So just what IS the best scope for suburban astronomy?

[koputai (Jason)]

Folks,
Now we have Bambo's 597 to chase, I'm wondering a bit harder at what might be THE best scope for suburban visual astronomy. I'm interested in just the viewing result, not the portability or cost issues.
Is it a 24 inch f5 Dob? Is it an 8 inch f10 E.Q. Or is it even a 60mm f11 refractor?

Some questions:

Larger or smaller aperture?

Everyone always says 'Bigger is better' when it comes to aperture, but is this really true in light polluted suburban skies? Does extra aperture just collect more light pollution? Does a bigger aperture improve or degrade the signal to noise ratio? If bigger IS better, then is there a sweet spot, where going bigger evens out of possibly gets worse?

Faster or slower f number?

Faster gives a brighter image, but slower gives a darker sky background. For a given aperture, is faster or slower better?

Thoughts?

Cheers,
Jason.

[Barrykgerdes]

I have used an 80 mm refractor and many sizes up to 16" from my home location. In a light poluted area I can see the same things visually with the 80 mm and the 16". The improvement with the 16" over the 80mm is only marginal except for planetary viewing.

I now can use an ETX 125. From a dark location like Crago only 40 Km away it can see DS objects plainly that I can't see from home with a 16". I have now sold the 12" and my observatory and set myself up for easy portable operation. I also use a 10" LX200 as portable and I can set it up for Full operation in the field in as little as 5 minutes. The 16" is too heavy for me to use regularly so it only gets used on special occasions.

Barry

[mswhin63 (Malcolm)]

I must agree using a 12" in my area heavily light polluted is difficult to get all that it is possible for the 12", but my ulimate intention is to take the 12" with me in dark non polluted area so I intend to keep it. (making it more transportable)

If you only intention is the burbs then a 12" might be a bit overkill.

[Starkler (Geoff)]

Originally Posted by koputai

Everyone always says 'Bigger is better' when it comes to aperture, but is this really true in light polluted suburban skies?

It is ESPECIALLY true in light polluted areas.

Small scopes need dark skies to do anything useful at all with other than lunar/planetary obs.
A 12"er is a nice size, and if stuck with lp I probably wouldnt bother with anything bigger or smaller for that matter.

[tnott]

When the scope gets bigger then filters like UHC and OIII work much better. So with, say, a 16" scope you will be able to view many more emission nebulae than with a smaller scope. The OIII is especially good at blocking light pollution from my suburban skies with larger scopes, but it blocks too much light with apertures 8 inches and smaller to be really useful. Only works on certain objects too.

You will also get more resolution on planets etc. but only if seeing permits.

Images are also brighter so compensate somewhat for eyes that may be not as dark adapted as in country skies.

[Robh (Rob)]

Jason,

The real question is whether the object you're trying to look at is brighter than the surrounding skyglow. If not, you're not going to see it with any size telescope. According to the Bortle Dark-Sky Scale, if you were in a rural area you would be able to see stars to visual magnitude 16 with a 12" scope. In the city, a 12" inch scope would only see stars to visual magnitude 13 due to skyglow. However larger objects such as nebulae, clusters or galaxies, even if they have a visual magnitude brighter than 13 may not be seen if their overall surface brightness is much lower than the surrounding skyglow.

If the object is brighter than the skyglow, the bigger scope will be better at collecting its light.

Regards, Rob.

[bmitchell82 (Brendan)]

I live in suburban perth, and have looked though a 7" Mak, 12" Dob, 10"dob, 8" dob, 12" LX200 and a ETX 125, they are all much of the muchness in the city. The thing that annoyed me with filters is the hue they impose on any other colors entering. but in saying that, this is what i would suggest.

Skyglow kills stars there for you need a goto system to view anything (how can you star hop with no stars to base off of) apart from the major nebule, stars and globs.

if you can get something like a 12" with Argo navis or some form of digital setting circles that would be best as your setup time is minimized. further more carting a 12" is dooable (make a trolly to move it around!).

Get yourself cirtain bandwith filters. LPF or UHCF, OIII, and cirtain others to give yourself the best chance of seeing stuff. Further more a few high quality eps to boot, like it has been said previously the 12 will give you good maginification though only in good seeing so if money isn't a option and weight factor can be got around.

- 12" solid tube/flex dob
- Argo Navis - push to system
- 0III, LPF, Nebula Filter
- 32mm UWA, 20mm UWA, 10mm UWA, 2x 2" ED barlow and a 5x Power mate (for really zooming in on planets).

With that setup you can see a whole lot of stuff galaxies included (i can do it with a 10" on a EQ6 with ease).

[Robh (Rob)]

Originally Posted by bmitchell82

Skyglow kills stars there for you need a goto system to view anything (how can you star hop with no stars to base off of) apart from the major nebule, stars and globs.

if you can get something like a 12" with Argo navis or some form of digital setting circles that would be best as your setup time is minimized. further more carting a 12" is dooable (make a trolly to move it around!).

This is a good point. I did some viewing through my 12" at my brother's place in suburban Sydney. I do all my viewing by star hopping. It was just too difficult to find objects as the seeing-eye limiting magnitude was about 4. For example, Alphard was pretty much the only star I could see in Hydra, so tracking down the planetary nebula Ghost of Jupiter (Vmag 7) was next to impossible.

Regards, Rob.