What's best for light poluted skies?

koputai (Jason) · #1 05-03-2008, 05:48 PM

I currently have an 8 inch Dob, and am pleased with its performance. However, I'm not happy with the performance of the skies around here, being in suburban Sydney and all. Ideally I'd like better performance on DSO's and star clusters.
Does bigger aperture give better performance in light polluted skies, or do you just get more light pollution? Is money spent on aperture better off spent in other places under such conditions? Like maybe filters, an equatorial mount, or some other kit?

Cheers,
Jason.

Matty P (Matt) · #2 05-03-2008, 06:03 PM

Jason, I know exactly how you feel.

My skies are fairly light polluted because just down the road there is a oval with a whole bunch of flood lights that are around the brightness of the Sun.

Also did I mention there is a street light?

Anyway, it is not all is bad. I am lucky that the flood lights are switched off.

There are light pollution filters that claim to reduce light pollution and inhanse contrast. These may help you.

Skyglow filter
http://www.optcorp.com/product.aspx?...w=skyglow&st=2

goober (Doug) · #3 05-03-2008, 06:09 PM

You'll get a ton of replies, I'm sure.

I went from an 8" to a 12" dob for observing from Melbourne. Can't say it made great gains in terms of DSO punch.

§AB · #4 05-03-2008, 06:16 PM

I've heard nothing but contradictions regarding increasing scope size and sky conditions.

I've heard that upgrading a couple of inches makes a "great difference" in suburban conditions, but barely any in dark skies while I've also seen people say the opposite, i.e. no improvement in suburbia, but a world of difference in dark skies.

Bottom line is, larger apertures will show you more regardless of the level of light pollution.

wavelandscott (Scott) · #5 05-03-2008, 06:55 PM

There will never be a subsitute for dark skies...

Increasing aperture should aide in the fight against light pollution...
More magnification should aide in the fight against light pollution...
Some filters can improve (marginally) the fight against light pollution...
A light shield/screen can aide...
Keeping your eyes dark adapted can aide...this to me is one of the most overlooked factors in considering light pollution...if it is bright enough to not allow your eyes to become dark adaptation then are fighting a battle that will be ahrd to win.

I have tried many of the above and while they all "help"...unfortunately, I think the best investment is in petrol to get out to a darker spot...

Starkler (Geoff) · #6 05-03-2008, 07:03 PM

In general, the smaller the scope, the greater the extent that light pollution renders them useless for dso's

In dark skies, the 30mm finderscope on my 5" newt will outperform my 250mm newt at home on low surface brightness objects.
There is no substitute for dark skies, and to answer your question your money is better spent in getting your scopes to some place dark.

rmcpb (Rob) · #7 05-03-2008, 07:03 PM

The best idea for you would be to tolerate the light polluted skies but escape each new moon weekend to a dark site and join the other observers there. Depends in Sydney which way you go but there are plenty of groups that meet.

koputai (Jason) · #8 05-03-2008, 07:19 PM

Thanks for the replies guys.
Yes, I realise dark skies are best, and I get to Mangrove Pony Club occasionally.
What I'm after though, is better performance at home, so I can get outside and have a look more often, not sit inside and wait for one night a month away from home.

Cheers,
Jason.

Starkler (Geoff) · #9 05-03-2008, 09:26 PM

Quote:

Originally Posted by koputai

What I'm after though, is better performance at home, so I can get outside and have a look more often, not sit inside and wait for one night a month away from home.

Light pollution is pretty limiting, and seeing as you have an 8" scope I think you would be disappointed in the results of buying a bigger scope hoping to see a big difference under such conditions.

You're not the only one that hates light pollution believe you me!

Theres still the moon and the planets

Domol (Domenic) · #10 05-03-2008, 09:41 PM

Bigger scopes allow you to collect more light, so that narrow band filters can be used. For example i can see the Helix neb from melbourne with an OIII just as well as from dark skys without OIII. this applies to most nebulas and PLs. Galaxies, however are a write off from cities, but details on planets makes no difference where you are