Astronomy Binoculars

[sourton]

Can anyone tell me what I can realistically expect to see in the night sky with a pair of 10 x 50 binoculars. Is it worth getting this size or would I need bigger ones. I have looked on some websites and they say I can see some planets and galaxies. Is this correct or are they exaggerating a bit to get me to buy them.

[carlos_dfc]

Hi

Yes, you can see plenty with 10x50 binoculars - I use a pair all the time when I'm at the telescope - they are a very handy 'bridge' between charts and the view through the telescope.

Many of the Messier objects can be spotted with 10x50s, and SEVERAL non-Messier open clusters. From a dark site, the Andromeda Galaxy (M31) is a wonderful sight through 10x50s - and can still be easily seen even from a suburban location (although,the light-pollution will kill-off a lot of the fainter details) - I've also detected the galaxies M33, M81, and M82 with 10x50s from a dark site,
You will be able to see ALL the planets if you know where to find them - although you won't see any details. like surface features, or Saturn's rings with only 10x magnification.
You will be able to see Jupiter's 4 brightest moons though, and track them from night to night as they 'dance' around their parent - you'll be able to see the phases of Venus, when it gets at a good sideways elongation from the Sun, you can see crescents etc, just like a tiny version of the Moon - Neptune and Uranus will only appear as blue-ish dots though, you'll see them, but no shape or detail.
Asterisms like the smiley-face in Auriga, and the Coathanger cluster - as well as open and globular clusters - The Pleiades, and the Beehive are beautiful in binocs - Perseus double cluster is another treat - and LOADS of other clusters are visible. Cygnus and Cassiopeia in particular are very rich in binocular-visible clusters - There's also the Milky Way star-clouds, to the South in Sagittarius (a summer treat)

Bigger binoculars are even better - a jump to 15x and maybe 70mm or 80mm aperture will show even more - a hint of Saturn's rings, the main two cloud-bands on Jupiter - my 15x70s will show galaxies M81 and M82 even through average suburban light-pollution.
Celestron 15x70s are available from Argos fro about £80 - probably the best bang-for-the-buck available in binocs.

Whatever you do though - AVOID ZOOMS like the plague - a zoom binoc that is good for astronomy has never yet been made.
Also - in the spec - look for Bak-4 prisms, as opposed to Bk-7 - much better light throughput.
And avoid anything with red or yellow lens coatings - as a general rule of thumb, decent anti-reflection coatings usually have a faint green/blue/or purple tint.

[sourton]

Wow, Thanks very much for that Carlos, I am going to see what I can afford to spend and have a look around for some. Hopefully I might get a bargain in the sales. Thanks again

[Beryl]

I have 20X50 discovery bins and can see jupiter and it;'s moons. Very small mind. but still quite breath taking

[Tormentil]

After reading carlos's post, I might just dig out my old 10 x 50's and have a go. I should imagine that they 'll need to be tripod supported to avoid shake (my Ziess Jenoptems get a bit heavy to hold after a while).

[earthman]

Hi everyone, just found this site by accident via google, was looking for info on binoculars.
I am thinking of buying a larger pair, the only ones I have are 10x25, only really used them for general sight seeing when on holiday etc.
I like the idea of the Celestron 15x70 but I dare say they are too big and heavy to be carrying with you on holiday? Can you get that size of magnification in say the typical overall size of a 10x50 binocular? Would a 10x50 pair give the same magnification as my 10x25, ie 10, does the 50mm lens add in anyway to the magnification or just let more light in?

I dare say i want the impossible, a light weight pair with enough power to see the moon,aircraft,mountains etc in great detail.

Anyone know if the pair below are any good to start with? If I knew for sure that they would get a lot of use then maybe a Bushnell waterproof pair for around the £100 mark would be a good starting point?


Praktica 10 x 50 Birdwatching Binoculars only £39.99 at JellyDeal.co.uk - compare ¦ buy ¦ save

[earthman]

Forgot to say, what great advice/info from Carlos, just wondering about zoom binoculars, why are they no good for astronomy?

[carlos_dfc]

Hi

On the subject of 10x50 versus 10x25..
Yep, the magnification is the same, the 50mm objective lenses let in 4 times as much light as the 25mm lenses (you square the diameter in mm to compare light-gathering ability)
25mm lightweights are good for daytime use, but in low light - or for astronomy purposes, 50mm binocs will be streets ahead (assuming similar quality)

On the subject of zooms..
A few major reasons why they're bad for astronomy.

First off - the field of view in zooms is much narrower than in fixed magnification binocs - making it much harder to navigate your way round - and restricting your wide views of Milky Way starfields and large Deep sky objects like the Andromeda galaxy.

Zoom mechanisms require many more pieces of glass, than fixed magnification - and every piece of glass that the light goes through, diminishes the brightness of the image (all-important for astronomy) - for example, a 60mm zoom will probaly only give images as bright as the average 50mm fixed mag binocs.

