Light Transmission

Discussion in 'Long Range Scopes and Other Optics' started by swpc629, Jan 12, 2014.

  1. swpc629

    swpc629 Well-Known Member

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    I may have ask this question before, but my ADHD seems to have taken over. Does objective and tube size effect light transmission? Or is it just a matter of how the lenses are coated?
     
  2. theo98

    theo98 Well-Known Member

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    Larger objective sizes pull in more light and lens coatings enhance colors (such as game) that all but disappear at twilight.

    Larger tubes can offer greater mil-moa turret adjustments for long range shooting and create a more rigid scope body...however at the expense of added weight.
     

  3. Sully2

    Sully2 Well-Known Member

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    All of the above!
     
  4. bruce_ventura

    bruce_ventura Well-Known Member

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    We'll sort of. What really matters is exit pupil size. Exit pupil = objective diameter / magnification. If the exit pupil is larger than your eye pupil, the image is as bright as it's ever going to get with that scope. If the exit pupil is smaller than the eye pupil, the image has lower brightness by a factor of (exit pupil/eye pupil)squared. This ends up being a bigger effect than the typically small differences in anti-reflection coatings, especially when comparing scopes at a similar price point.

    FYI, dark adapted eyes have an exit pupil of about 5 mm (older people) to 8mm (younger people).
     
  5. lloydsmale

    lloydsmale Well-Known Member

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    for low light performance in order of importance in my opinion is first lense quality and coatings, second objective size and tube size means nothing