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Dan McConaughy
super member
Reged: 11/11/06
Posts: 109
Loc: LA
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Hello
Last night it was partly cloudy and I had some nicer views of Mars when there were clouds in the way. Consistently over years, my best views of Mars are through clouds, which cut the glare. I've tried a neutral density filter (a Baader 23% pass through and multicoated), but it just doesn't seem to do as well as clouds. I've had this problem also with a D&G 8" refractor and C14; so it's not just because of the 16" aperture.
Do any of you have any suggestions?
Thank you.
Dan McConaughy
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16" F/12 R-C with optics figured by Paul Jones mounted on Byers Research Grade Series II mount with Gemini GOTO housed in 11.5' Sirius Observatory.
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 6207
Loc: Inner Solar System
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Dan,
It's not a problem, it's a bonus. It's the same for everyone. I've had my finest views of Mars and Saturn through cloudiness or fog. It's a natural glare filter, far better than anything you can put in your optical path.
All the old time observers knew about it; you can find routine references to the effect in the books of Antoniadi, Pickering, Flammarion, etc. It's just an extra plus when you get these conditions.
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- Rick
14" LX200GPS
Dyslexics Untie!
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3523
Loc: Doylestown, PA
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Yep me too. My best observations of Mars are also through thin clouds. Not only is the brightness and glare reduced but the seeing seems to be better when clouds are overhead.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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Dan McConaughy
super member
Reged: 11/11/06
Posts: 109
Loc: LA
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The question is, what is the best way to filter the light to imitate the cloud filtering? As I mentioned, the ND filter doesn't really do it.
Any opinions on polarizing filters? I haven't used them fearing the impact of 2 optical elements in the lightpath. Also, I haven't seen that anyone makes them to the same specs as say Baader does, when it makes its filters.
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16" F/12 R-C with optics figured by Paul Jones mounted on Byers Research Grade Series II mount with Gemini GOTO housed in 11.5' Sirius Observatory.
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 6207
Loc: Inner Solar System
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No opinions here. I have an old (no-name, Japanese) variable polarizing filter, but I don't use it much for just that reason. I've never found any filter that worked nearly as well as clouds.
This sounds like an opportunity for someone to invent a really useful planetary filter!
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- Rick
14" LX200GPS
Dyslexics Untie!
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Dean Norris
professor emeritus
Reged: 11/05/08
Posts: 561
Loc: Santa Cruz, Ca
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Dan, Make yourself an apodizing mask. Here's a link. http://csastro.org/category/articles/
On most nights I find this to be helpful.
Dean
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1971 10" Cave Newtonian F/6
MoonLite CR Focuser Telrad Finder 9x50 SV finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, 4mm ortho, Meade 2x Barlow
7x50 Binoculars
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