I own a DS SF70 filter set that I have dedicated to a TV76 with dual speed focuser. In no particular order I can add the following:
-Pairing these filters with a TV76 is in many ways ideal although somewhat overkill in that a decent achromat would likely more than suffice. With a Solarscope supplied adapter, I can screw directly onto the OTA with dew shield retracted. I love the solid and secure feel of this configuration.
-You can reach the tuning rings of both SF70 filters easily with a TV76, even a TV85 put them at an uncomfortable distance for me.
-The SF100 without central spacer constitutes a heroic manufacturing effort but as Bob (and others lucky enough to have used an SF100) points out, thermal stability can be a problem.
-I use binoviewers (Baader Maxbright) for >90% of my visual observing using primarily Pan 24's, Zeiss 25mm equivalent microscope eyepieces, and other 16-18mm simple eps from my collection. Binoviewing is the single most important upgrade once you decide on a filter system and scope, at least IMHO.
-Hard to argue with Bob's comparison of the Coronado 90 and the SF100 although visually I doubt most of us could tell much of a difference at the EP. Sample variability also definitely matters - Bob's Tucson Coronado filters seem to me to be particularly good examples.
-I agree that daytime seeing is more limiting to higher apertures and may not allow you to realize as much bang as you think you'd get at >90mm or so. To me, the SF70 is in the Goldilocks zone for unobstructed etalons or their equivalent.
-The Solarscope filters are "worth it" to me, at least at the 2015 prices I paid when I sent back my SS SF70 to get it DS'd. However, given the cost (relative to Lunt or Coronado) you are in the land of diminishing returns with a Solarscope filter set. A look at Bob's posted images more than drives that point home.
-it isn't all just about aperture when it comes to viewing or imaging in H-alpha. What I am struck by with the Solarscope filters I have used (including an SV50 SS scope) is the on band performance across the solar disc/FOV and the deep black backgrounds. I can't speak to how they compare to something comparable from Lunt or Coronado; I've not had the pleasure of a side by side.
- While I like the SF70 filter set, I still miss the SV50 a lot - its performance was outstanding and it seemed to punch well above its weight class. So, no, it is not all about aperture.
Edited by Doug D., 22 November 2019 - 12:05 PM.