Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Binoculars Previous   Index   Next   Flat   neoweb Pooh-Bah Reged: 12/10/06 Posts: 1482 Loc: UK What does the 'Visibility Index' tell you?       01/03/07 11:51 AM Edit   Reply   Quote   Quick Reply:   In one of my previous binocular threads in the beginners forum, 'saberscorpx' kindly replied by saying:- "With binoculars, magnification has a much higher performance emphasis than aperture. The preferred VI (Visibility Index) Mag X Sq. Root of Aperture yields the following values: 7x35 40 7x50 50 10x50 70 10x70 85 15x70 125..." etc. I calculated the VI for some 20x90 binos and of course got 190. Excuse my ignorance, but what is a 'Visibility Index' and what does it tell you? Thanks as always. -------------------- Celestron StarHopper 8" f/6 Dob 38mm Burgess 2" SWA | 30mm Ultima | 20mm Omni 17mm Hyperion | 12.5mm Baader Ortho 8mm TV Plossl | 6mm TMB/BO Planetary Orion Shorty Plus barlow 15 X 70mm Skymasters Saturn-like: desktop image Post Extras       Entire thread Subject Posted by Posted on What does the 'Visibility Index' tell you? neoweb 01/03/07 11:51 AM Re: What does the 'Visibility Index' tell you? EdZ   01/03/07 12:06 PM Re: What does the 'Visibility Index' tell you? neoweb   01/03/07 04:51 PM Re: What does the 'Visibility Index' tell you? KennyJ   01/03/07 05:30 PM Re: What does the 'Visibility Index' tell you? patter1   01/03/07 06:20 PM Re: What does the 'Visibility Index' tell you? EdZ   01/03/07 08:09 PM Re: What does the 'Visibility Index' tell you? edcannon   01/04/07 02:58 AM Re: What does the 'Visibility Index' tell you? neoweb   01/06/07 07:16 PM Re: What does the 'Visibility Index' tell you? EdZ   01/06/07 08:06 PM Extra information 11 registered and 15 anonymous users are browsing this forum. Moderator:  EdZ  Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Rating: Thread views: 370 Jump to *International Year of Astronomy 2009* -----   Global Coordination   Cornerstone Projects   Special Projects   Special Task Groups   Global Activities   National and Regional Activities   IYA 2009 in Africa   IYA 2009 in the USA*Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Beginners Forum   Celestial Events   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Celestron SkyScout and Meade mySky   Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   General Observing   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Other* -----   Science of Astronomy & Space exploration   AstroWebsites   Space Rocks*Speciality Forums* -----   AstroArt   Astronomy Software & Computers   Stellar Media   Astro Outreach, Clubs and Star Parties*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements Home

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