Home Forums Hunting & Shooting Hunting Optics 40mm vs 50mm scopes

Between a 40 and 50mm scope, which do you think would be a better hunting scope?

I like the smaller glass for a lower mount, and I like the looks better. At the moment, my hunting rifle is wearing a 1.5-5x20mm scope. I've got 40mm and 50mm on others.

It is a pretty subjective choice.

I've had all three (Leupie VXIII's) out at dusk for a side-by-side comparison in fading light, and couldn't tell much difference between them.

MM

Once you get an exit pupil of 5mm or over the scope is transmitting (based on exit pupil) all of the light the average human eye can use. In quality optics a larger objective can lead to a sharper, clearer image. I have a 3.5-10x40mm Leupold and cannot see any reason to have gotten a 50mm objective other than they have an adjustable objective for parallax.

Most find no practical use for the 50 mm scopes for twilight hunting. The only possible exception might be a scope where you insist on an adjustable focus/parallax set up and hunt in very dark forests in cloudy/stormy weather. I doubt it, but possible.
They sit higher off the rifle and get knocked out of zero much faster than the smaller 20-32 mm scopes. In fact, Ray Atkinson over on the Accurate Reloading Board, refuses to use anything bigger than a 20 mm scope because of this problem. He has no problems during twilight with a VariXIII, 1.5-5X20.
As far as low light, or even night hunting, is concerned, any good 6X, with a heavier than normal reticle should work. The biggest factor is magnification, not objective size or coatings.
Now, if you insist on using say a 10-12X magnification, then a 50 mm begins to make more sense as it allowas a 4-5mm exit pupil. E

I swapped two 40mm leupolds for two 50 mm scopes this year and not sure why. the 4x12x50 mm sit atop a 240 weatherby mag and seems okay. the 50mm leupold sits atop a model 70 300 wms and appears bulky. I would say that 40mm is max for a general purpose hunting rifle. 50mm fine for special applications.

For the majority of situations, I like the 40mm better. However, there is indeed a difference in low light situations between the 40 and 50mm. I have tested this myself. At dusk and at night, I have taken a Leupold Vari X III 3.5x10x40 and a Leupold Vari X III in 4.5x14x50 and seen how well I could resolve tree leaves at 572 yds. I got the best resolution with the 40mm scope on 8X, and best resolution with the 50mm scope at 11X. Further, I could see much more detail at 11X than I could at 8X. I have tested this more than once.

I recently checked light transmission with two other scopes, a Leupold Vari X II and a Burris Fullfield II. Both were 3x9x40. I was illustrating to my father-in-law that the human eye will open up to a max of 7mm, but each person was different and the older you got the less exit pupil you could use. interestingly enough, both of us saw the brightet picture at about 6X. I am 43 and he is in his mid-70s. This worked out to about a 7mm exit pupil for both of us.

All this shows magnification is a bigger factor for twilight viewing than exit pupil. That is why best resolution comes at a higher power, even when the brightest picture is at a lower setting.

Blaine

You should read muledeer's "Optics for the Hunter" he covers this topic pretty well. The 50mm scopes are designed to improve your vision in low light conditions. They have the disadvantage of of being heavier, not as reliable and having to be mounted further away from the barrel.



Low light vision:



1) Exit pupile is determined by the size of the front objective divided by the magnification. However, your eyes have a max exit pupile that they can make use of (open). This varies and generally depends upon your age. A young person can make use of no more than 7mm, Middle age uses about 5mm and old make use of 3-4mm.



2) Higher magnification effectively moves you closer to the object you are looking at. At night time it is easier to see something if it is close so higher magnification improves your vision in low light conditions.

That's what I had always heard too, but the expereince I posted with my mid 70s father-in-law (who wears thick glasses, bi or tri-focals) kind of goes counter to the 3-4mm exit pupil being all you need when you are older. It would be interesting to hear from other guys in their 70s as to what they see best with.

Blaine

I think that a larger exit pupile is better because it is easier to align your eyes up to it.

Also, I am not sure about the trade off between exit pupile size and magnification. Is it better to have a 3mm exit pupile with 20x power or 5mm exit pupile with 10x power ?

I'm not sure either. I do know that a 3mm exit pupil at last light doesn't work for me. But a 5mm always does. Actually a 5mm often works on a "bright" night. E

copper,

The advantage of a larger objective lens such as a 50mm is to allow a larger exit pupil when using higher magnifications levels. For example, with a 40mm scope, on 10 power, the exit pupil is 4mm, if you have a 50mm objective, the exit pupil is 5mm. The 5mm exit pupil number is what I have heard is the maximum diameter that the human eye can utilize.

The big advantage is at twilight and long distance, you can crank your scope up to a higher power setting and not have it blackout.

