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Size of dark adapted eye pupil

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Hello stargazers,

I am looking for a way to find out the size of my dark adapted eye

pupil. There are tables with pupil sizes depending on the age but I

don't trust them. The reason for my question is: I want to buy an eyepiece for my scope with a matching exit pupil to my eye pupil.

Any suggestions?

Best regards & CS


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wouldn't that be hard to judge ?, most astronomers know it takes about 20 mins or so for there eye's to adapt to the dark, if a pupil expands to the level of darkness around us, that level have to be constant in all directions for the pupil to stay the same size. but if light levels differs, lets say you look in a direction where there is a faint light source, your pupil would adapt to that light sourse, and the reverse would also be true, if it went darker the pupil would expand, plus adding to that everyone has diifferent eyes. Could anyone really measure the true size of a pupil.


Edited by Si W
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you can measure your pupil during the night in this way:

1)take a hexagonal key set.

2) look at a bright star with naked eye

3) from the smallest to the biggest pass the key in front of your eye: if you can see the star the key is thinner than the diameter of your pupil. When you can't see the star anymore you have found the key that has a caliber as big as you pupil (or just a little bigger)



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