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TOPIC: Binoculars
Blobrana


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RE: Binoculars
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The 'twilight factor' can be calculated by first multiplying the magnification by the objective lens diameter and then finding the square root

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Blobrana


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New Website Reviews Waterproof Binoculars

WaterproofBinocularsReview.com is a new site providing reviews from waterproof binoculars buyers taken from many websites to help other consumers take smart buying decisions.
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Blobrana


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Understanding Binoculars: Magnification



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Blobrana


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Binoculars Vs. Telescopes

 

Binoculars for Astronomy

 

10x50 Astronomy Binocular Kit



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Blobrana


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How Do They Do It?- Binocular Lenses



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Blobrana


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2011 Binoculars.com Binocular of the Year Award Winners:

  • Binocular of the Year: Bushnell 10x42 Legend Ultra HD
  • Best Birding Binocular: Nikon ProStaff 7 8x42
  • Best Hunting Binocular: Steiner 10x42 Predator Xtreme
  • Best Travel Binocular: Zeiss Conquest 10x25 B T Compact Binoculars
  • Best Astronomy Binocular: Zhumell 25x100 Tachyon
  • Best of the Best Award: Swarovski 10x42 EL Swarovision  
  • Excellence in Service Award: Leica Binoculars

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Blobrana


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Porro prism binoculars
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Standard roof prisms have several inherent design difficulties. First, they are not as bright as Porro prisms because they employ mirror surfaces that lose some light. Second, alignment is often more critical than in Porro prisms; an alignment error a fraction of the width of a human hair will degrade the image in a roof prism. Securing them in binoculars is much more of a challenge. Third, images are split and then rejoined slightly out of phase when they pass through such a prism. This produces an image of slightly less resolution than an equal quality Porro prism.
Thus we have a trade-off: the slight optical superiority of the typical Porro prism versus the comfort factor of the standard roof prism. Yes, average quality Porro prisms tend to give a sharper image than standard roof prisms. There is a price to pay for comfort.
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Better Porro prisms binoculars are made from a high density glass, BAK-4. If you hold binoculars away from your eyes and up to the light, you can see the circular exit pupils in the eyepieces. The less expensive BK-7 prisms will have squared-off, non-circular exit pupils.
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Blobrana


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RE: Binoculars
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Zhumell 20x80 SuperGiant Astronomical Binoculars



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Blobrana


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Explore space with binoculars

It is well worth a step outside the next clear, dark night, despite the late-autumn chill. Even a few minutes with eyes alone will allow you to sweep across half of the universe all at once - given you are in an open field or out on a lake, or maybe on your rooftop.
Be sure to allow a few minutes to let your eyes adapt to the darkness; you can do this in the warmth of your home, with the lights off.
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