Zoom mechanisms are also VERY difficult to build accurately aligned - and as the power goes up - the finer the tolerances required become - as a result, the alignment of the two images is usually only ever *good* at low powers - as you zoom, the alignment wanders.
In daylight, this isn't so much of a problem - your eyes and brain can merge slightly mis-aligned images, if the have sufficient light to work with.
At night, you can never merge the bad mis-alignment that you get at high powers in zooms, and the slight mis-alignment that you get at low-powers, will give you a headache within 10 or 15 minutes of viewing.
To manufacture an ACCURATELY aligned high power zoom binoc, would cost so much, that they would only appeal to a specialist market - and a low production run would just shove the price up even further - so none of the manufacturers bother, and all we see are cheapies, which are frankly awful.

I actually own one pair of zoom binocs (10-30 x 60mm) which I keep for the sole purpose of reminding me never to buy another zoom binoc - If I'm ever tempted - one look through those, and I come bac to reality.

[earthman]

Thanks again Carlos for the info, sounds like you have looked through many pairs of binoculars.

Anyone bought a Praktica product? Just wondering if I should give there binoculars a try?

[carlos_dfc]

Yep - loads - LOL

The one pair of compact bins that I own, are Praktica, and in the past I've had a few Praktica lenses for 35mm cameras - in my experience, their optics are generally pretty good.

[nightshade]

Just out of curiosity(I do not fully understand the criteria for
astronomy Binos)I looked for some big magnification Binos
4-under £100 Microglobe home of photgraphic equipment in UK
Microglobe home of photgraphic equipment in UK

[carlos_dfc]

Originally Posted by nightshade

Just out of curiosity (I do not fully understand the criteria for
astronomy Binos)

Hi Nightshade...

A few of the important things to consider when buying binocs for astronomy...

Don't get carried away with magnification - more is not neccesarily better. When you get above 12x magnification, you need to mount the binocs, tiny movements when hand-holding may not be a big deal in daylight - but when you are near the limit of your eyes' light sensitivity, trying to see the maximum amount of dim stars or dim deep sky objects, those tiny movements will mean that you fail to see A LOT that you would see if the binocs were steadied. And at higher powers, you also need the aperture to match, otherwise you get dim images.

Exit pupil
This is the diameter of the cone of light that leaves the eyepieces, and enters your eye.
It is easy to work out, just divide the aperture, by the magnification...
A 10x50 will give a 50mm /10 = 5mm exit pupil
8x56 gives 56 / 8 = 7mm exit pupil
Again - during the day, exit pupil isn't a big deal - a daylight scene will usually give plenty of light throughput, even with a small aperture, and also a small exit pupil.
At night it's another matter - most people's pupils will dilate to somewhere between 5mm and 7mm wide - so the wider the exit pupil the binocular has, the more light it can supply to your eyes. As a general rule of thumb, for astronomy you want binocs that give AT LEAST a 4mm exit pupil - preferably 5mm - 7mm (more than 7mm is a waste - most people's pupils won't go any wider than 7mm.

Aperture
The size of the front lenses - Bigger is better, because the surface area of the main lens dictates how much light the binocs can draw in. A 70mm binoc will draw in about twice as much light as a 50mm binoc (you square the diameter when comparing surface area)

Coatings
Lens coatings reduce the amount of light that the glass reflects - no glass lets through 100% of the light that strikes it, some light is always reflected away - and anti-reflection coatings can mean the difference between 94% throughput, and 98% throughput (PER LENS ELEMENT) - 4% doesn't seem much, but when you consider that the light has to pass through usually about 5 or 6 lenses, and 2 prisms, it all adds up. Coated optics are OK - Multi-coated is better - Fully coated is better still - and Fully Multicoated is best.
The colour of the coating is also a big clue, the best coatings usually have either a blue, purple, or green tinge.
Red (Ruby) and Amber coatings are to be avoided.

Prisms
Porro-prism design is best - Roof prisms are often OK, but are more difficult to manufacture well aligned - so cheap roof-prisms are to be avoided.
Prism material - BaK-4 is best, avoid BK-7 (BaK-4 has a much higher light throughput)

If two binocs are of similar spec, quality, and price - go for the one with the widest field of view - the wider your view, the better for navigating your way around.

And as mentioned above - for astronomy, zoom binocs are the Devil incarnate.

Best binocs for astronomy for under £100 are probably Celestron's SkyMaster 15x70
Other good sizes... 7x50 - 8x42 - 8x56 - 9x63 - 10x50 - 10x70 - 12x60 - 20x80 - 22x100 (HUGE)

Personally, I'd avoid 16x50s, 20x50s mainly because of the small exit-pupil - I've owned a 20x50, images were too dim for astronomy.
(I also have a pair of 4x28 opera glasses - great for low-power sweeping round when at a dark site - Lovely bright images, I much prefer those to a 20x50)

I think that's about it - any questions just ask and I'll try to clarify

[earthman]

Well I took the plunge and bought those 10x50 from Argos, used them last night to look at the full moon, I think they are not bad for the money but I've only got a cheap 10x25 to compare them to.
I'm now tempted to exchange them for the 15x70 skymaster but weighing in at 2510g I'm not sure, this pair feels heavy enough at 965g, I'm not sure I'll be taking these with me on walks,holidays etc. Paying another £10 to get the tripod with the skymasters would be a must I think.

