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Re: [at-l] Binocs???

Kahley
Lens coatings are used to reduce light reflection at the lens surfaces in
cameras, binoculars,etc.  This not only increases the brightness of the
image, it also increases the contrast of the image by reducing light
reflection and scatter inside the optical system.
The lens coatings usually consist of layers of such materials as magnesium
floride vacuum deposited on each lens surface exposed to air.  Multiple
layer coatings are superior to single layers and are used in high quality
instruments.  I've seen the ruby coatings on cheap binoculars and I think
they're only single coated since the surface reflection is so bright.  The
reflection off the lens of good binoculars are quite weak and rather
neutral in color.  Also, make sure that ALL the lenses are multicoated, not
just the front ones.
Apparently these titanium binoculars have objective lenses only 10mm in
diameter; this severely limits their light gathering capacity and I would
expect that the brightness and contrast of the images would be poor,
particularly on overcast days.  Most ultralight binoculars have objectives
of at least 20 mm which gather about four times as much light,and they are
still marginal .
I suspect that the gimmick is the 6 oz weight; the manufacturers reached it
by shrinking the size of the optical components and the  best coatings in
the world can't make up for that, in my humble opinion.
You can find a lot of good stuff on binoculars at the following websites:

www.birder.com/mall/index.html

www.gwi.net/sing/bvd.html

time for a walk.....

Duane Younglove
Merlin 96
----------

> Binoculars....
> I've had a bunch over the years...Big and heavy, monocs weighing 1oz.,
> 'spy' scopes of 12 power that needed to be set in cement to steady them.
> The newest ones I'm considering are TITANIUM 8X10 under 6 oz (or so I'm
> told) with ruby coated lenses.  Is this coating a gimmick?  What is it's 
> purpose?  Thanks		Kahley
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