Binolulars Help

[ownjoouk]

Hi all,

I'm looking at buying some binoculars for the mother in law for xmas. These will mainly be used for bird watching, but I was thinking I could use these as a finder when we take the scope out as they are usually left in my car (and also allows for the wife to be looking at stuff while I mess with the scope).

Anyway, I'm on a bit of a tight budget (times are hard!) and was wondering if these would be any good?

http://www.scopesnskies.com/prod/binoculars/high-powered-binoculars/Pentacon-high-powered-binoculars/bresser-cobra-20x50-porro-high-powered-observation-binoculars.html

Remember, they won't be used as much for Astronomy. I don't know much about binoculars so any advice would be appreciated.

Thanks.

[GazOC]

They may be a little high powered, look for something x10, x8 or x7.

[Viking]

I think the 20x magnification would be difficult to hold steady.

10x50 or less would prove better in the long run, especially for normal terrestial use.

Like any other optical device, you get what you pay for.

Auntie FLO has some celestron on clearance. Seems like good price reductions.

http://www.firstlightoptics.com/products.php?cat=93

Good luck with your purchase.

John

[argonaut]

I would probably go for a 8x42 binocular. It seems to be a good general purpose size. When you go to higher mags it does introduce shake.

Good Luck with your search.

Argonaut.

[philsail1]

Hello ownjoouk,

If you have a "Jessops" store near you, you might want to take a look at these:-

http://www.jessops.com/Store/s49866/0/Binoculars/Centon/8x40-ZCF-Binoculars/details.aspx?&IsSearch=y&pageindex=1&CatId=3610&ManIds=1164,1288,1470,&MultiOpIds=19,28,&SortBy=SkuOfferingPriceASC&IsInStockOnly=False&comp=n

I have looked through them, and the views are very good for their rediculously low price.

As the others have said - I would tend to go for an 8x40 or 8x42 binocular.

They are nice and light to hold. Give a reasonable manification, and bright image, and they have good eye rellief and field of view.

You cannot beat trying a binocular "in the flesh." They have got to feel right when you hold them.

Best wishes,

philsail1

[The Warthog]

Most bird watchers use binoculars in the 7x to 10x range. Those 20x binoculars will be heavy, hard to hold steady, and difficult to aim, as they have such a small field of view.

[Astronut]

I wouldn't go much higher than 10x (up to x15) magnification for hand held use because, as the others have said, using a higher magnification will make it difficult to keep the image steady. Forget the one's in the link you've posted unless you intend to use a tripod or monopod. Some use 15x70's handheld successfully but these can get quite heavy depending on the make and model introducing shaky images.

Another thing to consider is the size of the exit pupil - that's the size of the disc of light you can see at the eyepiece as you hold the binos at arms length with the objectives against a lit background. Ideally this should not exceed 7mm in diameter or 6mm if you're older (eye pupil dilation decreases as we get older) otherwise the full amount of light leaving the eyepieces won't enter your eyes and you'll be wasting some of the light collected by the objective lenses thus reducing the effective aperture.

It can be calculated by dividing the objective diameter (in mm) by the magnification.

For daylight use eg. birdwatching, the exit pupil should be ideally a little smaller than this because your pupils won't be dilated to max. Personally, I would choose an exit pupil of approx 5mm or less.

A pair of 10x50 binos would give you an exit pupil of 5mm (50mm objective lens diameter divided by 10).

A pair of 8x42 binos (as recommended by Glen above) would give an exit pupil diameter of 5.25mm (still good) but these would be lighter,

easier to handhold and therefore steadier images with not much decrease in magnification.

Not relevant in your case but if you regularly observe the night sky from a dark site where your eye pupils can get fully dilated then a 7x50 might be better (a quite large exit pupil of 7.1mm) to give slightly brighter views and they're easier to hold a steady image at the expense of some magnification.

For astronomy, 10x50 for handhelds is a popular choice or if you want more magnification then 15x70 but be prepared to mount a pair of 15x70 if they're a bit on the heavy side.

Also go for a pair that at the very least have some sort of anti-reflective coatings on the objectives and eyepieces. Most pairs do these days but some coatings are better than others (eg. fully broadband multi-coatings on all lenses and prism surfaces) which can push the price up.

Also, if your mum-in-law wears glasses then aim for a pair that gives long eye relief (eye relief is the distance from the eyepiece lens surface to the eyeball) or she won't be able to see the whole field of view. Anything which offers useable (remember that the eyepiece lenses are usually recessed taking up some of the total available) eye-relief of about 12mm or higher should be OK for most glasses wearers and most binos have fold down rubber eyecups for glasses wearers.

Sorry I've waffled on a bit but I've been reading alot on binos recently and I'm suffering from info overload

ps. it's generally recommended to avoid zoom binoculars like you would the plague.

[iancandler]

One of our regs has some Celestron 10x50's with light polution filters that can be swiveled into place in the for sale section at not much more than the new price of the practika's

[centroid]

I have a pair of 10x50's and a pair of 15x70's, and without doub't the 10x50's are the best for general use. Not too large or too heavy, and not difficult to hold steady.

