Does aperture ever beat a dark sky?

[UHF]

I'm still fairly new to this but having only observed from a light polluted back garden with a SW 200 Newt, I have yet to see the impact a good dark sky can make, so I'm off to Galoway Forest in March for a long weekend.

I'm pretty sure I'll be blown away with an 8" scope in one of the best dark sky sites in the UK, so I was wondering, at what point does aperture become more desirable than a dark sky.

eg. a 16" Newt in LP skies vs a 5" Newt in a dark sky.

The reason I ask is that I need to make a decision, either buy a massive scope which stays at home or stick with my 200 which is on the borders of portability and go outside of town, that said the local dark skies wont be the same as Galoway!

I suspect that the answer is that aperture will win eventually, but at some ridiculous size with seriously heavy LP filters.

Transport and size aside, I quite like to observe from the garden as it doesnt take much time and I can pop inside to warm up every now and again, make fresh drinks etc etc.

I see a few people do very well from LP skies when doing AP, I'm guessing there that exposure time and processing deals with the LP better than the fixed capabilities of the human eye which is maybe an option but there isn't quite like having ancient photons entering your own eyes.

[rory]

all the info ive read , and from stoies told on the forums here, the answer is no.

dark sky is the way to go.

i would imagine views in your 8" from even a moderately dark sky would take your breath away .

im guessing, but if you asked the guys on here who have had lots of experience, and you offer them 8" in dark locations or 16" in a red zone. i dont think many will tick the 16".

[todd8137]

my lp is real low mainly from next doors kitchen light but even if i did have lp i would still have a 16",light pol should not put you off

[kniclander]

aperture will win in theory in terms of resolving detail on planets etc and will also allow you to use filters for certain objects in LP'd skies. generally, I have found that for faint stuff, no amount of aperture makes up for light pollution, ie you see more faint stuff in a 3" scope under dark skies than a 10" scope in suburban skies.

[philj]

To use a saying from my old physics lecturer, "the wider you open the window the more muck flies in" He used to say that about hifi but teh same can be true of apeture.

If you are in a light polluted area a 16" will pull in the LP as well as the faint stuff thus you will still suffer from contrast problems. So yes it will help a bit but it wont get rid of the problem.

There is no substitute for a dark sky, Galloway will spoil you:)

Philj

[UHF]

I guess your teacher was talking about signal to noise ratio, so more aperture means more noise too. hence my comment about using lp filters, I need to find someone with a 16" dob I think and see for myself

Sent from a planet somewhere in the vicinity of betelgeuse.

[Merlin66]

Big scope, dark skies - an ideal location!

[Macavity]

Perhaps one should retain a vestige of optimism, even in light-polluted areas? After "suffering" for many years, my current skies are "mag 5" (sometimes). With a Video Cam, I can "see" galaxies (surface brightness 12-13?) - Stars at mag 15+ too? The "sky background" is theoretically "mag 18"? But I sense electronic chip noise comes in before that. VISUAL astronomy may often be a "dead loss", but maybe you can extract something... Electronically?

You can tweak the contrast, gamma settings etc. too.

The above may be rubbish speculation thoughbut!

[swamp thing]

I need to find someone with a 16" dob I think and see for myself

Where abouts are you? You're more than welcome to try mine.

I'm afraid the other comments hold true, a 16" under a city sky cannot show what a 6" can from a good dark one.

This is why I never bother observing from home.

Regards Steve

[dph1nm]

In term of signal-to-noise the answer is aperture will eventually win, but ...

Suppose your sky is 5 mag brighter than a dark site (e.g. 17 mag/arcsec**2 rather than 22 mag/arsec**2). Then this means you are getting 100x more counts from the sky. So imagine a scope which collected 500 photons from an object and 10,000 from sky at your light polluted site. This is a s/n~5 (500/sqrt(10000)). From the dark site the same scope will give a s/n of 50 (500/sqrt(100)). To get this s/n at the light polluted site you will 100x the number of photons i.e. 50,000 from the object and 1,000,000 - so your telescope will need to be sqrt(100) i.e. 10x the aperture (or you could exposure for 100x as long!). This rapidly gets impractical for amateur scopes!

LP filters may help a little - but remember they cut down the signal from the object as well as the sky so it is not always clear how much advantage you will get.

NigelM

[RikM]

In real life, you can't beat a dark sky.

