# Scope 32mm vs 40mm vs 50mm



## flyingfrog509

All things being the same, would a 3-9x32mm or a 3-9x40mm scope be more bright or have better resolution?

I personally don't like the 50mm lenses simply because I can't get good cheek weld.  So I'm kind of looking at the differences between the Burris Timberline 4.5-14x32 and the Burris Fairfield II 4.5-14x42.  I just can't seem to find a store that has both in stock to compare.

Thoughts?


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## Hankus

Theoretically bigger the objective the more light gathered, so the 40 will transmit more light throught the scope at low light conditons. That is what makes it "brighter".


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## Dub

It depends on what magnification you are set at in low light.

The larger objective will allow you to zoom in a bit more and still flood your eye with the same image quality.

40mm is probably all I ever need but I overkill with 50mm for some dumb reason.

I've come to fully believe that the glass quality makes more difference overall.  I'd take a higher quality 40mm over an average 50mm any day.

I'd especially make this move if the 40mm was better aligned to my eye




Good luck!


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## olchevy

I use a 1-4x24 and it lets in plenty of light for low light hunting...

Obj size will make a small difference. however the biggest difference comes in play with the magnification and quality of lenses and coatings.......
With the 1-4x24 I can see the reticule easily at night if the moon is out, And its a pretty fine reticule too.... Illumination helps a lot too, but you want to see how low it can go not how high, mine goes from 1-11 with also a NVG setting....in low light I have never turned it above 3, it usually stays on 1 or 2....

The reticule is the one in my avatar The center dot is a very fine 1 moa dot...

I do not recommend one that illuminates the whole reticule, because a a lot of times it will overload your image with light..


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## MoonPie

never use anything on my deer rifle other than a leu 50.  Can't say to any other, but that said.... have never even considered another.


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## olchevy

MoonPie said:


> never use anything on my deer rifle other than a leu 50.  Can't say to any other, but that said.... have never even considered another.



If it works for you then that is all it matters! whether it be a cheap 20$ tasco or some 3,000$ Schmidt&Bender scope.....


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## miles58

I have a Burris Fullfield II in 4.5-14 I like it a lot.I also have a Zeiss 4.5-14 which is better, but not so much as to say you have to spend Zeiss money to get a decent scope.  The difference between a 32 and 44 mm objective with good optics won't make a difference to legal hunting.  If you need to step up to the top level of performance in optics, that gets into a lot more money

Dave


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## chuckdog

Quality over Quanity. As Dub stated. I'd rather spend the same money for a quality 38~40mm over the 50mm. This holds especially true as the price range lowers. It's about marketing, Bigger has to be better, right? Not to mention what it does to the looks of an otherwise beautiful rifle. Nothing looks more ridiculous to me than a huge 50mm+ scope sitting atop a good looking lightweight or compact rifle. To each his own though. We all see the world through different eyes. if I'm selling scopes, I'm going to market what sells. Chuckdog.


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## bullgator

All things being equal, the 40mm will allow more light. But!, all things aren't equal between the Timberline and Fullfield models with the Fullfield being a higher end scope. I'd go with the Fullfield every time.


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## BamaBart

If you can get a 50mm get it.


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## Dead Eye Eddy

It's a personal preference thing.  I think that a 40mm scope is the best all around scope.  That said, with the exception of my handgun scope and shotgun scope, I don't even own a scope with an objective smaller than 44mm.  I like big scopes that give me a huge field of view and plenty of light.  All three of my main deer rifles, not counting my truck gun, have Leupold Vari-X III 50mm's on them.


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## Apex Predator

I read somewhere that 44mm was the largest usable objective, as far as light gathering was concerned.  In other words, a 50mm is a waste of money.


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## Dead Eye Eddy

The way I understand light gathering ability is this.  Your eye's maximum pupil diameter is 7mm.  A scope's exit pupil is equal to the objective diameter divided by the magnification.  Any exit pupil over 7mm is wasted light.  A 32 mm scope gives a 7mm exit pupil at about 4.5X.  A 40mm scope gives a 7mm exit pupil just short of 6X.  A 50mm scope gives a 7mm exit pupil just past 7X.  In other words, you can the best possible light gathering ability at higher magnifications with larger objectives.