The 15x70's, which I use for astro only, are large, heavy, and best when mounted on a tripod.

Dave

[Neon]

What Dave said 8)

I've got some 15x70's and they're not so good for general use, but when braced or mounted on a tripod they're superb.

I reckon 10 or 12x mag is about the most you can realistically use purely hand held, and what you need to remember is that clarity is king, not magnification. If the binoculars aren't very good you won't see anymore at 20x than you will at 10x.

For the price you're looking at here's what I'd go for:

Adler Optik Witness 10x50

Or like Ian says there's a pair for sale on our forums, or you could put a request in the wanted section.

HTH

Mark

[ownjoouk]

Thanks all for your responses, I'll take that all on board before making any purchases.

[beetlejuice]

I would echo the sentiments re. high-power binoculars. I have a pair of Practica 20x50's. They simply don't get used due the relatively small field of view, weight, and consequent shake. 7 or 10 x50's are ideal IMHO.

[thing]

The ones I use the most are my 8x30's. The 15x70's have to be tripod mounted.

[russ]

I'll give a vote to 8x42, mainly from a birdwatching point of view. Mum is into birding and the kids and I tag along sometimes. I take along my collection (10x50 and 15x70) but mum's 8x42's are just perfect. Neat and compact, lightweight but a bright sharp image. The sort of thing you don't mind carrying all day long and holding for prolonged periods of time.

We've used them for a spot of stargazing and they do fine on that too. Low powered binos don't really hold my attention. Very rarely use my own 10x50's.

[rusirius]

For birding and nature you need something lightweight enough to carry hung around your neck for an hour or two while walking and a compact pair of 8x42s is considered ideal - reasonably powerful, compact and not too heavy. Since you are considering some astronomical use, a pair of 10x50 might be a good compromise, adding that little extra magnification but also a little extra - but not too much - weight. Anything bigger will probably be too heavy to carry around for extended periods of time and too powerful to use steadily handheld.

From an astronomical point of view, even a pair of 8x42 will allow you to see far more than you can with the naked eye.

[The Warthog]

My first view of the Beehive was through a pair of 8x21 hiking binoculars, so any binoculars will serve to some extent.

[TheThing]

I have a pair of the Bresser 10x50's that Lidl sell for £10 sometimes and telescope house have for £24.99 (not bad at either price!)

I use them for birding - first time out saw my first Spoonbill at Langstone Harbour/Farlington Marshes. They are not to heavy and give an excellent clear image. I've also used them for astronomy and find them very good for that as well. They are highly thought of on the S@N forum and I can concur with that!

[Viking]

In view of the subsequent posts I would like to "bump" my suggestion regarding the

clearance prices on some of the celestron range from FLO. Seems like good price reductions.

http://www.firstlightoptics.com/products.php?cat=93

John

[Napoleon]

There is one point that always seems to be overlooked when considering binocular purchase, that is 'light use efficiency'. A factor of 1 is more efficient than O. The calculation is: divide the aperture diameter by the square of the magnification, i.e.

7x50 = 50 div by 49 = 1.02

8x42 = 42 div by 64 = 0.65

10x50 = 50 div by 100 = 0.50

15x70 = 70 div by 225 = 0.31

I can be seen from the above that even though 10x50 will give better magnification, 7x50's are more efficient, and steadier.

For a good instrument for less than fifty pounds try the Helios 7x50 Seamaster range. BAK4 (recommended), water proof, fog proof and nitrogen filled.

Best wishes all.

Napoleon.

[FLO]

Welcome to SGL Napolean.

There are a number of methods used to calculate a binoculars brightness - Relative Brightness Index, Twilight Factor and Relative Light Efficiency are the three most used. But, they are all flawed because they do not take into account the binoculars design or the materials used. A quality 10x50 using the best multi-coated optics available will produce the same brightness statistics as another made from bathroom glass and plastic!

They are however useful for comparing binoculars from the same family using equal quality materials but with different apertures and magnification

[Napoleon]

Steve,

Thanks for your comments. I except that one size will not fit all. The point is that the R.L.E. calculation does exist based on mathematics as apposed to the best manufacturers materials. It must follow that inferior optics will only be even less efficient.

I have in my collection a pair of 15x70's (on tripod), 10x50's and a set of 7x50's, and they all have their place in my affections' but for general use and a bit of star gazing the 7x50's get the most use, which, I think, is going back to the original question in this forum.

Good debate though!

Napoleon.

[FLO]

The 7x50 will be comfortable and bright though some might consider it a bit large for birdwatching. I'd probably opt for the more compact 8x30 or 8x40. Its a very subjective choice though

[Viking]

Steve was clearing WO 8x40 bins. Just received them today, had them out tonight. The views are stunning. The only issue is the price. But I would recommend them, 1.6 lbs weight makes for comfortable viewing.

If you want to keep on the right side of the MIL then you can't really skimp!!!

John