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30mm and exit pupil question

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/03/2004 at 21:30
obi-wan View Drop Down
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Have some technical questions before a purchase.  1st how do you determine exit pupil and how much does that play into low light.  I read something that the eye maxes out at 7mm but when a scope lists it specs. it doesn't have one number but multiple   2nd I have heard 30 mm was good for low light scopes, but also the bigger the scope (i.e. 50mm)lets in more light, so that would be contradicting reports.  Thirdly, I am looking at a Burris FFII with the lrs ballisticplex primarly because of what I have read on this site and am curious other than the lit reticle and range marks will it be more clearer or a better scope than my Leupold m8-6x or would i need to step up to something like a bushnell elite 4200 or conquest ( which is quite a bit more) to make a difference.  Will be mounted on a 270 used primarly for deer hunting 300yds and less.  And Lastly is there something else I should be considering when choosing a scope.   If someone has a suggestion other than what is listed am all ears...



Edited by obi-wan
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2004 at 07:06
DAVE44 View Drop Down
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     I am no scope expert by any means and I am new to this stuff myself. I think I can answer your question though. The exit pupil is the diameter measurement of the circle of light that comes through and out of the eyepiece of the scope and onto your eye. They say that you eye can only dialate to about 7mm so that is the most light that your eye can let in. So any exit pupil of 7mm or more is what you wanyt for low light situations. Now to determine the exit pupil is quite simple. You simply divide the objective lens diameter by the power of magnification. For example a 4x32 scope would have an exit pupil of 8mm, 32 divided by 4. This means your are meeting and slightly exceeding that 7mm. If you are noticing several numbers listed for exit pupil that is because you are looking at a variable power scope which means that it will have several different exit pupil depending on what power of magnification you have it set for. Those numbers probably stand for the exit pupil at lowest power and exit pupil at highest power. Example on a 3x9x40 the lowest power is 3, so 40 divided by 3 is 13.3, the highest power is 9, so 40 divided by 9 is 4.4 therefore your exit pupil range on a 3-9x40 is 13.3-4.4. So during low light any power that allows 7mm OR MORE is what you want to set it at.

Edited by DAVE44
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2004 at 16:23
obi-wan View Drop Down
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Thanks for the help, now does anyone have any idea about if the burris would be a better scope than the exsisting leupold or about the same?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/08/2004 at 09:22
Chris Farris View Drop Down
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The Leupold M8 6x42 is a hard scope to top.  It uses the Multicoat 4 coatings, has less lenses than a variable and puts out a perfect 7mm exit pupil.  I think you would have to get into a Bushnell Elite 4200 to top it.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/08/2004 at 18:33
SAKO75 View Drop Down
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I read this everywhere and people really thin 1 extra lens is going  to make or break a shot on an animal regarding light transmission?
I emailed S&B and asked them point blank if a fixed scope is "brighter" than a variable due to less lenses and they said while it might "measure" very small fraction of a percentage brighter, with quality glass and coatings, 1 extra lens will not degrade the light transmission enough for the human eye to tell the difference.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/15/2004 at 17:36
Chris Farris View Drop Down
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I don't think anyone really believes one extra lens is going to make or break a shot.

 

A fact is a fact and if we want to start debating how relevant facts are when it comes to optics, glass, coatings, construction, etc. then we will be relying mostly on speculation.

 

With that train of thought you could say there is no need for a scope with fully multicoated lenses when just multicoated will do.

 

BTW, who did you talk to at S&B.  Was it S&B in Germany or New England Arms (U.S. Importer).

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