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## treemanjohn

Scopes do not gather light, they transmit light. Glass quality is the greatest factor in light transmission. Also there is only so much light that can go through a 1" tube. I personally believe that a 40 -44 mm is spot on for a 1 " tube.


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## deadend

I equate 50mm scopes with wheel spinners, diesel stacks,loud mufflers, and large spoilers.  They may seem cool at first but the new wears off when you gotta deal with the reality of the object.


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## flyingfrog509

olchevy, what kind of scope & reticle is that you have pictured...I've never seen anything like it. (not that I've seen much)


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## Larry Rooks

On short range guns, or guns I use in the thick stuff, I go with a 32 MM, all I need for those 20-75 yard shots, gathers plenty of light and extrmely clear.  On long range guns I use the 40-42 MM and no more.  I do not like scopes sitting too high and that usually happens with a 50 Mm scope.  I know Leupold solved the problem with the new
design, but why pay several hundred dollars for one when what I got works fine (Kahles 32 and 42 MM scopes, plus
an older Leupold or two


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## olchevy

flyingfrog509 said:


> olchevy, what kind of scope & reticle is that you have pictured...I've never seen anything like it. (not that I've seen much)



It is used in a LeatherWood Hi-Lux CMR(Close medium range) 1-4x24....it runs a 30mm tube

It is has predetermined aiming points for out to 900m for .308. The turrets actually lock down via two allen screws so once you sight is set it will stay there. That center dot is a very fine 1 moa dot which I like a lot, and on 1x you can shoot both eyes open just like a red dot it has 11 settings for the illuminated reticule although in evening I have never turned it above three, and it also has a NVG setting to for if you run well NVG......

The only thing that takes some getting used to, is that fact that you range your targets by width not height. Other than that it is a great scope.

I will say that I have only got to use this scope out to 200m so far so I have not been able to test and see how close the marks are to where I actually hit....I am working on expanding our 200m range at home to 400m I just haven't had the time....And I do not know of anywhere I can go further than 400m around where I live.


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## germag

treemanjohn said:


> Scopes do not gather light, they transmit light. Glass quality is the greatest factor in light transmission. Also there is only so much light that can go through a 1" tube. I personally believe that a 40 -44 mm is spot on for a 1 " tube.



The diameter of the tube has nothing to do with light transmission capabilities. A 30mm tube does not improve light transmission....nor does a 35mm tube. 

The only practical benefits from a bigger tube is that you can have a bigger erector...more room for internal adjustment....and it makes for a stiffer scope.


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## NOYDB

I agree with Olchevy about the lighted reticle. I've tried the ones that light the whole reticle and it will blind you in low light conditions if you have it turned up too high. It can wash out the target.

The illuminated center dot on the other hand, for me, makes it easier to aim quickly. Sorta like a laser pointer, it says "touch you there".

As to scope size, I have a bunch of different sizes matched to the gun, caliber and intended use. I have chubby cheeks and can get a good weld with a 50mm scope on some guns that an underfed fellow might not be able to achieve. 

Instead of trying for one size fits all. Try matching the gun and scope configuration to you specifically. Experiment. Don't forget you can add cheek pieces to the stock, There are extention rings that allow you more forward/backward movement in scope position. On most popular guns you can swap out the stock. You can change butt pads to get more or less length of pull. 

If you are lucky enough to be "factory" sized, enjoy. But otherwise you might be surprized at how doing a little modification can make a gun so much more fun to shoot. Notice how competition shooters almost never shoot "factory" guns (unless they are paid to).


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## treemanjohn

germag said:


> The diameter of the tube has nothing to do with light transmission capabilities.


It absolutely does. Take 3 pieces of pipe all with the same length 1/2, 3/4, and 1". Then you'll see what allows more light through. The larger the diameter more light. 

