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Does light pollution really make it that bad?


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I have had me 6SE for a few weeks now.

My viewing location is a balcony of a second floor flat in Surbiton (near London).

After overcoming the initial alignment issues, I can find targets farily easily (those that I can see).

However I am disappointed with the views.

I have an 8mm hyperion which when pointed at Saturn I find impossible to achieve sharp focus.

The view of M13 really is just a smudge. M3 even more so.

Nothing else M-wise is visible at all.

Is this what I should expect? Or is this down to the light pollution?

I have noticed that when I defocussed my eyepieces the circles appear concentric around the centre in both my 40mm 2" and 17mm 1.25", but not so in the 8mm hyperion.

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you have a very good scope (from other comments - have never used one myself) and it has a focal length of 1500mm. this means at 8mm your magnification is 187x. This should be usable on many nights but not all of them and when seeing is poor, you might only get 150x (sometimes even less) before the view goes mushy (other than with the moon which can usually take more mag). it might be worth getting a 10mm eyepiece to provide a little less mag when the conditions are not ideal?

other than moon, planets and double stars, many/most targets are badly affected by light pollution. therefore most Messiers will be either hardly visible or lacking in definition.

they will often appear just as vague smudges even in the best (darkest) conditions.

your scope has a decent but still quite small aperture and increasing this would help even in light pollution but the best thing would be to observe such targets from a darker site. you'd then see a world of difference. a light pollution filter might help a little but I don't really like using them if I can avoid it.

Edited by Moonshane
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Nominally, you would get a 78% increase in light grasp, which equates to about 0.6 magnitudes.

Speaking as a 6SE owner, I would suggest you give it a bit more time. 'Getting your eye in' comes with time and experience. If you have a DSLR, you could try plugging it into the e/p holder and viewing the result of a 10/15 second exposure on your laptop ... that is what I do the majority of the time, also because of LP.

I would have to agree that a balcony is not the best site to set up the scope, but I understand that if that is all you have, it is better than nothing.

As the scope is very transportable (for its size ... and the 8SE being bigger is less so) is it possible to get to a dark site? Maybe meet up somewhere with other astronomers, getting the double benefits of a dark sky and their knowledge?

Just my 2p ...

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As has been suggested, this is almost certainly a "seeing" problem and not related to light pollution. Seeing relates to the stability of the atmosphere. In your case thermal currents around you scope and balcony are likely to be significant even though you aren't aware of them. If you look at the moon as you up the power you will probably notice that it start to shimmer. Looking at something like saturn it will be fuzzy most of the time but every now and then it momentarily snaps into focus. Don't change your scope until you have had chance to try it out at a different location. In the mean time the best way of coping with poor seeing is to use lower powers of magnification. Unfortunately your light pollution will stop you from having good views of most faint DSOs

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Maybe meet up somewhere with other astronomers, getting the double benefits of a dark sky and their knowledge?

Just my 2p ...

Your more than welcome to come along to the Surrey observers sessions. Find us via the community link/social groups at the top of the page.

We meet most clear nights on Ranmore common (just outside Dorking).

If transport is a problem send us a post and we'll see what we can sort out.

Regards Steve

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you only need to take a trip to the countryside to see what a difference light pollution makes.

from my back garden which is near a rural village centre i get really quite good views but last night i stopped at the side of the road on the A37 between yeovil and dorchester, no light pollution at all and the views were stunning, i could even make out the milky way, the number of stars visible to the naked eye was staggering.

mind you that was nothing compared to the views i had in egypt a couple of years ago, we made an overnight trip from sharm to cairo and the stars were staggering, i had no idea so many were visible. there were so many i had real difficulty making out the common constellations.

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mind you that was nothing compared to the views i had in egypt a couple of years ago, we made an overnight trip from sharm to cairo and the stars were staggering, i had no idea so many were visible. there were so many i had real difficulty making out the common constellations.

I have had that happen to me, it is quite bizarre to have so many stars visible that the familiar constellations vanish into a sea of stars...

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Here are two practical (and cheap!) DIY suggestions for you to help combat light pollution.

1. Make yourself a light pollution / dew shield that is at least 12" long (double your aperture) and either flocked or painted flat black. This can be done inexpensively with plastic and velcro for less than $10. Cutting out stray light as it enters the tube will really improve the contrast of everything you see!

