

Here's the thing: I live in Denmark and I would say I get between 60 and 100 clear nights per year if I'm lucky. That's not much. 

 

For example right now I've been able to shoot four hours of data in the last five weeks; and the next 10 days is 100% overcast every night. Cloud can persist for weeks at a time. 

 

I also have a rather old Macbook with a limited about of SSD space that means I can stack perhaps 100 images at once before it runs out of working space. 

 

I do not currently have a focuser. 

 

Although I know that simply adding RGB filters to my mono filter wheel would be the best quality outcome, the reality of the situation is that I do not have the reliability of opportunity to gather separate R, G, B data; nor the space the process the mountain of data that it entails. 

 

My gut feeling then, where time-efficiency and ease of processing is key, is to get an additional OSC to perform the RGB function of my LRGB rig. 

 

What would you suggest as a route forwards? 


Edited by oneredpanther, 05 December 2021 - 03:24 PM.


#2 DivisionByZero

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Posted 05 December 2021 - 04:50 PM

I think it would help give you the best advice if you tell us a little more:
1) sky conditions in terms of light pollution,
2) speed/type of your imaging rig, and
3) what's really wrong or going wrong with the 750Da as it is.

My gut reaction without more info is that if you can't get the OSC you have to work, I doubt a new, expensive OSC will change much for you.

Its true that LRGB does take longer to obtain, but it provides a lot of freedom and control on the color balance in the end.

There might be other tricks as well, like splitting your image up and processing as though it were binned. This would allow you to drop one of the green channels (most cameras have two) to balance the RGB better. This approach would only help for some types of problems, though.

#3 oneredpanther

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Posted 06 December 2021 - 03:01 PM

To answer your above, sir: 

 

1. Normally I conduct any RGB work in a Bortle 4 or better environment. 

2. Rig is Redcat 51 (f/4.9 apo quadruplet) on a HEQ5

3. There is terrible colour vignetting (as opposed to luminance vignetting) that is hard to calibrate out; the image always appears muddy as heck; but more to the point I would rather swap one ASI for another ASI than have to disassemble the entire imaging train to take a DSLR on and off. 



#4 imtl

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Posted 06 December 2021 - 04:39 PM

Its true that LRGB does take longer to obtain, but it provides a lot of freedom and control on the color balance in the end.


It is not correct that LRGB takes longer to obtain. When SNR is equal, LRGB is more efficient and could be by a far margin under certain conditions. (LP, object etc)

#5 DivisionByZero

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Posted 06 December 2021 - 09:09 PM

Well, in practice it certainly feels longer as I have to recheck focus for each filter. Its definitely longer for the OP as he has to pull the entire camera off.

The main thing, though, is that I got a lot faster at working once I got my filter wheel. It does save time not moving the camera. The filter wheel plus filter set is about half the price of a new, cooled color camera, and you'll keep all of the flexibility.

Your sky conditions are such that you shouldn't have such a problem with color balance, in my opinion. I would guess vignetting issues are probably closer to the sensor size and your scope. Are you taking flats each time you move the cameras?


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