Scopes don't have an amplifier on them


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## Predator56

i think the best all around scope less than 1000 is the zeiss conquest 3-9x40 with #4 reticle

bright enough to do way past legal and bold enough retiocle ot make the shot


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## Jetjockey

treemanjohn said:


> It absolutely does. Take 3 pieces of pipe all with the same length 1/2, 3/4, and 1". Then you'll see what allows more light through. The larger the diameter more light.
> 
> Scopes don't have an amplifier on them



No it doesn't.  Germag is 100% correct.  If 300mm scopes transmitted more light then you would see them on every hunting scope there is.  The only reason for 30mm scopes is for the added range of adjustments.  Thats why nearly every tactical scope is 30mm while huning scopes are 1 inch.  Like others have said, the quality of glass has a lot more to do with low light capability then the objective size.  If you want better low light capability, then spend the money on a better scope.  VX3's, Conquests, Minox, and others mid to upper end scopes will give you all the low light ability you need in a 40mm scope.  The cheap scopes won't make up low light ability from cheap optics with a 50mm objective.


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## fishtail

Dead Eye Eddy said:


> The way I understand light gathering ability is this.  Your eye's maximum pupil diameter is 7mm.  A scope's exit pupil is equal to the objective diameter divided by the magnification.  Any exit pupil over 7mm is wasted light.  A 32 mm scope gives a 7mm exit pupil at about 4.5X.  A 40mm scope gives a 7mm exit pupil just short of 6X.  A 50mm scope gives a 7mm exit pupil just past 7X.  In other words, you can the best possible light gathering ability at higher magnifications with larger objectives.



Dead Eye Eddy hit on one of the main points to be considered.
7mm is the normal maximum dilation of the human pupil in total darkness. The normal dilation at near darkness (normal hunting dark 30) is near 5mm.
Many scopes have varied brightness qualities as to lens quality, you get what you pay for.
Back to the posted question.  
3x9x32 on 6x is about as matched as you can get to optimum perceived light gathering, as to what YOU are capable of.
Same goes for a 2.5x10x40 at 8x or a 4x16x50 at 10x.
The numbers above have been well published well over 40 years ago and are in many of today's best optics manufacturers brochures, if you look at them.


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## bteate

fishtail said:


> Dead Eye Eddy hit on one of the main points to be considered.
> 7mm is the normal maximum dilation of the human pupil in total darkness. The normal dilation at near darkness (normal hunting dark 30) is near 5mm.
> Many scopes have varied brightness qualities as to lens quality, you get what you pay for.
> Back to the posted question.
> 3x9x32 on 6x is about as matched as you can get to optimum perceived light gathering, as to what YOU are capable of.
> Same goes for a 2.5x10x40 at 8x or a 4x16x50 at 10x.
> The numbers above have been well published well over 40 years ago and are in many of today's best optics manufacturers brochures, if you look at them.



absolutely! Great explanation, Dead Eye and fishtail.


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## treemanjohn

Jetjockey said:


> No it doesn't.



Yes it does. It's the same as the aperture on a camera or the pupil in your eye. The larger the aperture of a camera the more light that's allowed to enter the camera sensor. Same thing holds true with pipe. The larger the pipe the more amount of flow. Telescopes with a larger diameter collect exponentially more light and resolution

http://en.wikipedia.org/wiki/Optical_telescope


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## NOYDB

It's more complicated than just objective size or tube diameter. You also have to consider the number of lens elements. Shape of the lenses, the type, number and placement of the coatings. The type of glass used. Etc.

In Europe where they can hunt legally at night they use 60-70-80mm objective scopes. They adjust their stock cheek pieces to match.

Tube size does not determine light transmission because the light is not going in a straight line. The lenses focus the light gathered from the surface of the objective lens into smaller areas that are then transmited and additionally focused by the rest of the lenses thru the rest of the scope. That's why your exit diameter isn't 40mm.

The apeture on a film camera is adjustable to change the amount of light allowed in to expose the film. Film exposure is also a function of time. For any given light level you can open the apeture wider or leave it open longer depending on the type of film used and results desired. Large telephoto lenses are used to transmit more light and magnify the image, but have trade offs in shutter speed and film types used. 

The larger the lens, the harder it is to grind it to shape to prevent distortion. The more lens elements you have the harder it is to get them all working together. What you are supposed to be paying for with top quality/price scopes is the precision and robustness of their assembly of all the parts to limit errors. The best glass in the world, misaligned, will make a Wallyworld Tasco look good.

All that is fun to cuss and discuss, but bottom line, is get the configuration that works for you on your gun. Worry less about what everyone else has and more about what YOU need.

