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 Post subject: M57 and Expectations
PostPosted: Sat Jul 30, 2005 5:13 pm 
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Joined: Fri Dec 03, 2004 12:51 pm
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Location: Stoke-on-Trent
The Northern Binocular Highlight, on page 52 of August's Sky & Telescope magazine, is an interesting read. It talks about viewing the Ring Nebula in Lyra, and the fact that it should fall easily within the range of a 50mm binocular! I'm assuming it means from a suitably dark sky location. The argument is that observers are quite often biased by their last telescopic view of the object, or by a colour photograph in a magazine, and miss the object in a binocular. Gary Seronik describes it as a faint, slightly out of focus star. I've never managed to see it using a 50mm binocular (perhaps for this reason), even from a dark sky site. I wondered if anyone else has ever had any success?

Jeff.


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PostPosted: Sat Jul 30, 2005 5:54 pm 
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Joined: Sat Dec 04, 2004 9:26 am
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Location: Norton, North Yorkshire
Hi Jeff

I recalled seeing M57 from my backgarden and have found reference to it in my observing record book.

All I have written is 'Saw with binos even though street light close by', if I remember rightly, it looked like a fuzzy star.

The date was 16 May 2004 and the time between 22:30 and 23:15 BST. I did do some observing with my 8" reflector after that. In fact that was the evening I made the sketch of comet Macholz ( C/2001 Q4) and it was on the front of one of the SPA news circulars.

The binos would have been 50mm and I wouldn't class my back garden as a particularly dark sight!

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PostPosted: Sat Jul 30, 2005 6:07 pm 
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Location: Stoke-on-Trent
Thanks Mell, that's encouraging to know, I shall give it another go on my next observing session.

Coincidentally, I was looking through some past copies of the SPA News Circulars last week and came across your drawing in the August 2004 News Circular - it's an excellent sketch.

Jeff.


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PostPosted: Sat Jul 30, 2005 7:26 pm 
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Location: South Lincolnshire
I'm pretty sure that I've managed to see M57 with a 10x50 binocular. During an observing session on the 12th of July this year I was having a look at the general area of M57 with the bin' before turning the 'scope on it and noticed what you descibe (an out-of-focus star) in the correct location for M57. I made a mental note (but not a written note for some odd reason) to check if I should be able to see it with 10x50s but then forgot all about it. Your post has now reminded me and would seem to confirm that I had indeed seen it.

While I do live in a reasonably rural area my own garden isn't a good dark-sky site by any measure. I've got a street-light that shines into the garden and also a pub next-door which has some external lights (although, looking in my log at the time of when I observed M57 the external lights will have been turned off). There's also a haulage yard some distance away which has a single, bright "security" light that throws some light my way too.

So, as with Mell's experience, I would guess that you don't need the darkest of skies to stand a chance of seeing it.

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 Post subject:
PostPosted: Sat Jul 30, 2005 8:56 pm 
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Joined: Sat Feb 19, 2005 5:37 pm
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Yes I have managed to spot M57 in 10x50 binoculars, and my
skies are not that dark. Using Russian 20x60's, it is very easy to
see.
Mounting the binoculars on a support or tripod will give you an
extre half a magnitude gain which always helps.


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 Post subject:
PostPosted: Sun Jul 31, 2005 10:54 am 
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Joined: Sat Dec 11, 2004 8:18 pm
Posts: 6141
Location: Manchester
Dear al
How good your eyesight is must be a factor and age is probably comes into it though differing degrees from one person to another.
I recall seeing M57 with 10 x50 binoculars from a darker sky sites but not from my back garden. Here I reckon on a decent night I can see unaided eye stars down to about apparent magnitude +4.3. One night about a year or two back I reckonned to see stars as faint as mag +5 I could not explain those apparently exceptionally good conditions and they did not las long. I recall it happening about the time the SPA did a survey asking members about their local sky conditions. I seem to remember the exceptionally good night confused me so much that I sent the SPA a new survey form and asked them to cancel the first. Ironically since then I have never experienced such a good sky and wish I had never sent the revised form. Though to be honest M57 is not an object that grabs my attention when I am using binoculars. I agree with "A" that supporting bins on a sturdy tripod enhances the limiting magnitude by a good half magnitude. However, I personally like the freedom of using bins hand held even my old 20 x60s (although I prefer my 15x70s). Apart from anything else I find using my bins on an ordinary tripod a sod when observing at high angles, particularly as I get older and grumpier.
Using my 15x70 bins hand held in our back garden (where I usually steady myself by leaning on a wall) I seem to manage to sketch star fields down to about apparent mag 8.3 ish. M57 is a bit fainter than that and probably just my own normal observing limit but possibly just within using a tripod. M57 is a bit steep. My last serious use of bins on a tripod was Saturn but I won't go into the boring details of all that again except to mention that Saturn was at a slightly more comfortable viewing angle than M57.
Best wishes from the Grumpy Old Codger Cliff


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 Post subject: Thanks
PostPosted: Sun Jul 31, 2005 12:02 pm 
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Location: Stoke-on-Trent
Thanks for all the replies. I'll have another attempt, and perhaps have a go at sketching what I see - this might help focus my attention a bit more.

