Wayne, I didn't know you worked at Lunt. It must have been an interesting experience. I think you are probably correct. The difference in price is attractive, though. I imagine if one just wanted a scope to every now and then look at a prominence, probably the TOaks is a good way to go. After I posted my question I looked at Daystar's website. Maybe some of us forget about them. They existed before Coronado and Lunt. At http://www.daystarfilters.com/Quantum.shtml they have a good description of what can be seen at the different bandwidths. They produce a 0.3A unit for a mere $14,000. They still require an f1/30 scope which means focal extenders. It also seems their product has a definite shelf life I am not aware of with the other two manufacturers. For awhile I was subscribed to the Daystar discussion group and there was a discussion about a filter, or something like that, that goes bad over time. Stan On 10/9/2011 12:25 AM, Wayne (aka Mr. Galaxy) wrote: > Benson, AZ 85602 > hm ph: 520-586-2244 Stan, I can't speak to the difference between a TO 0.9A > and a Lunt 0.7A, but I can speak to the difference between non-stacked and > stacked (to give an effective 0.5A bandwidth) 0.7A etalons from Lunt since I > worked for them for about a year and tested them. The difference in detail > and contrast were remarkable, not even subtle. I would suspect it might be > the same difference if it was a Lunt 0.9A compared to a Lunt 0.7A. Seeing > conditions might be the great equalizer, though. If you have a good site, it > would be best to get the better filter. If your seeing is mediocre then you > might be able to settle for the wider bandwidth. It's probably analogous to > the difference between 1/4 wave optics and 1/20 wave optics, but again seeing > equalizes out the difference there, too. Clear skies, > Wayne (aka Mr. Galaxy) > > -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.