Or what you WANT. You want to put a 80mm 20-60 power spotting scope on your Cricket, go for it.


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## NOYDB

To the OP. All else being equal, a 40mm scope will transmit a viewable image at lower light levels than a 32mm will. The difference probably won't matter during legal shooting hours.


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## Jimmyp

flyingfrog509 said:


> All things being the same, would a 3-9x32mm or a 3-9x40mm scope be more bright or have better resolution?
> 
> I personally don't like the 50mm lenses simply because I can't get good cheek weld.  So I'm kind of looking at the differences between the Burris Timberline 4.5-14x32 and the Burris Fairfield II 4.5-14x42.  I just can't seem to find a store that has both in stock to compare.
> 
> Thoughts?



What type of rifle is it going on?  Why do you need a 4.5 x 14?  People out west shoot deer at 500 yards with simple 4 and 6x scopes.  Put your money into quality over quantity.  I used to hunt with a fellow that had a 6-18 bushnell banner on his rifle.  To my eyes it looked like peering thru a coke bottle, he loved it but was near blind anyway.  I saw a show where a big name professional hunter jumped a deer up while walking carrying a rifle with a "big" scope on it and promptly gut shot the deer, not saying it was the scopes fault but it couldn't have helped.  If your hunting varments thats one thing, deer thats another. 

A decent 3 x 9 like the Zeiss Conquest or the new Minox 3 x 9 with a 42 mm objective is all you will ever need for deer.  I hunt with 2.5 x 8's x 32's but Zeiss does not make that model anymore.  Again the optics and the quality of the coatings on the lenses. If you sit to last legal shooting time you can still see the reticule and the deer out to 50 yards or so with good optics in a 32 mm objective.  I know this because I do it all the time.


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## Jetjockey

treemanjohn said:


> Yes it does. It's the same as the aperture on a camera or the pupil in your eye. The larger the aperture of a camera the more light that's allowed to enter the camera sensor. Same thing holds true with pipe. The larger the pipe the more amount of flow. Telescopes with a larger diameter collect exponentially more light and resolution
> 
> http://en.wikipedia.org/wiki/Optical_telescope



You better tell the people at Leupold the were wrong when they told me that the tube size made no difference in low light gathering ability.  This question had been brought up on other forums, so I called Leupy directly when I was looking at buying a scope.


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## treemanjohn

This is my original quote. It doesn't mention anything about a comparison between a 1" and 30mm scope. I said there's only so much unaided that can go through a tube of ANY size. 





treemanjohn said:


> Scopes do not gather light, they transmit light. Glass quality is the greatest factor in light transmission. Also there is only so much light that can go through a 1" tube. I personally believe that a 40 -44 mm is spot on for a 1 " tube.



The pupil of your eye enlarges to allow more light. The aperture of a camera enlarges to allow more light as stated before

Now if you want to compare a 30mm TUBE (not scope) to a 1" TUBE (not scope) if all things are equal a 30 mm TUBE will allow more light than a 1" TUBE because the 30mm TUBE is 4.5mm larger. Bigger hole more light, it's pretty simple


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## Jetjockey

Well, its not that simple.  Your right, a 30mm will allow more light then a 1 inch tube.  But were not talking tubes, were talking scopes.  But Im not going to argue with you about it.  The folks at Leupold made it pretty clear to me that 1 inch scope vs 30MM scope has no difference in light gathering, or transmission.  If you don't believe me, call Leupy and talk to Trent.  There is absolutely no difference in a 30mm scope vs a 1 inch scope in regards to light gathering/transmission.


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## NOYDB

Light travels in a straight line. It is refracted, bent, when it passes thru the boundary between different substances. Air/water, air/glass, air/coating/glass/coating/gas in tube/more coatings and glass/air/your cornea etc. It also changes transmission speed in each substance it passes thru (not enough for you to notice, but it does).

That bending plus the curve of the lens is how a lens focuses and magnifies. It's why your objective bell is bigger than the tube and why your eye piece is also bigger. Optics makers rely on centuries of experience and lots of math to attempt to control the light striking the surface of the objective and make it go where they want. The tube can be ten times the size and it won't pass any more light than is allowed to enter the system by the surface area of the objective. Think of burning ants with a magnifying glass. Your glass may be 3-4 inches across but the focal point is hardly bigger than the ant.