Jeff.


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 Post subject:
PostPosted: Sun Jul 31, 2005 1:08 pm 
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Joined: Sat Feb 19, 2005 5:37 pm
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Hi All

Regarding "Cliffs" reply and local seeing conditions.
The average unaided eye limiting magnitude from my
site is around mag 5.1 and on some nights each year I
get to see stars down to mag 6.0.

Stranglely, while looking back through my observing books,
I see that the majority of these excellent nights have been
in the month of August. In general August has always given
me good seeing conditions, why should this be?

However, the sky never really seems to get dark. It always
seems to have a grey murky appearance. The deep sky objects
seem to suffer the most, and trying to visually observe the fainter
DSO's is now a thing of the past for me.


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 Post subject:
PostPosted: Sun Jul 31, 2005 6:51 pm 
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Joined: Sat Dec 11, 2004 8:18 pm
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Location: Manchester
Dear "A" et al
Obviously I cannot say anything about other peoples local observing conditions I can only talk about my own experiences. However, by all accounts apart from fairly obvious variations across the sky (ie usually best directly overhead tending to get worse near the horizon) the limiting magnitude of stars wich are point source does not give a true idea of the faintest Deep Sky fuzzies one might be able to see. I think pollution, possibly both atmospheric pollution and "ordinary" light pollution affect Deep Sky Fuzzies more than point source stars. There was a good article in Sky and Telescope about this a couple of years back. If I recall corretly it was a couple from Denmark who devised a special metering device to measure how light pollution affects Deep Sky fuzzy objects. I thought about making one myself but took a selfish view that the sky monitoring would take too long to come up with any definitive answers and by then I might be passed observing. Anyway to produce results that might influence national government would not only take a long time but need more than a few cranks like me to make them see sense. So I decided to just make the best of a bad job and observe whilst i still can do.
I reckon going back about 20 years I could get a decent glimpse of the Milky Way from here on say half a dozen nights a year. Now the Milky Way is as good as gone. Admittedly my own eyesight may have also declined a bit in the meantime as well, I nwow wear reading glasses, I did not wear any specs at all 20 years ago.
Best wishes from the grumpy Old codger Cliff


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 Post subject: M57 and expectations
PostPosted: Sat Aug 20, 2005 7:54 am 
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Joined: Fri Dec 03, 2004 12:51 pm
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Location: Stoke-on-Trent
Hi all,

Unfortunately I don't have access to a 10x50 binocular at the moment, to have another go at this exercise, although from previous observing notes (using an old pentax 10x50) I don't have a recollection of seeing M57 from my observing site in this binocular. However, despite having the Moonlight and heavy city light pollution to contend with I thought I'd have a go using an 8x56 binocular, and then my 25x100 - given that it was a cloud free night - and compare the difference. I've also been trying to record what I see at the eyepiece, more recently, as part of my observing notes, so I had a go at mapping the stars that were visible, as shown below.

M57 was clearly visible in the 25x100, as would be expected, but not in the 8x56. I hadn't expected to see it in the 8x56, as this may be asking too much of 8x magnification. I'd recently tried to view M57 using the 8x56 from a dark sky location in Scotland, but I was unable to see it. In the 25x100 M57 was still like a small out of focus star, as previously described, and it looked more distinct using averted vision. As soon as I have access to the 10x50 I'll have another go, and preferably on an evening when there is no Moonlight. I always find it interesting to note the faintest stars that I can see when I'm observing, and whilst I haven't captured every star I believe that the 8x56 picked up +8.06 HIP92860, and the 25x100 picked up +9.94 TCY2643-02170-1 (according to my comparison with Cartes du Ciel). Given my city location, and the fact that Moonlight was washing the view out at 00:30BST, I didn't think that this was too bad. The white inner circle on the 8x56 diagram shows the approximate field of the 25x100 view.

