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RainLaw

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RainLaw

RainLaw

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Despite so many forums I can't find any that already answer my questions.

Im in birmingham(2nd biggest uk city), when gazing from my garden, on a cloud free night I can see the bright starts plus a few dimmer stars, the black is infact black but when I do a 30sec exposure on my dslr the skie is a bright pink. I'm guessing thats the light pollution thats making me unable to see the rest of the stars ....

IMG_0997 | Flickr - Photo Sharing!

....but what i really want to know is how much i will be able to see when i buy a telescope where I live.

Is it a case of i can basicly view anything but it will be dimmer or am I limited to acertain brightness of object.

Is there any test I can do to give me a better idea of what I'l see before I make a purchase.

I want a scope to view deep space & was thinking of getting the 200p 8" skywatcher (should be buying in decmeber).

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John

John

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Hi RainLaw - welcome to the SGL forum !.

I'm not an imager but that sounds like light pollution to me. It might not be too bad for visual observing though if the skies look dark and you can see some stars visually. Objects like the moon, planets, binary stars, brighter star clusters and of course the Sun (only to be viewed with the appropriate equipment of course !) can still be enjoyed despite some light pollution. Having a scope will increase the range of what can be seen despite light pollution.

My tip would be to do lots of reading and ask lots of questions on here before you buy anything - there is a lot of choice and it can be quite confusing. Lots of folks here will happily guide you through the maze though :)

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onesmallstep

onesmallstep

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Hi and welcome to SGL

200P - the Newtonian or Dobsonian? The Dob might be the better purchase if you haven't used scopes before as is a simpler design and more starightforward to use. Also, you can get filters to deal with the light pollution.

The Birmingham / West Midlands area has several astronomy clubs and societies so approach one (or more) of them to get advice and info about the types of scopes, observing methods, etc. Type 'fedastro' into your search engine and click on the Member Societies link.

HTH.

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x6gas

x6gas

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It's not quite that simple, but it's not that complicated either when you wrap your head around it...

The two main things to look out for when buying a scope are the aperture and the f ratio. The aperture determines how much light your scope can grab and the f ratio (which is the ratio of aperture to focal length) determines the field of view (i.e. how much of the sky you can see).

Telescopes with low f ratios are known as 'fast' scopes. They gather light quickly and so on a photographic plate or ccd sensor exposure times can be reduced.

For small targets (like planets) you need high magnification which means a longer focal length and a higher f ratio.

For visual DSO you generally need as much aperture as possible to gather as much light from these faint fuzzies as possible. Some DSOs are also quite large so a scope with a low f ratio is good.

However, for astrophotography you can gather more light by leaving the shutter open for longer and so aperture is not quite so important.

For light pollution, your DSLR picture is a bit misleading. You won't see such polluted sky visually and the higher magnification of the view through the scope also means it will be much less noticeable in a 30 sec exposure....

Light pollution filters do a good job of screening out this glow anyway and in urban areas are a good investment.

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John

John

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.....200P - the Newtonian or Dobsonian?......

Theres that confusion I spoke of :)

A dobsonian scope is a newtonian scope, but it's on a simple mount designed by a guy called Dobson - hence dobsonian :)

With the Skywatcher 200's the one on the equatorial mount has a focal ratio of F/5 wheras the one on the dobsonian mount has a slower focal ratio of F/6. That might be too much detail at this stage though :)

Both designs have pros and cons depending on where your interests lie although both are excellent and highly recommended :)

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John

John

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I recommended the Dob as the Newt refers to setups with equatorial mounts which can be offputting for the newcomer.

Valid point though!

I know what you were getting at John, and it was a sound recommendation :)

It's funny how names stick with equipment sometimes isn't it ?

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crazyjedi

crazyjedi

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Hi

Where about in B'ham are you? I'm living in South B'ham and yes the light pollution is a bit of a problem. But...If you sit out in your garden on a clear night for more than half an hour you'll notice that as your eyes become accustomed to the dark more and more stars will spring into view. from my back garden i can get some reasonable views. Stars and planets are easy targets and easy to view. DSO's are a bit more of a challenge because the light pollution can wash them out. I can however see The Andromeda galaxy, the dumbell nebula, the great globular cluster in Hercules and the Orion nebula etc.. So even though I can't find the faiter DSO's with my light pollution and modest scope there's still lots to see :)

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onesmallstep

onesmallstep

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Hi jahmanson

I'm biased as I'm after the SW Skyliner 200p so promote that particular model. Also, I prefer the KISS approach (Keep It Simple and Straightforward) such as altaz mounts.

