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50mm VS 56mm on 8x fixed scope

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 15:11
cr500 View Drop Down
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I,m looking for a premium quality 8x fixed scope for night shooting and have been looking at various 8x56 scopes. As our pupils only go to 6mm or so as we go past 40 yrs old, is there any actual advantage to the 7mm exit pupil of 56mm scopes VS 6.25mm of 50mm scopes? Has anyone (not counting teensagers with perfect eyes) actualy tested similar quality scopes in 50mm and 56mm to see if there is any actual nighttime advantage. I want the brightest scope possible, but didnt want to go for the extra size of the 56mm if it is no advantage to older (40+) eys.
I,m talking about a Zeiss, S&B, Swaro or Docter.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 15:58
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Have a doctor check your eyes for dialation, or use a variable that can achieve the exit pupil at 5,6,and 7 likely the best you'll notice is gonna be 5, or 6 so the 56 probably won't benefit you at all, the 50 should do you as well as the 56.
Best of luck sir, Welcome to the OT.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 16:00
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cr500, it is not only the size of the exit pupil that matters.  I have seen this discussed before, as if the size of the human pupil is a limiting factor.  It is to a certain degree and progressively becomes so the smaller it gets.  In addition, it becomes more complicated, as the pupil is not static, it is reactive, i.e. as light enters, the more there is, the pupil contracts.  You also have stray light entering the eye that can cause it to contract.  But, with all things being equal, the more light that a scope can bring to your eye and remember this is at a level that is not going to make your pupil contract to a pinpoint, with reference to the differences in the scopes, the brighter the scope will be.  So, two scopes, identical in every way, except that one has a 50mm objective and the other 56mm, the later will be brighter.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 17:03
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Originally posted by Dolphin Dolphin wrote:

cr500, it is not only the size of the exit pupil that matters.  I have seen this discussed before, as if the size of the human pupil is a limiting factor.  It is to a certain degree and progressively becomes so the smaller it gets.  In addition, it becomes more complicated, as the pupil is not static, it is reactive, i.e. as light enters, the more there is, the pupil contracts.  You also have stray light entering the eye that can cause it to contract.  But, with all things being equal, the more light that a scope can bring to your eye and remember this is at a level that is not going to make your pupil contract to a pinpoint, with reference to the differences in the scopes, the brighter the scope will be.  So, two scopes, identical in every way, except that one has a 50mm objective and the other 56mm, the later will be brighter.
 
 I 've always been a bit suspicious of that whole premise. It always seemed to me that there had to be more factors at work there than the exit/ eye pupil relationship.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 17:33
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On my German scopes, I have both 8x50 and 8x56. I can honestly say there is a slight difference that you can tell. Of course that extra few minutes is what you pay for.
Derek
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2008 at 18:38
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Ronk has a point, it is not only Dia, but focal lenght and some other related stuff that comes into play. 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/19/2008 at 21:55
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The reason I ask is that Swarovski is one of the scopes I was looking at. They have 8x scope in either 50mm or 56mm. So same maker, it seems from what you are saying that 56 will still be brighter all alse being equal?
I know I have a cheap 8x56 which is not as bright as my top shelf variables with 50mm lenses, so I know there is more too it than just objective size and fixed scope having less lenses.
So for the flat out brightest night scope possible, 56mm will still be slightly brighter than 50mm with my eyes, is that right?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/20/2008 at 13:59
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Yes, with all other things being completely equal with the same brand of scope.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/20/2008 at 14:09
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The human eye is very complex and all of the above is a simplification, but in general true.  You add age to the formula and things get more complicated.  Take a cataract for example.  Light and the intensity thereof can make a difference in whether brighter is better or not, depending on the cataract makeup, structure, density, location and density.  In some cases, more light may be a hindrance.  Other age related and non-age related eye problems can also affect how a person perceive the image seen through a scope.  Sometimes I think that is why we see some wide variations in people's opinions in what are known as premium scopes.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/20/2008 at 14:29
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Overall my eyes are in good condition and I seem to have slightly better than average eyesight (probably not as good as they were when I was 18). Hopefully the 56mm lense will help me as that is what I will go for. I now only go for premium scopes as I am replacing all of my cheaper scopes with good ones. This next 56mm scope will be the last one to complete the replacement program. I have a draw full of cheap scopes now, which I am giving away to new shooters who do what I did at first, that i look through a cheap scope at a gun shop in broad daylight and say, "jeeze this cheap scope is nearly as clear as that expensive scope.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/21/2008 at 01:39
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jeeze this cheap scope is nearly as clear as that expensive scope.
Cr500, that is a good line!!!
I read an article the other day that suggested if the glass and the coatings are good, that the human eye will not benefit much by small increases in larger objectives. He was making a case for "should I spend more money on good glass and coatings, or rather more money on a bigger objective". So if you are buying the same glass and coatings, the next step to maximising light is a bigger objective. If you were planning to buy a lesser grade glass and coatings to make up for the larger objective, then rather go for the smaller objective and better glass.
Of course now you have to decide if the extra weight and bulk is worth the extra light! No free ride brother!


Edited by 8shots - January/21/2008 at 01:59
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/21/2008 at 04:07
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8Shots. I,m sure all newbies said the same things about cheap scopes looking nearly as good as expensive scopes, when viewed outside a shop window at high noon.  I bought a cheap 8x56 years ago, thinking it will be the best nightscope around, but after comparing it to my top quality variables with 40 and 50mm rings, it doesnt come close.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/22/2008 at 11:17
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if you must have fixed -
 
get a 7x56 meostar by meopta and it will be as bright (because of larger exit pupil) than those others and save you a ton of money. my 2 cents.
 
or the 6x42 zeiss victory would be great and allow for more versatility.
 
if you are stuck on 8x56 - i vote zeiss.
 
J
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