Thanks, Cliff. I kept finding solar interesting, so I've built an alt-az mount that points at the sun continuously, with the goal of capturing sunpots moving over time. Unfortunately, we've been in a bit of a solar minimum for a while, so there isn't much to see. But it's been a great maker project. H-alpha is one of the next things I want to try.
Our H-alpha filter was a "quartz birefringent monochrometer" -- it used a stack of calcite & quartz polarizing filters to get 2 or 3 angstrom bandwidth. Had to be temperature controlled and treated with white gloves. But oh what views of prominences!
ps - we used to call the entrance pupil on a spectroscope a "dekker" because you could choose different slit-widths. I remember being praised by a real astronomer (Helmut Abt) for knowing what this was...