2. Get yourself a hooded sweater (or even a large dark bath towel) to put over your head and block out stray light from your eye and the eyepiece itself. (Think of the old-fashioned photographers who used to hide under the black cloth to take photos!) I made myself a vest with a dark "monk's hood" that extends over me and the EP - it works great.

These will help quite a bit, and cost almost nothing. That said, there is nothing like dark skies!

Dan

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Your more than welcome to come along to the Surrey observers sessions. Find us via the community link/social groups at the top of the page.

We meet most clear nights on Ranmore common (just outside Dorking).

If transport is a problem send us a post and we'll see what we can sort out.

Regards Steve

Many thanks for the kind offer. I really do want to attend something like this, I currently use a rather large track based vehicle for transport so getting there wouldn't be easy!

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Here are two practical (and cheap!)

2. Get yourself a hooded sweater (or even a large dark bath towel) to put over your head and block out stray light from your eye and the eyepiece itself. (Think of the old-fashioned photographers who used to hide under the black cloth to take photos!) I made myself a vest with a dark "monk's hood" that extends over me and the EP - it works great.

These will help quite a bit, and cost almost nothing. That said, there is nothing like dark skies!

Dan

Thanks Dan, I will this definitely give this a go.

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I live just outside of Taunton, quite a rural area really. On a couple of nights I have seen the Milky Way but that is only a couple of nights per year. When it is visible it really does make it clear how the light pollution from Taunton is affecting the visibility - I can't even remember what it is like inside a city.

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I do remember being on a boat in the South Pacific when I was not able to go on a night dive due to ear problems. The difference between a night sky in England and the night sky hundreds of miles from any source of light pollution is truly incredible.

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Hi Monkey Coral. I have just bought a 6SE to complement my ED80. I live in the middle of a town an am forced to observe within 10 yards of a big yellow sodium street lamp.

Despite this I can see most M objects that are above the horizon of neighbours' roofs.

What makes the difference for me is a long (18") home made foam dew-shield sprayed matt black on the inside.

I also find a UHC filter useful when looking at nebulas like M57- it really does cut out the yellow background.

Finally where I live goto is an absolute must!!

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Does light pollution impact your seeing? Yes ... in addition to the impact upon your telescope, your eye may never truly become dark adapted making the situation even worse. For local light, a hood over your head works nice but can be stuffy on warm nights. Portable light shields work too. For London's skyglow ... difficult to combat. As you magnify your image you increase contrast but you also dim the image ... some people think the trade-off favors viewing ... others differ. I think a light pollution filter is marginal for a 6 inch scope.

Viewing off a balcony does have its problems but you have to take what you can get. The thermal impact of balcony or rooftop viewing will make using eyepieces having focal lengths shorter than around 10 to 12 mm difficult.

Heading to the country side and darkness once in a while will be a super treat where your 6SE can really show its stuff. Meantime, keep viewing to keep proficient in your viewing skills.

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IMHO your primary problem is seeing.. but Light Pollution also needs dealing with.

Shielding all local light sources makes a huge difference and if nothing else makes life much more pleasent. When I started out I had a streetlight pouring light direclty into my back garden. I contacted my local council and got a shield put on the lamp for a small sum. The effect was that the garden was then very much darker and the neighbours thanked me as the light trespass into their bedroom windows pretty much vanished.

But seeing is the reason you can't see a planet image properly and this is also something you can do something about.

You have 3 sources of seeing degredation.

1. The atmoshpere itself.. this effect comes and goes. when it goes if everything else is zero then you will see an image 'snap' into perfect focus.

2. Local seeing.. if you are on a south facing balcony on a brick building the heat radiating off that structure will cause the air to boil off its surface like a furnace, seeing would be dire, truely awful. If you can find a location where you can stand the scope on grass and you have no buildings (heating/hot bricks) beneath your line of sight for as far as you can mange then you can get the chance of being atmosphere limited.

3. The scope itself. The mirror/lense will not be the same temperature as the surrounding air. I was reading through the 'dream telescope' site the other day and they were talking about the effect of heating on a mirror being 0.3 to 0.5 arc seconds worsening in seeing per degree of difference between mirror and air... so forced air cooling of the mirror is important, even at this time of year as the air is cooling at night the mirror needs to keep up.

good luck and I hope this is of some use.

Derek

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I would say that the light pollution and the general heat from where you are and London in general will be your problem.

