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sctbrd
newbie
Reged: 11/17/09
Posts: 1
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In regards to a double stack Lunt, the rated pass is "<.8 A" and <.5 A".
I have read that 1.0-1.5 A is a normal range for older solar scopes, and this is the most desired range for prominences.
When tuning the double stack, does the actual bandpass go slightly higher or lower? Does the .8 bandpass reduce actual prominence viewing, or is the loss negligible compared to 1.0 to 1.5 A.
I would like to purchase the best range scope for prominences and surface detail, which is why Im eyeing the double stack. I cannot go more than a $2K, so the 60mm is what Im looking at right now.
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BYoesle
Pooh-Bah
Reged: 06/12/04
Posts: 1197
Loc: Goldendale, WA USA
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First, it is very difficult to find a solution to having the choice of two bandpasses you are describing in anything other than what you are looking at, especially in that price range. 0.8 A will be just fine for prominences, and 0.55 for surface detail will be icing on the cake so to speak. The only downside to DS with the Lunt 60 is you loose a little aperture (DS is done via an unobstructed 50mm etalon).
Second, most observers prefer the increased contrast from double stacking to be a better improvement than increasing aperature to the next larger size single etalon. So losing a little aperture for a significant gain in surface detail isn't really a loss at all.
--------------------
Bob Yoesle 
You are a child of the universe,
no less than the trees and the stars...
And whether or not it is clear to you,
no doubt the universe is unfolding as it should.
Desiderata
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brianb11213
Post Laureate
Reged: 02/25/09
Posts: 3271
Loc: 55.215N 6.554W
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Quote:
Does the .8 bandpass reduce actual prominence viewing, or is the loss negligible compared to 1.0 to 1.5 A.
With my (single stack, 0.7A) Solarscope the prominences are not always as bright as they are in a (1.0A) PST but they are actually easier to see because of the higher contrast and relative lack of a "sweet spot". It often happens that, once you've found a prominence, I can brighten it by shifting the tuning a bit.
If I was interested only in prominences I'd far rather have a larger single etalon than a smaller double stack at the same price. If I was interested only in surface detail the opposite would apply. The single stack 0.7A - 0.8A etalon is IMO an excellent compromise as well as being the best value for money.
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Fish
sage
Reged: 10/13/07
Posts: 475
Loc: Norridgewock, ME
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Good evening,
As with many things in life, solar viewing at any given bandpass is a compromise. This is the reason many available Ha scopes and filters have a bandpass around 0.7A - 0.8A.
Solar prominences tend to be at their best at about a 1.5A bandpass. Problem is, the disk is completely washed out by energy from the photosphere at that width. In order to see any disk detail you must get down to about 1.0A or less.
These surface features tend to get better as the bandpass lowers; look through a 0.3A system someday and drool! As all this happens the prominences will still be visible but become quite dim. Below about 0.5A they all but go away.
As an aside, the difference in brightness between solar disk features and prominences is well accommodated by the human eye but not by cameras. This is why you can visually see both features but separate exposures are required for most photographs.
So as you see, there is no one bandpass to give you the best view of both disk detail and prominences. One wants a low bandpass, the other a high one. A filter of 0.7A - 0.8A is a good compromise and does yield satisfying results. As always, aperture rules the game but a doublestack gives you a choice; use both together to reduce the passband and see disk features better or remove the outer etalon and get improve prominence performance.
There's plenty to see no matter what you choose so get on with it and enjoy daytime viewing!
Regards, Marc
--------------------
Goseck Observatory
Kunming 152 f/5.9 & Baader Wedge
Orion ED80 & LS75FHa2/B1200
Meade 102ED & LS18CaKMDd2
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Rat
sage
Reged: 10/13/06
Posts: 215
Loc: USA
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After reading the comments here, I'll would like do a side by side comparison with my Solarmax40 and C102HD/Thousand Oaks Ha setup. I'll assume the latter setup will show prominences brighter and clearer?
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