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Exit Pupil and Brightness Question...

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 07:59
matthewdanger View Drop Down
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Lets say, for example, that you have 6x30 bins and a 8x40 bins. Both have the same quality of glass, both have the same quality of coatings, both have a 5mm exit pupil, and all factors other than magnification and objective size are equal.

Will the 8x40 be brighter because of the greater surface area of the objective or, all things being equal, will the exit pupil dictate that both scopes are equally bright?

Thanks!
Matt
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 08:33
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Originally posted by matthewdanger matthewdanger wrote:

will the exit pupil dictate that both scopes are equally bright?
Yes.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 08:41
matthewdanger View Drop Down
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Originally posted by lucznik lucznik wrote:

Originally posted by matthewdanger matthewdanger wrote:

will the exit pupil dictate that both scopes are equally bright?
Yes.
 
Thank you lucznik!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 09:39
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I may be mistaken, but the 8x might have a bit better twilight performance due to extra magnification. This helps make out details even in low light. Someone help me out. Am I on the right track?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 09:46
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Good point image brightness is the same but you are closer with the 8X so would have extra detail.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 10:11
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yes, trigger is correct. That is the whole theory behind "Twilight Factor" or Twilight Performance Factor.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 10:13
matthewdanger View Drop Down
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So they will be equl in brightness, but greater detail will detecable with the 8x? That makes sense.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 10:13
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All else being equal, a larger objective will deliver more detail to the eyes than a smaller objective lens regardless of the magnification of the binocular.
 
 
**A smaller objective diameter affects how much detail we can see. A bigger lens has a larger central area (sweet spot) of resolution than the smaller lens. Bigger lenses have more surface area, allowing additional light to end up in the right place, so we see more clearly.
(**Borrowed from Nikon, The Complete Optics Guide for Successful Hunting).
 


Edited by Bird Watcher - March/05/2009 at 11:10
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 10:15
Roy Finn View Drop Down
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Don't confuse the poor guy.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 10:31
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I'm not confused yet! I'm taking it all in. This is good stuff.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 11:16
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Matthew,
 
Pick up a copy of How To Choose Binoculars by Alan R. Hale. CLICK HERE
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 11:18
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This is where the difference in lens quality, coatings, internal baffling comes into play.  A big lens delivering lots of brightness but a poorly resolved image is not a good trade off for a smaller but better quality lens.
 
Think Conquest 3-9x40 versus BSA 3-9x50
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/05/2009 at 11:26
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Originally posted by matthewdanger matthewdanger wrote:

 Both have the SAME QUALITY of glass, both have the SAME QUALITY of coatings, both have a 5mm exit pupil, and ALL FACTORS other than magnification and objective size ARE EQUAL.

ALL THINGS BEING EQUAL

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