Agree with you on the name thing. I'd like to meet the telescope inventor called Cloud-Magnet!

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John

John

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Hi jahmanson

I'm biased as I'm after the SW Skyliner 200p so promote that particular model. Also, I prefer the KISS approach (Keep It Simple and Straightforward) such as altaz mounts.

Agree with you on the name thing. I'd like to meet the telescope inventor called Cloud-Magnet!

You and I think alike on all those things John - and share the same name to boot :)

I love alt-az mounts :)

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acey

acey

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....but what i really want to know is how much i will be able to see when i buy a telescope where I live.

Is it a case of i can basicly view anything but it will be dimmer or am I limited to acertain brightness of object.

Is there any test I can do to give me a better idea of what I'l see before I make a purchase.

I want a scope to view deep space & was thinking of getting the 200p 8" skywatcher (should be buying in decmeber).

For deep space (i.e. galaxies, nebulae and star clusters), as opposed to Moon and planets, the crucial thing, as you have already guessed is the darkness of the sky.

With a 6" telescope you can see at least 600 deep-sky-objects, and more likely more than a thousand, if the sky is dark enough.

With a 32" telescope you will see no deep sky objects, if the sky is too bright.

So the real question you're asking is: how dark is "dark". And the rule of thumb is that a genuinely dark sky for deep-sky viewing is one in which you can see the Milky Way with the naked eye. It sounds like you'll need to do some travelling to get a sky that dark, so you might want to think about that.

It is possible to see some deep-sky objects from a light-polluted site, especially clusters and emission nebulae. Some galaxies are visible, but in a bright sky you see only the central featureless cores rather than the fainter outlying details.

At a dark site I've seen the spiral arms of M51 with an 8" scope. From my back garden the same scope shows it as a faint blob. A bigger scope would show it as a bigger blob.

Planetary viewing is not affected by light pollution, clusters can still look pleasing, and emission nebulae can be seen with a filter (some are in any case inherently bright: e.g. the Ring or Eskimo nebulae).

An 8" dob is easily moveable and transportable and makes a great "all-rounder" for back garden or dark site use.

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RainLaw

RainLaw

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wow you guys respond fast, thank you for all the posts. the scope with the mount was what i had in mind, i figured I'd be able to do more with it in a sense that I'd be able to upgrade to a goto mount in the future if i stuck with it and also attaching my dslr.

Thx Rob for your viewing specifics, im also in the south (Bartley)

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crazyjedi

crazyjedi

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Birmingham Astro Society are having a viewing evening up the Lickey Hills on the 7th October so that may be worth a visit. Wouldn't call them dark skies but better than what I have here in Rednal/Longbridge.

Wow that's local for me. I'm in Rubery.

Can anyone (such as me) turn up and join in?

How would I find everyone? The lickey hills is a fairly wide area

Cheers

Rob

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Veracocha

Veracocha

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I'm in Ashill if you know it, opposite Morrisons/The cinema/Hollywood bowl/The Gym/Frankie & Bennys'/Travelodge (talk about light pollution). This is why I have had eight star parties this year alone. Anyone can turn up (I will), it's at the visitor centre at the top of Rose Hill.

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acey

acey

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acey me main prob is i have no transport so im pritty much stuck where i am. if you were to take pictures of M51 using ur scope as the lense would you be able to enhance the image with photoshop or wud it always be a faint blob

Can't comment as I only do visual, but from what I can gather, it's possible to get remarkably detailed images from light-polluted sites with small aperture - and considerable input of time and cash.

Objects like the Ring Nebula (M57) or Hercules cluster (M13) are great to look at, even from a light-polluted site, so as along as you don't expect too much from galaxies there's still useful deep-sky viewing to be done.

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