Dob scope for light polluted yard

[ericleo1]

Im still wondering if the Heritage 130p Dob with open tube woud let in too much surrounding light. Is the Starblast series still on the market? Is there a closed tube Dob as good as the Heritage does anyone know? My budget is under £200

[billyharris72]

Hi there. The open tube design might be an issue if there is a source if incident lighting nearby, like an awkwardly placed streetlight that is basically shining onto your mirror. If it's just a case of more "ambient" light pollution and washed out skies then it won't make any difference at all.

In either case though, the Heritage 130 will do the business - it's easy enough to make a shroud to cover the open part of the tube (I used some black flexible foam sheeting from Hobbycraft, but anything opaque with a matt black finish will be fine. I think for the money there isn't a better scope out there.

If you really want a closed tube, Bresser does a 5 inch Newt on a Dob base that looks pretty good, but is about £180, so a bit pricier. As to whether it's as good as the Heritage, I'd be surprised if it wasn't very similar indeed - 5 inch mirrors are not that hard to make and performance is unlikely to vary much.

Billy.

[Prador]

If you're concerned about stray light then a closed tube design would be better. The Skyliner 150P Dob would offer a lot of aperture (6") for very slightly over your budget (£209).

I believe the Starblast range, if you mean the Orion scopes, still sell on Amazon but the 150P would provide over 70% more light gathering ability. Probably worth the extra spend.

[billyharris72]

4 minutes ago, Prador said:

The Skyliner 150P Dob would offer a lot of aperture (6") for very slightly over your budget (£209).

Indeed - this would be even better if the budget could stretch. Somewhat brighter and better image is one thing, but the other thing to bear in mind is that it can sit directly on the ground (the 5 inchers tend to need a table, which is invariable awkward and less stable). You will sacrifice a bit of portability, but the 150P is not a heavy setup and is easily transported by car. As a backyard scope it would be a great choice.

[RolandKol]

42 minutes ago, ericleo1 said:

Im still wondering if the Heritage 130p Dob with open tube woud let in too much surrounding light. Is the Starblast series still on the market? Is there a closed tube Dob as good as the Heritage does anyone know? My budget is under £200

I had SW250 Flexitube and was not able to see Andromeda from my backgarden in Woolwich, London...

I tried to hide in the shadows, even used garden umbrella... - no luck...

So extra shielding will help you a bit... I would be more concerned about 130mm.... in the light polluted area it may be an obstacle..

[ericleo1]

Thanks Roland - Do you mean 130mm wd be too big and I wd be better with smaller apperture? (I mainly want to split double stars and see Messier objects.)

[ericleo1]

Thanks to all who replied - How about the Skywatcher 100p Dob - are the optics ok do you think? I amy go for smaller scope as it is for occasional use only and there are street lights nearby! Maybe a refractor wd be better for star-splitting?

[pregulla]

With smaller solid tube you will see less than larger open tube. I have 8" collapsible scope. Adding a shroud and dew/stray-light shield doesn't make too much of a difference. Maybe you can shop for larger used dob to fit your budget.

[RolandKol]

8 minutes ago, ericleo1 said:

Thanks Roland - Do you mean 130mm wd be too big and I wd be better with smaller apperture? (I mainly want to split double stars and see Messier objects.)

Opposite. 
I am not 100% sure about the minimal requirements to split the double stars, - but the larger one will be an advantage by all means.

Plus... pleas check what F number you need for this task... I doubt F5 will do the job... You probably need something around F10.
 

[RolandKol]

P.S.

 

https://www.cloudynights.com/topic/366092-minimum-separation-to-split-given-magnification/

 

 

 

[billyharris72]

1 hour ago, RolandKol said:

Plus... pleas check what F number you need for this task... I doubt F5 will do the job... You probably need something around F10.

Focal ratio will be relevant if you go down the frac route (and don't want spend a fortune) due to chromatic aberration. It won't matter much for a Newt. On axis an f5 Newt is pretty much as sharp as at f8 or f10 (collimation becomes more critical, but is still easy with smaller mirrors; one definite advantage of the Heritage is that you can look into the focuser while collimating, which makes things incredibly fast and easy). This would also be a another plus for the Skywatcher 150P Dob, as that's f8, and at that ratio collimation is not fussy at all.

A really good refractor will beat either of the above scopes on double stars, but nothing within a £200 budget will match either.

Billy.

 

 

[Carbon Brush]

Any scope at the sort or money you are looking to spend will benefit from low cost DIY modificationa.

For example, the black paint inside a tube is often not that black. Flocking will help.
Focus tubes and associated parts are sometimes shiny.
Using a dew shield to extend tube length will help with stray light.

The biggest help to your budget is of course to buy used.
scopes advertised on this forum tend to well looked after.
With ebay, you are taking a big risk.

Take your time before jumping in to buy and keep asking the questions.

David.