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40mm objective vs 50mm.

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 00:15
slowr1der View Drop Down
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So I understand that a 50mm objective will let more light in at the higher powers than a 40mm one. My question is at 3-6x will the 50mm let a noticeable amount more light in? I'm trying to decide if the 3.5-10x50 Burris FFII is worth the extra over the 3-9x40 for hunting in low light. I often read guys online talking like the 50mm is a waste of money, but when I talk to my friends in person that have scopes with a 50mm objective they all say it's all they will ever buy and that they love them.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 00:52
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The 50mm will be brighter in low light due to its larger exit pupil.  I prefer riflescopes with smaller objectives to facilitate a low mount and proper cheek weld.  If you are hunting at night, or trying to squeeze the very last minutes out of the dawn/dusk, the 50mm might be for you.  But under daylight conditions, there will be very little difference.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 06:23
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Originally posted by Bitterroot Bulls Bitterroot Bulls wrote:

The 50mm will be brighter in low light due to its larger exit pupil.  I prefer riflescopes with smaller objectives to facilitate a low mount and proper cheek weld.  If you are hunting at night, or trying to squeeze the very last minutes out of the dawn/dusk, the 50mm might be for you.  But under daylight conditions, there will be very little difference.
 
I agree, but would like to add that some 40 or 42mm scopes will outperform their 50mm counterparts in lowlight situations just due to superior glass, coatings, workmanship, etc.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 12:25
robbie View Drop Down
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Originally posted by slowr1der slowr1der wrote:

but when I talk to my friends in person that have scopes with a 50mm objective they all say it's all they will ever buy and that they love them.
No doubt they love them, but what if anything are they comparing to?
 
My son has an acceptable starter bino (Vortex Crossfire) that he LOVES.  The other day we were looking out the window at something and he was bragging how perfectly his were performing.  Then I let him look through me Fujinon CDs and he immediately said "wow - I want those."
 
I bet you friends would love looking through a comparable 40 also.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 12:37
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At 3 to 6 power there will be no noticable difference between light.  I think where you would see little if any gain would be at 9.  Divide the 40mm by 9 to get an exit pupil of 4.4.  On the 50, that changes to 5.5 so in theory if your eyes allowed it, might appear brighter on that setting (or maybe 8 power as well)
 
Also, 50mm a bit bulkier.  If you were using mostly 3-6 power I would get the 40mm.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2011 at 15:32
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To further expand on what JLud mentioned, about the maximum exit pupil usable by the human eye is 7...and that's for a healthy person in their 20s. The older you get the less you will be able to use. A 40 mm objective would still give you 6.67 mm @ 6X. But as mentioned would not be as good @ 9X. Two of the advantages of a scope with a smaller objective, however, is that usually they are shorter and can be mounted a little lower.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/10/2011 at 08:07
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I'd like to echo what JLud stated "in theory" this is a mathematical equation that determines the exit pupil of a particular scope or binocular, HOWEVER it does not factor in glass, coatings, etc.
 
Please remember this when making your decision.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/10/2011 at 16:13
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the human pupil can dialate to about 7mm. 

on 3x your fine. no loss of light transmission between lens objectives.

so if your on 4x, your eye will see just as bright of a picture on a 35mm or 36mm as it would on a 40mm, 50mm lens (assuming glass coatings and craftsmanship are equal in quality)

if your on 5x, your eye will see an exit pupil of 7mm on 35mm lens, 7mm+ on 36mm lens, 8mm on 40mm lens, 10mm on 50mm lens. remember your eye wont dialate more than 7mm for the average person, once again assuming glass coatings and craftsmanship are equal in quality

if your on 6x, your eye will see 6mm on 36mm glass, 8mm on 40 glass, 9mm on 50mm glass. now remember that once your pupils get to 7mm (if you have good eyesight) your eye will only process 7mm...can you manage with 1mm less of exit pupil or is exit pupil that important? if you have good eyesight, i wouldnt freak over it, if you have bad eye sight i would take that extra 1mm into consideration (i know it was 6mm ep vs 8mmep, but bc of your pupil i did 6mm vs 7mm ep.

so whats more important to you, weight of the scope or 1mm of exit pupil? if you walk in the woods a lot a 50mm is a pain in the dick. it catches everything. atleast in thick woods. it gets cumbersome. i never owned a 50mm lens because its just not for me. even at night. ill give it a try, but dont see a need. especially with how much of a sh*tty cheekweld id get on an ar15.

thats another thing, what kind of rifle is it going on? 2 of my friends who hunt at night hate 50mm scopes because prone position on a 50mm scope they have to raise their head up high. i had a conversation with one guy about sopes last week and he said how he loves his 50mm bc he can move his head a tiny bit and not have to worry about the scope turning black. 

keep in mind that larger glass maybe more comfortable your eye may be finding the target at night. l on the other hand, prefer 

if you hunt at night check out elusive wildlife. they make lights that attach to rifle scopes just like the nd3 laser but is half the price and i can vouch it works. out of every scope i look at, minox, zeiss, even thought about saving up for a swaro, a leupold vx3 2.5-8x36 is what i keep going back to. if you hunt at night, id check out bushnell elite 6500 or 4200. everytime i go out at night, its always more damp, any moisture in the air and let the fogging up begin. 

over on predator masters forum the going scope for night hunters seem to be the elite 4200. 

im not talking to you like your stupid, im sure you can do the math, but the exact thing i typed out above is what i go to for reference when i look to buy a scope. 

i hope i was able to help in some way.

supertool got me to stop hating on 50mm, but im not fully converted yet.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/10/2011 at 16:16
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i really need to start reading what others respond instead of scanning bc i just wrote the same thing all you guys did only 10x longerWhacko< ="-" ="text/;=UTF-8">Loco< ="-" ="text/;=UTF-8">Whacko
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/11/2011 at 05:37
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Guys, dont get hung up over the blasting exit pupil, it is as many have said, a mahtematical equation and tells nothing about scope quality.
 
What counts when low light is an issue (be it dusk, dawn or dense dark forest), is the quality of glass, coatings, the mechanical construction, color retention, contrast, waterproof/fogproof and the right reticle for said hunting.
A 1,5-6x42 of good quality, can be a much better alternative than a cheap 3-12x56.
 
As a rule I would say that the 3,5-10x50 wins, but again it depends most of all on the lense quality.
 
 
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