Thinking of ordering the 8" RASA but reading through the Bintel information on this scope made me realise it may have narrowband filter problems. Running at f2 is a big plus for narrowband, but the restrictions placed on the little RASA may make it impossible. From what I can gather in my reading the 8" RASA has a 46mm optical window ahead of the camera, and this optical window can be replaced by the special light pollution (CLS) type filter that Celestron is offering for this scope. I am not sure if narrowband filters can be used, in addition or in place of, the optical window, due to the sensitivity of the focal length of the RASA. Obviously, adding a narrowband filter between the optical window, say to the front of a CMOS camera is going to alter the focal length slightly, but is it that touchy? Further, the restrictions on cameras that can be used, mean that backspace to the sensor is very tight. My ASI1600MM-C, without the filter wheel obviously, might be ok, but i need to either be able to place filters ahead of it, or switch to OSC.
https://www.bintel.com.au/product/ce...v=6cc98ba2045f
Edit: I have found the Starzonia Filter Slider for the RASA 8,
https://starizona.com/store/starizon...a-8-zwo-cooled
However, the spacing and addition of another bit of glass still exist. Baader makes a 2" f2 set of narrowband filters, but allow another $1000 USD for those. That factor alone may push it out of my reach financially.
Is anyone using a RASA 8" for narrowband? Or have any comment of filter use beyond the CLS special?