For the scenario you describe I would say that the 6SE is probably an ideal scope, keep the magnification down.

None of the galaxies show detail, there are all fuzzy grey blobs. I have seen Andromeda through a 14 inch and it is still a grey fuzzy blob. So you may have to reign in expectations.

Dark skies make a lot of difference, if really dark you will see more with just eyes then with a scope at an average place. Actually there can be too much to see. Casseiopia disappears in the milky way, literally unable to find Casseiopia.

Where you are will have a general heat haze, London is 3-4 degrees hotter then the surrounding area and that heat rises at night causing unstable, moving air for several miles.

I would certainly stick with the 6SE, nice size, nice scope. Find options to reduce the problems, hoods for both scope and you sound a good start. Perhaps a light polution filter, could someone lend you one to try? Saves buying to find it is useless.

Although not always possible but pick targets that are quite high, sounds basic but amazingly simple, and easily ignored. Depends if you can view high objects easily and if there is any thing up there to view.

Whatever you try post back the results, they may be helpful to other people.

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Keep trying - on some nights the local light pollution is much reduced. I also observe from a city, and some nights I only see down to Mag 2 stars, but on other nights I can glimpse Mag 4 stars near the zenith. On a good night the views of DSOs are vastly improved.

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I recently bought the Philips Dark Sky map and it really hit home the amount of light pollution out there.

I do have a reasonably dark back garden which is nice. Because I own a very transportable scope I am considering taking it to either Galloway or Kielder dark sky sites (which are both about a 2 1/2 hour drive from my house.

Book a b & b and spend a few days up there. The downside to that however is the weather is never guaranteed and it would be just my luck that I get everything set up, drive up there and the clouds roll in.

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The downside to that however is the weather is never guaranteed and it would be just my luck that I get everything set up, drive up there and the clouds roll in.

The wonderful world of amateur astronomy when living in a temperate climate eh? Have lost count of the number of events I have planned to observe only to be thwarted by clouds. We must all be bloomin' mad :)

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I would say that the light pollution and the general heat from where you are and London in general will be your problem.

For the scenario you describe I would say that the 6SE is probably an ideal scope, keep the magnification down.

None of the galaxies show detail, there are all fuzzy grey blobs. I have seen Andromeda through a 14 inch and it is still a grey fuzzy blob. So you may have to reign in expectations.

Dark skies make a lot of difference, if really dark you will see more with just eyes then with a scope at an average place. Actually there can be too much to see. Casseiopia disappears in the milky way, literally unable to find Casseiopia.

Where you are will have a general heat haze, London is 3-4 degrees hotter then the surrounding area and that heat rises at night causing unstable, moving air for several miles.

I would certainly stick with the 6SE, nice size, nice scope. Find options to reduce the problems, hoods for both scope and you sound a good start. Perhaps a light polution filter, could someone lend you one to try? Saves buying to find it is useless.

Although not always possible but pick targets that are quite high, sounds basic but amazingly simple, and easily ignored. Depends if you can view high objects easily and if there is any thing up there to view.

Whatever you try post back the results, they may be helpful to other people.

I have got an astrozap dew shield but I have only used it twice as it impacts on the location I can site my scope upon the balcony. I am sure it is not 18" long - off the top of my head I would say it was 12". is that not long enough?

This is my second scope and I had a reasonably realistic idea of what I might see. I have to say I have been disappointed that I haven't been able to make out the objects at all.

Your experience of Andromeda through a 14" is interesting though. In my ignorance I would have thought that you would start to see some detail on a scope that size. Which leads to the question, 'How big an aperture do you need to start to see some detail?'

Edited by monkey_coral
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The wonderful world of amateur astronomy when living in a temperate climate eh? Have lost count of the number of events I have planned to observe only to be thwarted by clouds. We must all be bloomin' mad :)

Oh, I don't know - that could be one of the hobby's biggest advantages . You can say to people "yes, I'm an amateur astronomer" when in reality you never actually have to partake. Since most of the time it will be cloudy and the rest of the time the Moon will be too bright, or during the summer the sky never gets dark enough -- or something else will thwart your efforts.

While people might call your bluff if you claimed to be a keen sailor and you lived up a mountain, almost nobody is aware that England (or other parts of the British Isles) is just as impractical from an astronomical point of view. Until that is, they've just shelled out £££s themselves on their first telescope :(

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