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colinsk
Pooh-Bah
Reged: 01/17/08
Posts: 1207
Loc: CA
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I can think of two reasons that it may not be as good as a nighttime filter for nebula. One is the transmission of a h-alpha solar filter is theoretically between 5% and 85% of the H-alpha line. I have not measured any but I would be surprised if any were over 50%. Although if money were no object one could be designed.
Also, even fast moving solar materials are blue shifted out of the narrow passband so if there is any significant relative motion it could easily be blue or red shifted from view. A spec quoted for solar viewing is you will find h-alpha detail 2A from center in the blue and .5 from center in the red.
I could be totally wrong about this, but when I got my "nebula filter" from Lumicon, 15 years ago or so, the idea was it removed the lines caused by streetlights leaving some important emission lines. I think OIII and H-alpha were among them. And with my filter I have noticed no benefit when in a dark sky location however in my backyard in the middle of a small city I find a large benefit.
Now I have read of astronomers using monochromators to study important aspects of distant objects. Many of these monochromators are etalon based so it could be that there is a good use for a h-alpha filter if you had a very large amount of aperture.
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Mahalo,
Colin Kaminski
Coulter 10.1" Dobsonian
PST
TV-76/Baader White Light Filter/LS50F/BF1200
LS60T/DS50/FT/BF1200
DSM
LXD-75
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moron392
scholastic sledgehammer
Reged: 08/20/07
Posts: 808
Loc: Charlotte, NC
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what about 'tuning' the filters as well as using an energy rejection filter???
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"If you've done something right, people won't be sure you've done anything at all."
http://www.freewebs.com/moron392/index.htm
60mm meade ngc60 refractor.
Meade 70AZ-TR (short one)
50mm homemade refractor (occasionally with a solar filter)
starblast4.5EQ
6mm,15mm expanse eyepieces
9mm meade Mh eyepiece,17.5mm Meade MA
nikon 7x35's
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colinsk
Pooh-Bah
Reged: 01/17/08
Posts: 1207
Loc: CA
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The red continuim can be a very good place to look for granulation on the photosphere. This is not h-alpha viewing which looks at the chromosphere! The set up is a normal whitelight filter with a 7nm or so H-alpha filter. See this thread:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/2547756/page/0/view/collapsed/sb/5/o/all/fpart/1
Very nice work!
--------------------
Mahalo,
Colin Kaminski
Coulter 10.1" Dobsonian
PST
TV-76/Baader White Light Filter/LS50F/BF1200
LS60T/DS50/FT/BF1200
DSM
LXD-75
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mischief
journeyman
Reged: 04/26/08
Posts: 7
Loc: Northern California
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As a prospective solar observer with a Lunt LSTB600 on order, I want to thank all of you for the terrific information on solar observing. I know a little about the electromagnetic spectrum but these posts really added to my knowledge and greatly needed by me and helpful to me. Thanks very much.
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