So the question is how much more am I likely to see with another 5x magnification?
Would I be better off buying the 660x powerseeker telescope for £80? I think both instuments would stay at home due to their size/weight, although either one would have to be setup and taken down outside the house every time I wanted to use it, is this more difficult/involved with a telescope?

Originally I thought that one pair of binoculars would do but I guess that most of you end up with several different sized pairs. Carlos, which of your pairs do you use for each activity/use/holidays etc?

[carlos_dfc]

Hi Earthman

First of all - don't even consider the celestron Powerseeker telescope.
It isn't actually made by Celestron - it's actually a re-badged far-eastern make. Celestron & Meade both license their names out in this manner - DON'T buy a SMALL telescope in either of those brand-names - the BIGGER Meades and Celestrons are actually made by the proper parent company.
Another thing is to never buy a telescope that uses stupidly high magnifications in the model name or advertising.
Any telescope's MAXIMUM magnification is dictated by the diameter of the main lens or mirror.
The laws of physics only allow about 2x of magnification per mm of aperture.
So those 60mm telescopes are only really capable of 120x magnification - 660x is an absolute JOKE
Imagine a digital image - if you keep zooming in - eventually you will begin to see the individual pixels - further zooming won't show any extra detail, it just makes the pixels bigger.
Well it's a similar principle with optics - any more than 2x per mm gives you 'empty' magnification - the images do get bigger - but you don't see any more detail, all you are doing is accentuating the deficiencues in the optics.
A nice crisp image of Saturn and rings, at 110x, will become a (6 times bigger) dim, fuzzy 'blob' at 660x.

The best balance of quality, at a reasonable price, for telescopes in UK is the 'SkyWatcher' range - they do a refractor with the same spec as the powerseeker, but FAR better optics, for only £55

Binocs
The extra 5x won't make a big difference to daylight viewing (Images will obviously be 1.5 times bigger)
But at night, the extra size of the objectives in the 15x70s makes a HUGE difference to what you can see.
You will need a tripod for the SkyMasters, compared to 'normal' binocs, they are enormous.


As for what I use, and when...
I like to use 10x50s as a companion to a telescope - I have a big set of star-charts (Cambridge Press 'SkyAtlas 2000.0') and the 10x50s show pretty much exactly the same stars, that are marked in that atlas - so they are great as a sort of 'bridge' between charts and telescope. Using chart and binocs I mentally note where an object is (sometimes binocs will show it faintly - sometimes not) beofre searching with the telescope - makes star-hopping to dim deep-sky objects easier.
10x50s are also the general-purpose bins I use while on holiday etc..

15x70s are used for sweeping around star-fields, clusters etc - they'll alos show some detail in the bigger and brighter deep sky objects - most of the Messier list is within their reach, and a host of NGC-classified star-clusters.
I use them if I only have a short time available for viewing, and don't want to set up a telescope.

20x50s - I use as daytime 'spotters' (mounted on tripod)
Images are too dim for astronomy, but in daylight, the extra power is handy for things like birdwatching etc..

A compact pair (10x25) is a handy daytime compromise if I can't carry full-size 10x50s with me.

I have other various sizes, but they get much less use than those I've already mentioned - an 8x56 pair get used as a good low-power companion to the 15x70s sometimes - and I also keep an extra pair of the 'Lidl' Bresser 10x50 specials permanently in the car - so I ALWAYS have a decent quality general purpose binoc with me, and if they get banged around in the car, at £9-99, it's no tragedy

[earthman]

Many thanks Carlos, don't you just hate it when a company allows their name to be used on inferior products, should be a law against it!

What would be the procedure in setting up a telescope and how long does it take?
Do you think I would be better off with the skymaster binoculars, assuming that it's just a case of screwing them to a tripod?

[earthman]

Well I don't know if I done the right thing but I did buy the skymasters & a tripod, So far I am very pleased with them.

[carlos_dfc]

Just a quick heads-up....

The 10x50 Bresser binocs I mentioned - are back on sale at Lidl shops, from Monday the 23rd of April.

Lidl Online

They really are a FANTASTIC bargain at £9-99 - I'm not exaggerating when I say they are better than some £50 binocs I've used.

If you want a pair, be there early on Monday though - they are very well known among astronomy and birdwatching forums - they usually sell out fast.

[wildlifesnapper]

thanks for the info Carlos.

Looks like I'm walking to work on monday then so my wife can get there early

neil

[arvensis]

Thanks for the heads up Carlos, I will buying a pair for myself if I can get hold of a pair! 5 year warranty as well so it can't be bad.

Mark

[wildlifesnapper]

Hi

got a pair of the Bresser from Lidl today.Had a look through them and they are great , nice and sharp.For £10 they're a bargain.

Thanks again for the tip-off Carlos.

neil