Image


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 Post subject:
PostPosted: Sat Aug 20, 2005 9:05 am 
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Joined: Wed Jul 28, 2004 6:43 am
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Hi

All this begs the question as to whether your 10 x 50 binoculars are really 10 x 50 anyway. If you read the article in the last Sky & Night magazine in which they report on tests of 10 x 50 binoculars you will find that in half the cases rather than having an exit-pupil of 5mm as 10 x 50s should have (divide 50 by10) the exit pupils were smaller, meaning that the design in some way 'stopped down' the aperture. Exit pupils were measured as 50mm (ok), 4.3mm:3.8mm and 4.0mm. This means that half of the binoculars tested (including Helios and Celestron) were in reality only as about 10 x 40 binoculars. It makes you think doesn't it?

Mike


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 Post subject: M57 and expectations
PostPosted: Sat Aug 20, 2005 9:28 am 
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Location: Stoke-on-Trent
Hello Mike,

Yes, that's a fair point, the 10x50s that I have used in the past are not particularly high quality. I did read the Sky At Night report, and it was an interesting read. Funnily enough, at the time when I bought my 8x56s I tried quite a range of binoculars before selecting the 8x56 pair. I remember being shocked at the seriously poor quality of some comparitively priced well know manufacturer models.

Jeff.


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 Post subject:
PostPosted: Sat Aug 20, 2005 8:04 pm 
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Joined: Sat Dec 11, 2004 8:18 pm
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Location: Manchester
Dear al
I am sure that Mike is right in what he says about the BBC Sky@Night mag binoculars test report.
Even so, if I had bought some cheap and nasty bins I would not necessarily worry myself too much. As a friend says, the best telescope is the one that gets used the most, and I think the same applies to binoculars.
According to S@N one binoucular(Bresser travel costing £50 provides a 5mm exit pupiland so gives a full 50mm aperure but only gets a 55% optical rating in the test. Whilst the cheapest bins tested (celestron UpClose) at only £25 supposedly only provides a 4.3mm exit pupil (ie equivalent to bins of only 43 mm aperture, but the optical quality is 56%.
So in practice are the cheap half the price bins that desperately inferior.
There is another point which I am not sure how much it might affect things.
Young people whose pupils are wide open possibly as much as 7 mm.
But that may only apply at a dark sky site given light pollution even the best eyes might go down to 5 mm possibly less. They say that someone of 60 years of age, might have only 4mm diameter pupil eyes.
I (significantly beyond that age) personally find my 20 x60 bins (ie 3mm exit pupil) better than using my 10x50s . Of course it is possible my 10x50s are not as good a quality as they should be. I have some 15 x 70s (ie supposedly 5-ish mm exit pupil). I like using the 15 x70s best partly because they are more comfortable to handle than the 20 x 60s. However, the 20 x60s do seem to provide a darker sky background than the 15 x 70s. Of course I live in a fairly light polluted place, on the other hand the actual quality of the two bins could be a factor.
By the way in the good old days I think Patrick moore used to recommend using 7 x 50 bins (ie 7 mm exit pupil) biut nowadays i think he recommends 10 x 50s (5mm exit pupil) and that is possibly because of increases in light polluton.
Please note I make definitive suggestions, I have only made comments which I think are related to this interesting topic.
Best wishes from the Grumpy old Codger Cliff


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 Post subject: Re: M57 and expectations
PostPosted: Mon Aug 22, 2005 8:52 am 
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Location: South Lincolnshire
jeff.stevens wrote:
The white inner circle on the 8x56 diagram shows the approximate field of the 25x100 view.

Jeff. I do like the look of those images. Can you say more about how they're produced?

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 Post subject: Lyra Drawings
PostPosted: Mon Aug 22, 2005 5:38 pm 
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Joined: Fri Dec 03, 2004 12:51 pm
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Location: Stoke-on-Trent
Thanks Dave. They are pencil drawings on a pre-drawn template, which were then scanned and colour-reversed.

I constructed the original template in MS Word, fitting 6 onto an A4 page. The centre circle is white on a black border, with a text box below containing black text on a white background. I scanned the final drawing at a resolution of 600dpi and saved it in JPEG format. I used a freeware product called XnView to reverse the colours into a negative image and to reduce the size to 800x471 pixels. I then used MS Paint to add the white circle and M57 label.

I've only recently started sketching what I see at the eyepiece; inspired by the drawings of others I've seen on here like Joe, yourself and Cliff, and also those in the SPA News Circulars and quarterly magazine. The accuracy isn't there yet, but it's interesting to do, and has definitely helped improve my observing skills. I think it slows the observing session down too, rather than rushing on to look at another object I'm actually enjoying studying something in detail and getting a great deal more out of it. The binoculars were tripod mounted when I was doing this.

Jeff.


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