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How to tell your pupil diliation?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 08:17
windstrings View Drop Down
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Its hard to know which model to choose when shopping when considering night vision or vision at dusk based on exit pupil.

As we know..... having a larger exit pupil on your binoculars "which usually means more weight and expense" is to no avail if your eyes can't enlarge that big anyway?

I hear when you are around 20 years old or so your  pupils can dilate up  to 7 - 8 mm, but when age 50.. only around 5.0mm.

The problem is "how do you know what yours are?

How can you measure?

If someone tries to measure them for you, they will need light to see which would in turn constrict them?

I don't know if an optomologist can tell based on the reaction to his eyedrops etc...

But I've always questioned folks who say "my eyes can dialate to 7mm etc".. how do you know that and who told you?


Anyone who can shed some light on this, I would appreciate your comments.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 09:45
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Generally speaking I have noticed that with 7x and a 50mm obj that is where the mag works to for me, beyond that and I start to see a difference, under that i see no difference so I'm assuming that 7 is what mine dialate to.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 17:28
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Any eye doctor can measure your eye pupils.  I even had mine go outside with me to measure in bright daylight.

This is all done "without" the use of drops.

 

 



Edited by Bird Watcher
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 17:34
windstrings View Drop Down
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Measuring in light is easy.... my point was how do you measure the maximum dilation in total darkness when it takes light for the measurer to see by .....which will cause the pupil to constrict from that light?

"Light to see by" will alter and skew the measurement of true maximum dilation.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 17:45
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No one experiences "total darkness" unless you are in a cave.

 

There is always natural light from stars.

 

The lowest light setting at the eye doctors is sufficient enough to give an accurate measurement. 



Edited by Bird Watcher
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2007 at 18:09
windstrings View Drop Down
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Your right, as total darkness would need IR equipment... I mean more like twilight.

I think drops would "muscle" the eye into dilating farther than twilight alone would do thus skewing the test too.

I think the easiest way would be to have several binocs on hand with varying exit pupils and keep switching as they go bigger in a twilight situation until you see no difference, then back up by one and thats your size!

Unfortunately, I don't know an easy way to do that because you would have to have the same quality of binocs to do the test.... even if you found or borrowed some with different exit pupils, the quality of glass would need to be the same or you would again skew the test.

This isn't a big deal... just a fun thing to know... but if we could figure an easy way to do this.. it could save someone big bucks and unnecessary weight from buying a binoc with a bigger exit pupil than that persons eye will go anyway. Or even allow them to go up a notch in magnification without breaking the limits of their vision.

I have my 10 X 50's.. I think I'm pretty close and if not.. I don't want the added weight from larger mm lenses anyway....

But if someone was night hunting for hogs etc....it would be valuable information for them to have for their purchase as some prefer magnification too as an aid for night vision, but as we know... going up in magnification complicates the issue of exit pupil as it makes it drop with a given mm of lens.


Edited by windstrings
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