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Exit Pupil and Brightness Question... |
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matthewdanger
Optics GrassHopper Joined: March/02/2009 Status: Offline Points: 19 |
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Posted: March/05/2009 at 07:59 |
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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
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lucznik
Optics Master Joined: November/27/2004 Location: United States Status: Offline Points: 1436 |
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What if the hokey pokey really is what it's all about?
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matthewdanger
Optics GrassHopper Joined: March/02/2009 Status: Offline Points: 19 |
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Thank you lucznik!
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trigger29
Optics Master Extraordinaire X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ? Joined: September/29/2007 Location: South Dakota Status: Offline Points: 4353 |
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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?
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"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." |
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Dogger
Optics Jedi Master Joined: January/02/2007 Location: Ontario, Canada Status: Online Points: 8914 |
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Good point image brightness is the same but you are closer with the 8X so would have extra detail.
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God save the Empire!
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Roy Finn
MODERATOR Steiner Junkie Joined: April/05/2004 Location: United States Status: Offline Points: 4856 |
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yes, trigger is correct. That is the whole theory behind "Twilight Factor" or Twilight Performance Factor.
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matthewdanger
Optics GrassHopper Joined: March/02/2009 Status: Offline Points: 19 |
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So they will be equl in brightness, but greater detail will detecable with the 8x? That makes sense.
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Bird Watcher
Optics Master Joined: August/30/2006 Status: Offline Points: 1523 |
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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 |
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Roy Finn
MODERATOR Steiner Junkie Joined: April/05/2004 Location: United States Status: Offline Points: 4856 |
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Don't confuse the poor guy.
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matthewdanger
Optics GrassHopper Joined: March/02/2009 Status: Offline Points: 19 |
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I'm not confused yet! I'm taking it all in. This is good stuff.
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Bird Watcher
Optics Master Joined: August/30/2006 Status: Offline Points: 1523 |
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Matthew,
Pick up a copy of How To Choose Binoculars by Alan R. Hale. CLICK HERE
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Dogger
Optics Jedi Master Joined: January/02/2007 Location: Ontario, Canada Status: Online Points: 8914 |
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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
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God save the Empire!
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Bird Watcher
Optics Master Joined: August/30/2006 Status: Offline Points: 1523 |
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