I can't resist playing with Omega (eBay) filters! Here are two AR shots. I was hoping for sub-Angstrom bandpass with inclusion of the Lunt etalon but it looks to be a couple of Angstroms (reflectivity of the etalon surfaces must really be optimized for H alpha). It was easy to tune the etalon to peak on a single Na line from a lamp but tuning while observing didn't yield any noticeable changes in contrast on the disk. More playing required!
