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bigbeck
scholastic sledgehammer
Reged: 08/13/08
Loc: Trenton, NJ
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Re: Larger aperture, What to expect?
[Re: OvidiuDanut]
#2608458 - 08/27/08 09:37 PM
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Well, i have a bit of the same dilema my self. Although i do have a backyard, i live in a orange area with heavy light pollution. In most nights of the summer i can barely glimpse naked eye the components of Lyra or Hercules. The 8"Dob i purchased 3 months ago is showing me so little of what i've expected. I'm not blaming the dob, im blaming the light pollution for that. I can hardly see something like resolved stars in M13 (but very dim) and the Ring Nebula for instance is so poorly represented... I know that going to a dark area could be the answer, but finding the time to do that is very difficult... So know i find my self at a crossroad... Should i get a 10" er Dob or should i take the refractor way?
More than a 10 incher Dob is not acceptable because of the bullkiness; i carrie it assembled and i m positive that a 12 incher sonotube is more than i can handle... So what could be the answer for me?
The first scope was a 70mm refractor and i bought the 200mm gun on the thought that i could get good views in my LP area, but i guess i was wrong because all i get are DSO's at the threshold of visibility... Now i'm thinking that instead of the Dob i should buy a pretty 120mm refractor like an Omni XLT that could give in the city nice looks of the planets, the moon, open clusters, double stars, variable stars and maybe few nebulas and in a trully dark sky i would get very good views of DSO's either...
Help me!!!
I don't think a 10" will do much good for you. I live in a a "red"light pollution area and don't even bother trying to look at dso's. Planets,yes.
A 20 minuite ride from me is an orange light pollution site. From there I can see about 20% of the Milky Way at zenith,naked eye. Also M13 and M17 look very good through my 8" dob.
If I take a 45 minute ride I'm in a yellow obsevering site with the Milky Way visible from horizon to horizon. The views of The same DSO's are stunning compared to the orange site. Even my 5" reflector gives me pretty good views. Nowhere near as good as the 8" dob,though.
I'm thinking that you're not in an orange LP zone.
Darker skies would solve your problem. It's critical for DSO's. Don't matter for planets or the moon.
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Starkler
scholastic sledgehammer
Reged: 11/04/05
Loc: Australia, Melbourne
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Re: Larger aperture, What to expect?
[Re: bigbeck]
#2608587 - 08/27/08 10:47 PM
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I wish the fallacy of light polluted skies favouring small scopes would be put to rest once and for all! 
I say the opposite is true in that LP hampers small scopes more than large ones. With a larger scope you still have the option of cranking up the magnification to mitigate the effects of LP before running out of light with a small exit pupil in an environment where proper dark adaptation isn't achievable.
No scope will pull low surface brightness nebulae and galaxies out of the LP murk, but a larger scope still gives the opportunity to see smaller high surface brightness objects like planetary nebulae, and will always better the small scope on their usual targets of lunar, planetary and star clusters.
I maintain that small scopes are rendered particularly useless in comparison to larger ones in light polluted conditions.
What small scopes do best is widefield viewing of rich star fields ie sweeping the milky way, which just wont work where there is LP.
/rant
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Lee Jay
Pooh-Bah
Reged: 02/27/08
Loc: Westminster, CO
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Re: Larger aperture, What to expect?
[Re: Starkler]
#2608619 - 08/27/08 11:10 PM
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I wish the fallacy of light polluted skies favouring small scopes would be put to rest once and for all!
Why? It's true! Smaller scopes are easier to throw at street lights!
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Meiling
super member
Reged: 08/25/08
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Re: Larger aperture, What to expect?
[Re: Lee Jay]
#2612954 - 08/30/08 03:42 AM
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Have my 10-inch homebuilt (by someone else) dob for 1 month now and having used almost exclusively 70/80 mm refractors it just blows me away. Last night Vega was almost intolerable for me when it entered the FOV. The ring was a very clear and well-defined ring instead of just a smudge.
It all makes sense, aperture rules and rules big-time. Even in light-polluted skies aperture wins. You get more resolution, more detail and brighter views. Because everything is bringter you can fight the LP because you don't run out of light so easy. Magnification is made possible by 1. the amount of light to play with (aperture), 2. quality optics.
Anyway. A 10-inch is a perfect size, especially when you buy a Zhumell for the optics and the focuser, and then build an Obsession-style trusstube dob from it. A buddy did it and then sold the scope to me. He now has a 12-inch in the works based on the Obsession-compact.
Edited by Meiling (08/30/08 03:42 AM)
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Franklink
sage
Reged: 07/19/08
Loc: Somewhere Dark
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Re: Larger aperture, What to expect?
[Re: Meiling]
#2613110 - 08/30/08 09:13 AM
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Thanks for the great replies!
I hope to buy that zhummel by november!
can't wait!!
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