I have 50mm scopes on rifles that I hunt with out west. For most of my east coast hunting, I use 40mm scopes as I usually leave them on lower power settings, I.e 4 - 7 power.

So the bottom line is the bigger objective scopes can use higher power settings with the same image brightness as a lower power setting on a smaller objective scope.

Of course assuming all other things being equal. I highly doubt a trashco 50mm will be brighter than ANY Leupold under any circumstances !!! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Tony.

Hicountry, I'll have to disagree with you. The light gathered by
the objective is proportional to its surface area, which is
proportional to the square of the objective&#8217;s radius. Therefore,
a 50mm scope will gather 56% more light than a 40mm scope.
To eliminate the exit pupil debate, you can set the 50mm scope to
5/4 the power of the 40mm scope and then you should get the same
exit pupil in both cases, only 56% brighter in the 50mm case.
Aic

The formula for twilight factor would answer this. I do know it is more heavily weighted toward magnification, which is in agreement with my own expereince. Anyone have it handy?

Blaine

Pard you sport the Trashco of your preferred formulae,slip me a Leupie 6x42 and we'll see what can be had with what(grin).

I'll toss you the first poke and happily bat clean-up. Should it comfort you,I'll happily allow you to add on ANY device you wish to the Trashco's objective,so as to further humble me.

I'm feelin' "shooty"...................(grin)

Should add... that "shooty" is a mindset.

Spike will tell ya'................(grin)

Stick,

The 6x42 Leupie has a 7mm exit pupil and a minimum number of lenses (since it is fixed power). Because of all that, it is incredibaly bright. In fact, it is the brightest scope I have ever looked through, bar none. Having said all that, there are situations where more power with less brightness equals better resolution.

That is why even thogh my eye can make use of a 7mm exit pupil, I can see more detail with my 40mm Vari X III at 8X and the 50mm Vari X III at 11X--even though they provided their brightest pictures at 6X and 7X respectively. No doubt the 6x42 would indeed be brighter than either of those variables set at 6X, but it would not match the resolution of especially 50mm scope set at 11X.

I will say it was very eye-opening (pun intended) when I tested this. You would not have convinced me that magnification was such a huge factor in dusk and night resolution.

Also, this is certainly no criticism of the 6x42.................

Blaine

That were ducky.

Purchase the Trashco that meets your aforementioned criteria and prepare to get "shooty".

I eagerly await your selection AND findings(grin).

My point were/is,that lofty specifications numbers,do not a well rounded glass make.

I'll come full circle and state simply if'n I cain't make it out via 6x42mm Leupie,it is long past my bedtime,regardless of numerical designation,moon phase or particular tide.

Your mileage may vary.................

blaine,

That is why IMO, a Leupie 3.5x10x50mm is about as good as it gets. The 4.5x14x50mm is good, but the most usable power under low light conditions is 10 power. At least with a 50mm obj.

I've got (3) 3.5x10x50mm's and one 4.5x14x50mm. Other than at the range, there is no big advantage to the x14, especially taking into account the size/weight of that thing. I have the x14 on my 7 Rum, thinking it might come in handy. Not so sure.

Big stick,

With you on that. The only thing trashco's are good for is hammering nails !! I am not too sure about simmons either. Had a whitetail classic on my muzzleloader as did my buddy. Both failed....his fogged first day out, mine at least lasted a couple of years, until 1/4 click equaled random groups ! I ended up putting a Leupie 3x9 on the ole smokepole and put the simmons on a Pre-64 Model 88, .308, that I had re-barreled. The gun shoots 1/2" or better @ 100. One day at the range it suddenly shot 6" groups....WTF !!!! <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" /> It shot the simmons loose.

I will say to simmons credit, they stood behind it. I sent them a whitetail classic 3.5x10 for repair and they sent me back a new Aetec 2.5x10x44 !!!! Not real sure about the quality of the Aetec, optics look good , but I am a Leupie a-holic. Wondering whether to use it or not. The model 88 is naked and the scope is still sitting in the box, once burnt .......

Tony.

I'm sweet on the Leupie 3.5-10x myself,though I prefer mine unleaded(40mm).

A most versatlile glass IMHO and very tough to boot.................

Blaine, I&#8217;ll have to disagree with you as well. There is no way a 6x42 can be brighter than a 3-10x50. Also the higher power might give you better resolution.
As a very scientific proof I can use the following argument: Nothing comes for
free and with a 50mm you get a lot of bulk and weight&#8230;
The 6x42 might be the scope of choice when you consider everything you need from a scope, but claiming it&#8217;s the brightest, I think it&#8217;s a little biased and religious claim <img src="/ubbthreads/images/graemlins/blush.gif" alt="" />
Aic