I'm at the "want it all, but no way I have the budget for it all" situation that most of us are probably in.
I really want a RASA because I really like to dig deep but also want to go mono. ..and I have neither a mono cam, nor a RASA.
I also don't like the current affordable mono cams (amp glow and tiny pixels with the 183, and microlens reflections with the 1600).
So as a stepping stone, waiting for funds to go mono and RASA, thought I can almost get there.
So...gasp...use narrow band on a OSC with the RASA. Yes, not efficient in the slightest, but I think the efficiency with the RASA is close to a typical refractor with mono. And being that I already have the ASI533, I can still go full on light bucket with the OSC when I want till I can get a true mono cam.
Does the math roughly check out?
Currently using an SV80A @~450mm f/5.6 with the FF/FR (f/7, 0.8x).
RASA throughput would be 5.6^2/ 2^2 = 7.8x faster photon collection.
Lets just pretend the RASA at 400mm is about the same as my current 450mm refractor.
But the RASA has a central obstruction, so it is actually [(203/2)^2 - (93/2)^2 ]/(203/2)^2 * 7.8 = 6.2 x faster photon collection.
OSC only has (at worse) only 1/4 of the pixels dedicated to a specific filter color which is about the same factor as the RASA efficiency increase
Rasa is still faster at photon collecting but not but much, and that difference probably will be eaten by the double filter loss.
So my current refractor with a mono camera and narrowband filters will be similar to the RASA with with OSC and narrow band filters...with the bonus of potential higher spacial resolution should seeing allow.
Does that check out? Again, this would only be a temporary solution till I can also get a mono cam I'd be happy with to pair up with the RASA.