Which camera do you suggest ? Celestron RASA 11" V2 · ScottF · ... · 7 · 223 · 0

Hi
I have recently purchased an 11” rasa v2. I am wondering which camera would be best to use with it. I have a zwo2600MC and a zwo2600mm DUO. I have a photon cage on order to help dial in tilt and back focus. I have purchased Baader f2 Ha, Su, and O3 high speed filters to use in the filter drawer. I also have a fast scope dual band filter from another scope that could be used with the 2600mc. Would the 2600 mm duo work well on the rasa? I’m assuming it’s fast ratio and the 6.5nm baader filters would make it workable? I didn’t have much luck using it with 3nm filters.

Hi Scott

I use a 2600mm with my RASA8. Here's a few observations that may help your decision.

• I shoot mainly mono in the city, so being able to shoot discrete filters (Ha/Oiii/Sii) vs a dual band really helps pull out the signal. My data is much nicer with the mono camera than with the OSC.
• I use the Baader Ultra Highspeed (4.0 / 3.5 nm bandwidth) and they work great. So your 6.5nm filters should work great.
• Doing manual filter changes for me (narrowband) is a non-issue, as I usually shoot a single filter for an entire night. So I just put in the filter at the beginning of the night and leave it.
• I REALLY wish I had an OSC for doing broadband targets. Shooting broadband with the mono camera is painful, as I'm swapping filters more often. It's nice to shoot LUM for an entire night, but having to swap RGB filters every few hours (or shorter for stars) is not ideal.

I would ideally have a mono camera (for shooting narrowband) and an OSC (for shooting broadband). That's a future plan.

Hi John,   There are three things you haven't mentioned that will really drive decisions for peak performance.    First is what targets you most enjoy imaging.    You haven't mentioned what Bortle environment you're imaging from either, and that could drive whether you even need filters (unless you favor narrow band & false color).   Finally, you should consider your best & nominal seeing conditions.    All of these variables play into your "best" decision for the RASA11.

For example, I have a RASA11 at a Bortle1 site with good seeing.   I enjoy imaging galaxies in broadband, and generally prefer field sizes in the 1 degree range or smaller (although I do make exceptions for larger emission/reflection nebulae fields (and then use a 2600).    For galaxies/narrow fields, I chose a 183mcPro (since it has smaller pixels that will allow me to get to better resolution vs the 2600).    At highest resolution, you'll want to be sure to dither and drizzle.   The RASA11 is a great telescope for either camera (183, 2600), and I use both.

If you are in a much different Bortle condition, you might need to use filters (whether or not you want to).   In marginal seeing, it wouldn't make sense to use a 183 camera since high resolution won't be available anyway.    If you really only like to image wide fields, the 183 wouldn't be ideal as you would have to mosaic too much. 

Finally, at the RASA11 fast focal ratio, the reason your 3nm filters may not have worked as you wished is likely because they weren't rated for fast optical use.  Some filters will not  handle "fast" incoming light ray angles, so wavelength shifting occurs, resulting in missing the specific bands you were chasing.    You'll want to be sensitive to the specs on your filters to be sure they're rated for fast f/2 use.      CS  Doug

Josh Jones:
I would throw in my two cents here and say that a full frame camera is the top choice with these scopes.  You do throw away a lot of data if you go with a 2600 as mentioned above... but, if you go with the 2600, it's going to be really nicely illuminated and you don't have to deal with much vignetting at this point.  

I would give both a go for a month, see if you like changing filters with the mm camera, and if not, try the MC for a month, I think everyone is different with this, of course monochrome being my personal preference, but maybe I just haven't spent a ton of time with the MC to enjoy the fact I don't change filters   But I honestly just leave a filter in all night and take images.  3 nights and you have a ton of acquisition on any target across 3 filters.  I guess that depends on your location as well right?

I also did a image analysis page here:  https://asgastronomy.com/special-rasa-optical-train-setups/  You can see full framers work really well on these... but mosaics with these scopes is really a strong recommendation as well.  You can grab these amazing 2,3,4,5,6 panel mosaics on targets that just would take forever on other platforms.

For filters, I used to use 3nm filters, now I use the astronomik MaxFR 6nm filters in Ha, Oiii, Sii and get much better results.  Let the light in    and the amount of light you gather with f/2 really makes up for any contrast differences you may get with 3nm filters in other platforms.

but to your question on cameras, use what you got and I say give them both a try for sure... monochrome will get you better end results slightly, but might be more enjoyable to you with color cam.  It's all about the smiles per image factor.

Yes, like all things astro, there are pluses and minuses to every decision. I am in Bortle 5 and my seeing conditions are rarely good. I am tempted to shoot OSC because I have little chance of using three filters three nights in a row. More likely it will take 2 weeks or more the way my skies are lately. Summer time is problematic with wildfire smoke interfering with the few clear nights I get. I've come to the conclusion that the RASA will be good for nights when I can only count on 3-4 hours of clear skies. Usually, I wouldn't set up for that amount of time, but the RASA will collect a lot more light than my other scopes.