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.