Gather or transmit more light to your eye

TXCOONDOG

Highlands, Texas
Some information that is good to know:


A 50mm objective does not gather or transmit more light to your eye than a 40/42mm objective in a 1" tube. It is the the exit pupil and the light transmission quality of the glass that determines low light visibility and what you can see at sunrise, sunset, and at night. The exit pupil should be as large as the human eye under the same conditions. The exit pupil is calculated by dividing the objective diameter by the power setting on the scope. At night a 42mm objective scope set on 6 power will give you a 7mm exit pupil which is optimal and matches your eye and transmits the maximum light the eye can see.


From Nikon: "As far as 30mm vs. 1", they do not gather or transmit any more light than a 1" scope, but they provide a larger sweet spot to enhance resolution."


From Leupold: "The key to a scope providing a bright image to the shooter is not how much light it "gathers" but how much usable light it transmits. "Gathers, transmits, what's the difference?" Quite a lot, actually. First of all, rifle scope do not "gather" light, they transmit it. Yes, large objective scopes allow more light to enter the scope, but that by itself does not guarantee that the image will be any brighter than a smaller objective scope's. In other words, the better the glass and coatings you get, the better your night hunting."


Since a healthy eye pupil is 7, think in numbers of 7:


First number represents magnification setting, 7 represents healthy exit pupil, last number is your objective lens size.


1X7= 7MM
2X7= 14MM
3X7= 21MM
4X7=28MM
5X7=35MM
6X7=42MM
7X7=49MM
7X8=56MM
 

Ratdog68

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We have stickage... we have stickage folks. Good find.
 

rob072770

Lewisville NC
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I love to learn new stuff
 

pruhdlr

Cantonment,Fla.
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I have been using the basic formula for some years now. The way that I heard it is the younger eyes will dilate down to 5mm,for us ol' farts use the 7mm formula. I used this while night hunting coyotes in Maine. The typical was to drag a road kill deer out onto a frozen lake with my snowmobile,then build a snow shelter on the bank and hunt the full moon,clear nights. I would actually crank back the power setting as the ambient light faded. I do the same thing night hunting in Fla.

I will say though, that a 30mm will give you more field of view and allow you to track a moving target somewhat better. --- pruhdlr
 

PRyan1877

Roselle, Illinois
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This is good useful information. Thank you for sharing it with us.
 

BigRedDog

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Not sure that I follow the reasoning.

Don't know that I agree.
 

Drift

LSB Member
Pruhdir is right in that older eyes don't see in the dark as well as younger eyes. Where he is mistaken is that older eyes do not dilate as much as younger eyes. So 5 mm is about all the light older eyes let in; so any light> about 5 mm is wasted.
 

rob072770

Lewisville NC
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Well,that explains a lot and my eye Doc told me that cataracts have started. Typical for my young age Ha Ha.
 
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