Question on twilight factor how doe's one read the numbers?

Discussion in 'Long Range Scopes and Other Optics' started by Gabe V, Jan 29, 2006.

  1. Gabe V

    Gabe V Member

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    Dec 9, 2005
    Question on twilight factor how doe\'s one read the numbers?

    Twilight factor on a scope what do these numbers mean or how do you read them like on a Swarovisk PV 4-16x50 twilight factor 11-28. And on a PV 6-24x50 and a twilight factor 17-35 what doe's it mean? Thanks Gabe
     
  2. kfrye

    kfrye Well-Known Member

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    Jan 17, 2006
    Re: Question on twilight factor how doe\'s one read the numbers?

    You can send me your Swarovski and I'll figure it out for you. /ubbthreads/images/graemlins/wink.gif
    Just kidding, but I am looking for a new scope and this sounds interesting.
     

  3. Bart B

    Bart B Well-Known Member

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    Re: Question on twilight factor how doe\'s one read the numbers?

    Twilight factor is a marketing play on numbers that is close to meaningless. It's calculated by multiplying the magnification power by the objective lens diameter in millimeters then finding the square root of this product. Example: a 10 x 40 scope has a twilight factor of 20.

    Twilight factors were originally used (I think) for binoculars but have also been used for other scopes. Higher twilight factors are supposed to indicate better image quality than lower ones when used at dawn or dusk (twilight time). A higher number usually means a brighter image but not always but has little to do with image sharpmess. In reality lens quality and how they're mounted and aligned do more to effect image quality than other stuff.