Hi all --
After doing further research and receiving some very helpful advice in this forum, I've decided to get a DayStar Quark Chromosphere as my next foray into the world of H-alpha solar observing and imaging. While I seriously considered trading in my Lunt LS50 to buy a new LS80MT, the cost savings will allow me to keep my LS50 for casual observing and full-disk views. Meanwhile, I'll use the Quark for higher resolution imaging in H-alpha and eventually CaK and white light.
I plan to use the Quark with an Astro-Tech AT102ED refractor, which is a 102mm f/7 doublet with a 714mm focal length. In reviewing past threads regarding the Quark, I came across various opinions regarding (1) whether an ERF is needed at all with apertures under ~120mm and (2) if an ERF is needed, which one is best (e.g., DayStar, Baader D-ERF, etc.). I would rather be safe than sorry, so I will likely purchase an ERF even if one is not "needed," but I could use some help understanding the various options on the market. I am also wondering whether I need to couple the ERF with any other filters such as UV/IR.
Does anyone have any recommendations they can share?