There are a lot of 40-44mm objective scopes out there as well as 50mm objective scopes. For low light hunting and shooting do the 50mm and above scopes really help that much with light transmission? There are some nice 56mm scopes out there also. Do they help that much more then the 40-44mm?

Heres the simple run down. If you are over 40 your pupil can only dilate to 5mm. Take the diameter of your objective in mm and divide by the power you are using. ( i.e. 40mm divided by 10 power= a 4mm exit pupil) The exit pupil is the amount of light transmitted to your eye.. Do the math on the scopes you are considering for your answer.
The ideal is thought to be 7mm exit pupil+ simply because it gives you a margin of error for poor placement of your eye...

Quality of glass and coatings matters as well.

So let’s look at the Trijicon 2-10x56mm. If I’m using only the 2 power divide 56 by 2? 28mm exit pupil?

If you're willing to out up with the physical requirements of the big objective scope it will allow you to stuff more magnification into a given exit pupil.

Yep, most of which is wasted not getting past the aperture in the front of your eye

Ok then. So just stick with 40-44mm objectives and low magnification

OTOH, too small an objective will make some of those Xs unusable in bad light. I don’t have big ones on all my rifles, but having one can be handy at times. The 2.5-10 Trijicon Huron HX I just mounted on my new Carbon Mini was an anvil on a Hawkeye, but it sits very low on the Mini with the rail and only brings the total weight up to 7lbs on the nose.

If you don't mind the size of the scope you can get 10x in a 5.6mm exit pupil. Magnification can make things appear brighter too.

I simply don't favor big old scopes on top of the rifles for my particular hunting purposes.

I like a 6x42 scope or a modest size variable which adjusts to that combination.

Well... a larger objective will also have greater resolving power. Showing finer detail of what is magnified.

I like using a low power and small objective on some rifles because of the incredibly wide field of view, that actually is primarily attributed to the short focal length, which generally affords fast target acquisition at short range.

At 49 my eyes aren’t what they used to be. So alpha 50mm glass has become my go to. Most of my hunting is from a big ladder or box blind.

Objective size and magnification go hand in hand. If you divide the objective size in millimeters by the magnification, the number you get is he diameter of the light beam coming out the back of the scope. Known as the "Exit Pupil". You want a minimum of 5 for low light. But for most people anything much over 5 is wasted. Certainly, no more than 6 or 7.

A scope with a 50mm objective set on 10X, a 40mm scope on 8X and a 20mm scope set on 4X all allow the same amount of light through them.

Unless there is a gross superiority of one scope over the other I'm not too worried about resolution. When there's hair under my reticle I'm aiming, not examining or birdwatching.

I have espoused upon this several times... 56mm objectives and 30+mm tubes will absolutely gather more light. I have taken them out side by side and used them both. The smaller objectives will get most of the job done... we can LEGALLY deer hunt here for an HOUR after sunset. I have been using 56mm scopes here for 40+ years because the flat out work in the dark. I certainly wish the cheaper and smaller ones worked but they really don't.

There is a reason that so many people here and in Europe use the larger objectives - they flat work. In Europe, you can actually hunt at "night" in some places...

Tubes don't gather light.

If you're sitting where I am the biggest Schmidt and Bender won't do you any good an hour past sunset.

Thanks

I used to turn my nose up at any objective over 40-44 mm . At 40+ years old now, 50mm and up look great. Although the difference in a 36 and 50mm is small to my eyes looking through the scopes ,it’s still a noticeable difference . I had a 36mm and 50mm scope in the blind last week.

The 30mm tube does offer the potential for a larger field stop, which given equal focal length would offer a wider field of view. Normally at the cost of added size and weight, and potentially making top loaders more difficult to load.

What kind of hunting environment?

The one where it’s illegal an hour past sunset, I’m guessing.

Although in many places it is legal to hunt predators or hogs after dark on private property.

Somewhat narrow pipeline right of way, tall pines with undergrowth on both sides, sun setting behind the trees, not in line with the right of way.

