Saturday, 9 February 2013

watching binoculars How to pick bird

How to pick bird-watching binoculars

Author: Gregory Hui
Never forget that ultimately, picking out the best bird-watching binoculars comes down to personal preference. It's like picking a TV - there are way too many things to consider. Price, size, clarity, etc.
That said, let's get to talking about how you'll be able to spot warblers amongst the trees!
Magnification
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Most birders pick binoculars with a magnification of 7, 8 or 10 - and the way to figure what magnification a pair of binoculars has will be to look at the way they're categorized.
They're always sorted by a set of numbers that look like 7x32, 8x42, 10x50 etc. - the number that comes before the "X" or multiplication symbol refers to the magnification (i.e. 7x, 8x, 10x). It it looks like a 10-30x50, it means that it's a variable zoom that can be adjusted between 10x to 30x magnification (although I'd recommend you steer clear of those).
If you have binoculars with a 7x magnification, it will appear 7x closer. e.g. if you're 70 feet away from the object you're looking at, it will appear 10ft away. Lots of people think that the "bigger the better" when it comes to magnification, and I urge you to be wary of this. Higher magnifications have two main drawbacks -
Firstly, the higher the magnification, the smaller the field of view. Lower powered binoculars will offer a larger field of view. Essentially, this means that if you're looking at a building with a 7x power, you may only see a window with a 12x - which makes it hard to find a small bird in a big tree! Especially since birds are quite apt to jumping around in trees. Additionally, it you're look at a flock of geese in the sky, you'll see more (if not all) of the flock with a 7x than a 10x.
Secondly, when you compare 7x40s with 10x40s (this means that they've both got identical 40mm objective lens sizes - that's what the second number that comes after the "X" or magnification symbol refers to - you'll find that the 7x40s provide you with brighter, clearer pictures. This will help if you're in dark forests with limited light, or when it comes to dusk and dawn.
In addition, higher powered binoculars are typically heavier, more difficult to focus on close objects, takes more time to focus (more wheel rotations), and you will have to hold them more steady as well. Higher magnification binoculars exaggerates hand-shakes during use.
Aperture, or Objective Lens Diameter
As I mentioned earlier, the aperture a.k.a. objective lens diameter can be determined by looking at the second set of numbers in the specifications of a pair of binoculars (10x50s have a 50mm aperture size). The larger they are, the better they are to capture light, thus providing you with brighter, clearer pictures.
That said, bigger lenses equals bulkier and heavier binoculars and 50mm should probably be the biggest you should go. A good rule of thumb to ensure nice, bright images will be to get binoculars with an aperture size 5 times larger than the magnification.
Optical quality has been improving over the years, so maybe that rule doesn't hold as strongly as before, but keep it in mind especially for binoculars that cost you under $200.
Prism design
You'll find that binoculars are sorted into two main categories, based on the kind of prism systems they use: porro prisms, and roof prisms.
Porro - they have a z-shaped optical path (i.e. light path) where the main lenses on the front are offset from the eyepieces, resulting in a wider pair of binoculars.
Roof - the prisms overlap closely and the main lenses are aligned neatly with the eyepieces, resulting in a sleeker shape.
Roof prisms are typically more expensive than porro ones, simply because of the technology that goes into it. Roof prisms are also more rugged and durable, so if you're going to need a rough-and-tumble pair of binoculars, you're probably better off with roof binos. An equivalent optical quality of a roof prism pair of binos will probably cost you double what you'd pay for porro binoculars.
Personally, my favourite pair of bird-watching binoculars are the Celestron Outland LXs. You can have a look at other birding binoculars on the internet, but remember to keep these ideas in mind as well!
Article Source: http://www.articlesbase.com/bird-watching-articles/how-to-pick-bird-watching-binoculars-3637872.html
About the Author
Gregory Hui is a lover of all things to do with Binoculars! He regularly spends time looking at different Sky objects and regularly gives advice on buying binoculars as well as telescopes