8" Dob effects from light pollution?

[Matt01]

Hello SGL,

For a while now I have been stargazing with a pair of SWAROVSKI EL 42 Binoculars. 

Since purchasing a copy of "Turn left at Orion" I am keen to buy a telescope and have identified an 8" Dob as a good place to start.

(either a Sky-Watcher SKYLINER-200P or a Bresser Messier 8" Dobsonian)

I've been reading posts for a while but seem to still be confused about one thing.

A number of posts warned against an 8" Dob if you suffer from 'bad' light pollution. None of them, however, defined what 'bad' light pollution is...

I live in a rural/suburb area to the west of hull. www.lightpollutionmap.info reveals that my back garden has a value of 2.89... (I don't know what unit this is)

however a there is a spot 13 minutes drive away with a value of 0.38.

Will this be too much?

(To clarify I am hoping to observe DSO's) 

Many thanks in advance

Matt

 

Edited July 23, 2020 by Matt01
clarification

[Guest]

I have the Sky-Watcher Skyliner 200P and live in quite a light polluted area (Bortle 6, sky quality 19.41).  Those figures are according to the Clear Outside app on my smartphone, based on the area I live in (post code).

I've seen planets from my back garden, the moon, double stars, etc.  I've even seen Messier 3, so it can't be that bad!

Edited July 23, 2020 by Guest

[fwm891]

@Matt01

Hi Matt, Welcome to the fold.

From your homme you will need some type of LP (light polution filter) to remove/reduce the effects of street lighting so that will reduce the amount of light getting into your eye, at your remote location you will be able to (possibly) get rid of the LP filter for many objects.

I expect as its your first scope (and a dob is a great place to start), you'll want to buy new but take a look at some secondhand 10 inch dobs the extra light grasp will help in both locations. 10 inch dobs come up for sale on the forum quite often and the UK Astro Buy & Sell site has many more.

Provided the extra physical size doesn't cause transport problems you'll get much more enjoyment from the hobby.

Good luck

[davhei]

I second going for 10” as a first scope, if you think you can manage the heavier lifting. In my view it hits a sweet spot balancing portability and light grasp. 12” would be a bit too unwieldy for me and 8” would present a similar threshold in lugging it into and out of a car for instance, but with slightly less aperture.

Wouldn’t be deterred by light pollution but if mainly dso’s are your thing I would certainly go to your darker site for observing as often as possible and save the home location for moon, planets and maybe double stars and bright clusters.

I also spent a year stargazing with swaro el 42’s. Finest binos I have looked through and wonderful on the night sky. I really enjoy the flat field and pinpoint stars but also the steady view and large FOV of 8.5x42 binos compared to larger ”astro binos”. Observed 30-odd messier objects with them from a reasonably dark site, bortle 4 or there about. Great way to familiarize yourself with the sky before jumping at a scope.

As you might have guessed I had first decided on an 8” but got talked into a 10” by a more experienced gazer at the local club. Haven’t regretted it.

 

Welcome to the lounge!

 

 

Edited July 23, 2020 by davhei

[John]

If you suffer from light pollution I would go for a scope which can be transported easily to a darker sky.

A 6 inch scope under a dark sky will out perform a 10 inch scope under a light polluted sky.

 

[davhei]

As long as you can comfortably lift it, throwing a 6” or a 10” into the car is a similar exercise and set up is also more or less the same, bar a bit more collimating with the larger one perhaps. Granted I’m saying that from the perspective of having an estate car.

Would definitely recommend more aperture to increase the chance of long term enjoyment, unless storage space is at a premium and the weight is an issue.

Choices, choices...

[Louis D]

You should be able to observe most solar system objects, open clusters, globular clusters, planetary nebula, and a few bright emission nebula and galaxy cores from your location.  Most galaxies, faint nebula, and comets tend to be a no-go from suburban skies (Bortle 5-6) because they tend to be faint and diffuse, blending in to the background sky glow.  Aggressive nebula filters such UHC and OIII can help with nebula, so there is hope on that front.

[Second Time Around]

I'd also recommend a 10 inch for its extra light gathering.  However a 10 inch is heavier and bulkier than a 8 inch.  I have both 8 and 10 inch, but they're OOUK Dobsonians that are lighter than mass market scopes.  Like the Bresser they have large altitude rings so are very smooth, plus it makes them easy to pick up and carry.  This is made even easier by the base having a smaller footprint so it can be carried close to one's body.  The base is made of aluminium so won't swell if it gets wet.  Even though I'm somewhat disabled, I can carry the 10 inch out in 2 trips.  An able-bodied person should easily be able to carry the tube in one hand and the mount in the other.