We can hunt hogs any time, but where I am right now a 56mm won't matter in about twenty minutes.

In the interest of honestly and full disclosure I sat on stand for some extra time. Depending on which part of the right of way you were concerned with the bigger, top quality scopes would have tacked on another ten minutes or so.

That said, a hour after sunset, no way no how.

Some moonlight can change that game with the right scope.

Yep.

I understand completely what Mathman is saying. I spent several sunsets the past week or so hunting an open strip of thinned pines. It’s 30ish feet wide or so, and I was facing north. Legal shooting light ends 30 minutes after sunset. It starts to get sketchy at 10-15 minutes after sunset. At 15ish minutes after sunset, assuming clear skies, the Tract 10x42 binos can go in the pack as the image is no longer bright enough to make any assessment of deer beyond general body size. From there I was using my rifle scope, an SHV 3-10x42 this week, until end of light. I adjust magnification until image appears brightest, which I assume is at highest magnification that my pupil can utilize what the scope can give. With the SHV, that would give anther 8-10 minutes that I could usually make an assessment of a deer at 120 yards or so. I could hold on one and shoot (essentially a silhouette) until legal time expired, but it would have had to be there 5-10 minutes prior to evaluate it. I have used a Tract Toric 50mm scope on the same stand. It gave me maybe 3 or 4 minutes more time that I could assess buck/doe/good buck/etc… At 15 minutes beyond legal shooting time, I don’t think a lens exists, at least I’d be willing to carry, would make a meaningful difference.

Now, when I walk out, I walk across an open area that is at less 50 yards x 50 yards. There, and in fields, it is a completely different scenario than the open lane in the pines.

When I still had some Vari-X IIIs in the lineup, the 2.5-8x40mm was surprisingly useable under a full moon. The VX-3i that replaced it was noticeably brighter in daylight, but I never did check that one out in full moon conditions...the need and opportunity just never came up. All those Leupolds went bye-bye, but not on account of the glass quality.

My deer rifles typically wear 3-9x40s, 2-7s, or something like the 1-6x24 on my Grendel. The big Triji was purchased in hopes of turning it on low-light yotes and such. I will say that the 300 yard range near me has some shadows at times and something like a 4.5-14x42 struggles at the top end in that light. Last time I had the 2.5-10x56 out there, I had no trouble seeing into those shadows. It’s lit too, and the center crosshairs are pretty fine. Hope to get it out in the dark and hopefully some snow once night shooting gets legal here in January. It doesn’t look too big on that Mini to my eye, but I’ll try and get a pic posted and see what the other kids think…..

Exit pupil is extremely over rated. I compared a Minox 13X56mm (two "scopes") with a 50mm rifle scope set on 13X in a low light situation. The rifle scope lasted two minutes longer.

One thing to mention--and I could be wrong...but isn't an exit pupil greater then 5mm to 7 mm generally useless, owing to the limitation of the eye's pupil dilation?

And then only when your eyes are fully dark adapted.

In bright daylight your pupil will be much much smaller.

But if you set up a green laser to partially illuminate an area...

Hog was shot 45 minutes after sunset in thinned pines—40mm Leupold Mark 4 on 6x. Binoculars were 7x42 Dialyts.

May I suggest

a kill light

or

a night vision optic

or

a thermal optic.


Amazing what those optics do for dark-thirty and beyond hunting

ya!


GWB

Here, and in most places I’ve hunted in the East, legal hours for deer begin and end 30 minutes either side of dawn and dusk. Most scopes will get it done in the open, but in the timber it gets dicey even well inside the legal limits. Lights, NV, thermal, etc are generally not legal options, again for deer and other game. Yotes and other varmints are different, although in WV, bobcats can't be taken under the lights like yotes, foxes, and the other minor predators, for reasons they don't explain.

No piggies here just yet, but they're comin’! Get closer every year, courtesy of misguided transplant efforts by dumbazzes. Not sure I’ll still be in the game by the time they do, but it’ll be interesting to see how the DNR handles the opportunities.