[Northern Soul man]

Hi ya UHF, I observe from a very light polluted sky here in the West Midlands, the plus points - Constellations are easy to learn (only the bright stars visible) there's a great amount of star clusters, globulars and open which shine through the LP - Planets - easy - the Moon (wow) and the majority of the Messiers - nice and bright - the minus points - the very faint Galaxies, clusters and planetaries - visually bland and grey so, observing from your back garden wont be as bad as you think, I love the hobby - as do the majority on here - just going out and setting up ready for a session wondering what the seeing conditions will be like -you can see by my Avatar that I've owned a few scopes - small and large, but I'm in the process of upgrading to a Celestron cpc 1100 (gotta wait 2 months as no stock in the UK) so in the meantime I'll be using a 127 Mak (the only scope I have left) to observe with - Yes filters do help a little, but I find once I've put the filter in I'll then swap eps to see if the object can be seen without the filter. You have to look at the complete picture - Yes a dark site would be fantastic, but most of your observing will be done at home, its great just to get out and observe - theres always something visible wether its a telescopic object or fine in binos and if like me you'll learn to live with LP - I'm afraid its here to stay - unless the local councils want to save money and switch off all the lights (lets hope) I've gone from using a 12" dob - down to a 127 Mak for a couple of months and I'll still be out observing Mars just knowing that tinkering with a few filters will enhance whats there and loving every minute of it - don't be put off by a few faint fuzzies - that really need a very large scope to see visually and just get out and observe - there's my bit sorry for a long reply - but I really love and enjoy this strange hobby and have learned to live with the limitations of a suburban sky - there's a hell of a lot still to see, so, next clear night I'll be out again - as will the majority on here - Wonder if your a Radio Ham by your username - me too regards and clear skies. Paul.

[hemihaggis]

so where in galloway you heading for .......????

[rory]

Hi ya UHF, I observe from a very light polluted sky here in the West Midlands, the plus points - Constellations are easy to learn (only the bright stars visible) there's a great amount of star clusters, globulars and open which shine through the LP - Planets - easy - the Moon (wow) and the majority of the Messiers - nice and bright - the minus points - the very faint Galaxies, clusters and planetaries - visually bland and grey so, observing from your back garden wont be as bad as you think, I love the hobby - as do the majority on here - just going out and setting up ready for a session wondering what the seeing conditions will be like -you can see by my Avatar that I've owned a few scopes - small and large, but I'm in the process of upgrading to a Celestron cpc 1100 (gotta wait 2 months as no stock in the UK) so in the meantime I'll be using a 127 Mak (the only scope I have left) to observe with - Yes filters do help a little, but I find once I've put the filter in I'll then swap eps to see if the object can be seen without the filter. You have to look at the complete picture - Yes a dark site would be fantastic, but most of your observing will be done at home, its great just to get out and observe - theres always something visible wether its a telescopic object or fine in binos and if like me you'll learn to live with LP - I'm afraid its here to stay - unless the local councils want to save money and switch off all the lights (lets hope) I've gone from using a 12" dob - down to a 127 Mak for a couple of months and I'll still be out observing Mars just knowing that tinkering with a few filters will enhance whats there and loving every minute of it - don't be put off by a few faint fuzzies - that really need a very large scope to see visually and just get out and observe - there's my bit sorry for a long reply - but I really love and enjoy this strange hobby and have learned to live with the limitations of a suburban sky - there's a hell of a lot still to see, so, next clear night I'll be out again - as will the majority on here - Wonder if your a Radio Ham by your username - me too regards and clear skies. Paul.

:icon_salut::icon_salut:

well put sir...

[Merlin66]

NSM,

If you break your message into paragraphs - it would make it MUCH easier to read- sorry.

[Caldwell 14]

NSM,

If you break your message into paragraphs - it would make it MUCH easier to read- sorry.

Pedant.

[stevetynant]

the beauty of a really dark sky site like you'll get in Galloway - is you probably don't need your scope the first time its just awe inspiring with the naked eye.

[Ags]

Back to the topic :-)

I have just come back from Nepal where I observed with an 80mm scope at 2000m and perfect dark skies. It was like the astronomy godmother turned my ST80 into a 10 inch dob for the night! Objects I can never see at home, like M78 and the Flame, were easy spots under dark skies. The clusters I could barely make out as home were bright, rich and well-defined under dark skies.

[Caldwell 14]

I live in Humberside, a couple miles from the bridge. I work for a college and deliver work based qualifications in social care and get about a fair it. I have just been given some students miles away in Matlock, fantasic! I get to stay over night in the peaks, I'm orignially from the Cheshire peaks so can visit family 30 minutes away and turn my TAL into a serious bit of kit, great stuff.

[Northern Soul man]

blumming Hell guys

Some of you

Don't half

Get around

The UK

And abroad

Can only wonder

At the skies

Your under

Sorry Merlin

Couldn't resist

Nice thread

Regards and clear skies

Paul.