As you can see from their website (https://www.orionoptics.co.uk/VX/vx10-10l.html) they're much more expensive than mass market Dobsonians.  Unfortunately the 10 inch models rarely come up on the used market - I had to wait over a year for mine.

However there was an ad posted here by long time member Alan White, who had a 10 inch OOUK Dob for sale.  A lot of us commented that we were surprised it hadn't sold, but Covid was in full swing then.  It might be worth asking Alan if it's still available.   

 

  

[Alan White]

Not for sale anymore, I withdrew it.
I realised just how good it was and how much I was giving up.
There clearly was a reason it didn't sell, it was the Universe teaching me a valuable lesson.

I can however wholly recommend a 8 or 10" sized dobson design, very practical,
moved fairly easily by many and a decent sized light bucket.
Once you see M13 in one of these, your hooked.

[Second Time Around]

Just goes to show why they're so hard to find!

[Timebandit]

 

Hello. Light pollution can be very adverse on the fainter DSO.

Just to give an example. I have a 14" OOuk and a 8" OOuk. And the 8" at a Dark site will easily out perform my 14" at a light polluted site on fainter DSO

The 8" reflector is such a versatile scope and will perform excellent at true Dark sites. Aperture is only king on fainter DSO ,if you have the sky conditions to use it . True Dark Sky's are an absolute must for faint fuzzy hunting. And it is certainty worth the efforts to travel to a Dark Site. 

 

 

[Woj2007]

12 hours ago, Matt01 said:

Since purchasing a copy of "Turn left at Orion" I am keen to buy a telescope and have identified an 8" Dob as a good place to start.

If you think of 8", treat yourself with 10" and you won't regret. Always get a larger aperture than you think you need . The urban sky is often unjustly demonized when it comes to DS, but it is forgiving when it comes to details on the Moon and planets, even in poor seeing. Poor seeing doesn't cover optics  or aperture disadvantages. Even in poor seeing there are moments when higher resolution can show more. So,  good optics and large aperture is always better than mediocre optics and small aperture. 

I am living under an urban sky, Bortle around 7, and I was always desperate to get 8" as the maximum. My capable local astro seller convinced me to get 10" and he couldn't be more right.

I have now a 12" for dark sites, but the 10" (250/1200mm) remains my main urban all-rounder. 

[Chefgage]

I have the 8" version and live in a bortle 8 sky (Scunthorpe so not far from you). I have seen quite a few of the messier 110 list. Ok so a lot of them are just faint smudges which is to be expected but never the less I still found them from my heavy light polluted garden. I have seen M57 the ring nebular which I was very happy that I found it. The 8" version is quite easy to move around/put in the car etc.. But I cannot comment on the 10" version as I have never seen one. 

I am actually thinking of selling my 200p which has been modified with digital encoders, lazy Susan bearing etc..  it's this one

 

Edited July 24, 2020 by Chefgage

[Matt01]

Thanks to everyone for their helpful replies,

10" seems like the best bet then. Whilst I was thinking over buying new, I will definitely be snooping the classifieds for any good deals... seems like I just missed the boat on a 10" Bresser but I'm sure something will become available. 

The majority of my stargazing is at dark(er) sites, however I have a land rover discovery which means that space isn't an issue at all... (practically a van) I also have no issues with lifting larger objects... 

I am also considering paying a visit to rother valley optics (when they open), to see 10" Dobs in person. its hard to get a sense of scale from the pictures. You also can't get a 'feel' for the quality.

[dozmodo]

I have a 10 inch dob and live next to a strip mall and mini storage. Light pollution is terrible. But I can find the planets and quite a few DSO in my scope. 

It's when I want to take pictures that I run into issues usually.  Thats a whole other topic...LOL

Enjoy the scope when you get it.  Get a carry case. My 10 inch has one, it makes it so much easier to transport it. I can throw it over my shoulder and carry the mount that way. 

 

[Cosmic Geoff]

On 23/07/2020 at 11:00, Matt01 said:

A number of posts warned against an 8" Dob if you suffer from 'bad' light pollution.

Possibly the point being made here is that if the sky is dark and ablaze with stars it makes it a lot easier to find objects with a manual telescope (e.g. a Dobsonian), by star-hopping.

With a GoTo, the finding system is unaffected by light pollution so long as a few bright stars are visible and can be used for a star alignment.  Whether you will see any dim objects when you look through the eyepiece is another matter, just as with a Dobsonian mounted scope.

You will see many, many more galaxies from a dark skies site than from a town.

[PaulM]

I live under bortle 6 skies and could see a lot with my old 200p and spent hours observing dozens of targets a night so definetely get one as said if your budget allows go larger I have a 14" flexi which is manageable