What does exit pupil mean for a scope?

[feedr]

Hi guys,

Exit pupil was mentioned in another thread, starting a topic here instead of high-jacking the other thread

Like it says, what does exit pupil mean for a scope?

[Lorgar]

Stole this from the Leupold site:

Exit Pupil

Variable-power scopes also offer a light management advantage over fixed power scopes. As you change magnification, you also change the exit pupil, a measure of the light passing through the scope to your eye. Exit pupil is derived by dividing the diameter of the objective lens by the magnification of the optical device. The human eye can dilate from about 7mm for a young person in total darkness to 2mm in bright sunlight. Ideally, the exit pupil of the scope should match or slightly exceed the dilation of the eye’s pupil so that the eye receives as much light as possible.

An example of exit pupil: if a hunter goes out with a 3.5-10x40mm scope early in the morning, he can dial his scope down to 5x, and he will receive an 8mm exit pupil (40mm divided by 5x equals 8mm exit pupil). Later, when the sun is high and bright, he can turn his scope up to 10x and still receive a 4mm exit pupil (40mm divided by 10x equals a 4mm exit pupil), which is excellent for bright conditions. As evening approaches, he can turn the scope back down to 8x or so to receive a 5mm exit pupil (40mm divided by 8x equals a 5mm exit pupil) and still have plenty of light to make a shot at the end of legal shooting hours.

Ta da!

[sooey]

Lorgar is there more to that page you took that info from?

Could you link if so?

[chacka]

It's this page here mate - The Right Scope for You

[yoshie]

If the exit pupil ratio is larger than your eyes pupil, it will appear bright. Smaller and it will appear dull and dim. As the light conditions drop this ratio will affect how long you can see through your scope. When it gets dark look through your scope on high mag and note when it becomes unusable, then drop the mag down, you will then be able to use the scope for a bit longer. This is the point where the exit pupil ratio is about the same is you pupil diameter in your eye. Better scopes will have better ratios at the same magnification.

[Aussier]

Stole this from the Leupold site:

*gasp* theif!!!



J/K, good write up for a lot of the scope terms on that Leupold page.

[feedr]

Thanks for the link and the extra info guys.