[Stevie816]

HI UHF

Dark Skies win every time. I occasionally go to Scotland and the views from the hills there are really inspiring. I mean awesome in the true sense. I agree with the others the view itself is enough without a telescope. Make the best of where you live but plan a small adventure to a dark site.

It will change your ideas about astronomy for ever.

[Moonshane]

I am going go slightly against the general trend here. I have a 16" dob and previously had a 12". I also have two 6" scopes - one a f11 for planets and the other an f5 for wider fields and grab / go.

I live in a quite bad area for light pollution, about three miles from Stockport and about 9 miles from Manchester. I live in a well populated area too so local window lights etc are a big issue.

I have observed from dark sites and there is no doubt that this makes a HUGE difference to the fainter targets but also the brighter targets like the brighter clusters (e.g. double cluster). Unfortunately, I can rarely get to dark sites due to work / family / cannot be bothered commitments and setting up in the garden is so easy and quick compared to this.

Sure I'd sooner be at a dark site with my big dob every weekend but this will never happen.

My point is (at last you cheer) that despite what many say, there is no doubt, at least to my mind, and based on my own experience here, that aperture also enhances virtually everything you see at home despite the light pollution. Therefore if you feel you will gain the benefits of more aperture and can handle the weight and size etc then don't let a light polluted back garden be the reason not to get it.

As a basic example, I was recently looking at the Orion Nebula with the 16" dob and (both filtered with a UHC and unfiltered) the view was truly spectacular. With more aperture, it's just amazing what you see even if conditions are not perfect. Personally, I will always prefer my big dob to the others no matter where I am, unless there's a likelihood of rain etc.

[Northern Soul man]

Nice 1 Moonshane, my thought exactly, seems that a lot of people forget that Stargazing means getting out and doing exactly that "stargazing" wether they have a little"dirt" on the mirrors - the lens has a little "dust" on it. Forget all that and just observe with whatever scope/binos you have and enjoy the night sky.

I've only got my 5" for a while now (ooherr!!!) and intend to get out and observe as much as I can - yes I know Mars is not at its best this apparition about 13 Arcsecs now, but still find it fascinating to align and sit there just looking - swapping eps and filters to get the best out of the scope.

People with larger scopes than this find they have "poor" views of Mars, but the challenge is making the most of what you have and not to worry about "dirty" mirrors or "dusty" correctors, set up and away you go.

Of course I can't wait for the cpc 1100 to arrive, but by the time it does Mars will be well past its best and the lighter nights will be on the way - but Hey - there's always Saturn to look forward to and - yes - a 2 year wait for Mars - but just look at the amount of observing I'll be doing til then - Nice 1 Moonshane - My thought exactly.

Paul

[UHF]

Thanks for everyones replies, nice to get some scientific responses as well as some feelings from peoples experiences.

I'm not a radio ham, name is a long story. I'm staying here Arnimean | Self Catering Holiday Cottage | Galloway Forest Park Dark Skies | Barrhill | Girvan | South Ayrshire, looks like a new place just opened, so far the people have been very accomodating and even offered to allow me to order shopping the day before so they could load the fridge freezer up for us

Looks like a very good location, obviously I'll be taking my 8" Newt.

Reason I ask is that I don't see myself spending much time travelling away from home so being able to observe from my back garden will give me more time to observe, atleast in the early days of the hobby I think time at the scope and generally looking up is probably more important than one amazing view for 5mins in a cold field. I tend to stay out for several hours at home (or have done so far).

I guess I'll know more when I've visited a dark sky site and seen for myself but given my location just 20 miles out of London, I doubt anything even within a few hours will rival Galloway so its not like there is an amazing site just 10mins away.

AP isn't for me as I think I said as I can look at other peoples pretty pictures online, I'm more blown away from the challenge of learning the sky and star hopping, photography is not for me as it feels like a different discipline entirely.

If I do go up in size, I'm now thinking that it'll have to be a Dob as things stay "relatively" cheap compared to larger Equatorial Newts.

For now I'll keep observing with what I have, just won a Telrad on Ebay so I can take my star hopping to the next level.

BTW, does anyone else take thier finder scope out sometimes when they dont have time to setup a mount and scope, guess I need some bins.

BTW also, paragraphs help, triple line spacing does not

[UHF]

Just found this

http://www.hertsdirect.org/docs/pdf/h/hccimpmap.pdf

Street lights in my area being converted spring 2012, so basically any month now

More aperture and better skies for next winter for me then