The larger the surface area of the objective the more light they have to work with trying to get it into your eye.  A 50mm objective will pass more light into the system than a 32mm objective will. 

After a certain point, the limiting factor is your eye, and then it doesn't matter how much "bigger or better" the scope is. Look towards the rising or setting sun, even if it's below the horizon, and you just threw away all the money you spent on your glass. Even more so as you get older. A larger objective isn't going to compensate for not having your back to the sun.

On a camera, the aperture is used to control depth of field. Shutter speed is used to control exposure.


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## olchevy

Jetjockey said:


> Well, its not that simple.  Your right, a 30mm will allow more light then a 1 inch tube.  But were not talking tubes, were talking scopes.  But Im not going to argue with you about it.  The folks at Leupold made it pretty clear to me that 1 inch scope vs 30MM scope has no difference in light gathering, or transmission.  If you don't believe me, call Leupy and talk to Trent.  There is absolutely no difference in a 30mm scope vs a 1 inch scope in regards to light gathering/transmission.




I believe the people at Leupold did not mean there is no difference, but instead the difference is Negligible to most users, there will be a difference but possibly not enough for our eyes to notice..


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## Jetjockey

Maybe, but when I asked him if there was ANY difference he said no.  I then said "so the only difference between a 30mm and  a 1 inch scope is the ability for higher adjustments in the 30mm?".  His response was "that is correct, there is no difference in low light capability between a 1 inch and 30mm scope, thats why our hunting scopes are 1 inch and our tactical scopes are 30mm."  He then told me the same thing as the guys above stated.  The eye can only handle and exit pupel of 7mm, and the tube size has nothing to do with it.  He said a 50mm scope will allow slightly higher light transmission, but not enough to make a difference 99% of the time.


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## 01Foreman400

If all the glass is equal the bigger objective will transmit more light.


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## olchevy

on the guy who above was talking about on telescopes, you are right but have the wrong Idea... I do A LOT in astrological observations at College...

YES, the larger the more light and clearer images, however in astronomy we are taking huge jumps in size from little 4'' telescopes up to some bigger 3 and 4 foot Dobsonians.....Yes their is a huge difference in every aspect of the quality.

But in this instance we are talking about a tiny 4.6mm difference...basically a tenth of an inch....This a minute and rarely noticeable difference


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## Predator56

01Foreman400 said:


> If all the glass is equal the bigger objective will transmit more light.


a higher exit pupil so in that sense more light but it doesnt mean you will see a deer wit h56mm that you wont with a 42mm.

If I have a scope set on 6x with a 42mm and yours is on 8x with a 56mm we both are delivering 7mm of light to the pupil. If your 56mm is on 12 and my 42mm is on 4x then the little objective is delivering more light...

bigger objectives only make a difference on higher powers

if you like to shoot deer on high power this might be important


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## NOYDB

Actually, the size of the exit pupil is not the amount of light being delivered. It's the size of the area that the image is being focused to. In a prefectly dark room the exit pupil is still the same, just nothing being transmitted.

A 1 mm exit pupil can still transmit enough light to blind you if the source is bright enough.


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## Predator56

NOYDB said:


> Actually, the size of the exit pupil is not the amount of light being delivered. It's the size of the area that the image is being focused to. In a prefectly dark room the exit pupil is still the same, just nothing being transmitted.
> 
> A 1 mm exit pupil can still transmit enough light to blind you if the source is bright enough.


yes this is true but we are not talking about hooking up a 300 watt xenon light source and looking into it. we are talking about dusk/dark conditions. I have owned all the zeiss, swaro, schmidt&Benders, etc... I now own a conquest because No matter which way I sliced it, i couldnt justify the addtional 1000$... i do agree that obj size does help but usually its because you can turn the magnification up higher


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## 01Foreman400

Predator56 said:


> i do agree that obj size does help but usually its because you can turn the magnification up higher



Bingo!


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## WTM45

Exactly.
If one desires a 50mm, and can fit it correctly on the rifle of their choice, then by all means go for it.
It's not that difficult to do.

Quality glass should be the first consideration.  Size and magnification second.  One buys what they are able to or willing to invest in.


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