RGB Stars- OSC vs Mono

[AdamJL]

Hi all

I recently got my first mono camera and now am planning first light. I want to shoot narrowband with RGB stars, and the idea was to shoot my narrowband channels first, then do 60-90s exposures per colour channel to just get star colour.

But that got me thinking... my two cameras are the same sensor. One is OSC, one is mono. Besides having to switch cameras, and make sure spacing is accurate between cameras, what are the pros/cons of using the OSC just for RGB stars?
I mean the biggest pro I can see is less calibration frames and calibration workflow on the PC (one stack of RGB vs three stacks for the channels in mono) but is there any other benefit?

Cheers

[Nikolas]

Try it and see

[DJT]

Hi Adam
If you have a permanent/semi permanent setup your biggest issue will be having to take a new set of flats every time you swap out cameras unless you intend to take flats at every imaging session. The idea of having a library of flats becomes redundant.

If you break down your setup every night maybe it’s not such a big deal.

Just a thought. (0.02)

David

[JohnH]

If backfocus allows a flip mirror would allow both cameras to be fitted...

[AdamJL]

Thanks all for your input.

@John, I had no idea those things existed! Cool :)

In the end, I was actually forced down the path of using my OSC for star colour.
My filter wheel wouldn't connect properly when I was setting up the camera for RGB, so to make sure I didn't lose a precious night, I just switched over to the 2600MC.

I'll hopefully have an image to share in the coming days if it worked.

[PRejto]

I tried doing this for a while though not with narrow band. I shot a lot of luminance (KAF8300 CCD) and then used a one shot camera for RGB (Sony ICX694). The problem I had was that my stars from the one shot were larger and wouldn't combine very well with luminance. Perhaps it was the different CCD sensors, or perhaps the lower resolution of the one shot camera, or it may have been poor processing technique on my part. I gave up the idea after trying a few times and being unhappy. Hopefully your trials go better!

Peter

[ChrisV]

Sounds like a hassle swapping cameras. Changes in rotation, etc.

[SB]

Hi Adam,
I have been having the same thoughts about swapping cameras. I originally planned to go this way but have shelved the idea. Reasons being:

* I don’t do flats as I don’t take my image train apart and there is very little vignetting with a 1” sensor. Swapping cameras would risk dust introduction.
* swapping cameras would inevitably cause image train rotation and that would mean compulsory guide re-calibration.

So I’ve decided to stick with just the mono camera in place. This wasn’t my original plan but as this hobby evolves I find surprises and re-thinks along the way!

SB

[gregbradley]

You could try marking the exact position of the camera with some electrical tape cut to form an arrow. That would most likely work.

Greg.

[AdamJL]

Hi Peter. Thanks for your input. I actually ended up trying it out recently, and whilst I didn't get the results I wanted, that was more from a poor processing technique, rather than the hardware side which was easy to setup.
That said, I only did it because my mono filter wheel wasn't working so I just swapped the camera out for the ZWO.



Rotation is actually really easy to figure out. I use NINA and it got me back on the right rotation within 2 minutes.



Hi Chris

Valuable info, thanks! The flats thing is indeed a good point, though I guess you're taking even less flats (if you're breaking down the setup each night) since you only take them once for the camera rather than for each colour filter)

[SB]

Hi Adam,
I take the whole scope and gear off the mount indoors, carry the mount outside (after taking the counterweights off!), then place the scope onto the mount and polar align etc so I avoid having to take the image train apart. When I travel I take the scope off the mount with the image train intact and place it in a Geoptik bag and it goes on a sleeping bag on the second row seats with seat belts round two pillows! Consequently I don’t get dust (well very occasionally)!

Chris