I'm 45 and my Leupold LPVO at 24mm objective gives a big FOV and good low light capability. How is this explained with the exit pupil equation?

I quit hunting big game years ago and concentrate on hunting coyotes mainly and other predators when presented. I shoot a number of 1-4x20s and 1.5-6x40s and if I can see them coming with my bare eyes I can kill them with my scope. I have no restrictions on shooting hours other than no lights here.

I'm 75 11/12 yrs old have had double cataract surgery done 20 yrs ago. I do keep up with prescriptions for corrective lenses for my glasses and see and eye doctor every two years. If you find you need bigger scopes to see game I would suggest a trip to a regular eye doctor, not the lens fitter at Walmart. I eye problems can sneak up on you, I had no idea I had a problem until I started having problems with car lights at night looking like big stars. After the surgery I couldn't believe all that I wasn't seeing even the winter trees had tiny branches I never knew were there.

All eyes process things differently.
The equation does not change. Coatings and all the trimmings that go along with higher quality lens does change things.

I have been using straight tubed 24mm objective scopes for many years. I used popular USA made straight tubed 20mm objectives prior. The first time that I looked through an upper end 24mm, I was hooked.

My European 24mm objectives are pretty dang good. But, the 42mm objectives of equal quality still have some advantage for me. As would the 50mm over the 42mm. Though, I don't think quite as obvious as the 42 vs the 24.

A few years ago, I got a pretty good buy on a Leupold VX-5HD 1-5x24mm. To my eye, this scope gives a very good lower light view for a 24mm objective. I will say the same for the Tract Toric 1-8x24mm.

As others have stated "low light" conditions vary. The time past sunset is not the single qualifying benchmark.
Significant low light difference in open tundra, fields, meadows than in the timber and valleys with timber. And of course the atmospheric conditions can make it worse.

I have a Swarovski 6x42 that is very bright and very clear, but it doesn't have what qualifies for me as a low light reticle. If it had the same heavy duplex that my VX-III 1.75-6x32 had it would be super as the light fades.

That's easy; FOV is a function of focal length, distance and CoC when the aperture is constant. In an LPVO, the focal length will be quite short and at low magnification, the CoC will be larger so you will have a very large FOV with little magnification. I haven't a clue what the specs of your Leupold LPVO are, but it probably has a low top magnification so the exit pupil will always be a good size. If your LPVO goes to 8X or 10X, you will see a drop off in exit pupil size, but you would probably not be using high magnification at night.

Great info

Actually, that's a common misconception. Most of my moonlight shots are at 8-10x and sometimes higher. You need magnification to discern detail at night. For example, a 150 or 175 yard shot on a hog in daylight is a piece of cake with 3x or 4x. But at night, you'd have an extremely difficult time at those lower magnifications and likely couldn't tell for certain if the animal was broadside, quartering, etc. -- or even if it's a hog at all and not a dog or calf.

With most any amount of moon I can run a Kahles all night...

Exit pupil is equal to the objective diameter divided by magnification on the maximum magnification. It is also often the case in the upper half (approximately) of the magnification range. On the lowest magnification, I am not aware of any currently-made variable riflescope (maybe there some target type ones, but I have not tested those in a while) where the entire objective lens is used on the lowest magnification. For example, taking the Trijicon 2.5-10x56 mentioned earlier in this thread, it has exit pupil of approximately 16mm on 2.5x. That means on low power it only uses about 40 millimeters of a 56mm objective.

As far as how much exit pupil you need for low light use is somewhat individual, but you generally want it to be a bit more than your eye pupil. There are several good reasons for that. I hope Rick does not mind if I post a link to my website, but I did a livestream on that exact topic about a month ago:
https://darklordofoptics.locals.com/post/2946143/exit-pupil-and-how-the-eye-works

I travel a good bit for work and these are the topics that are easy to discuss without props, so I can cover them when I am on the road.

Lastly, when it is truly pitch black, thermal is the way to go. An hour after sunset is doable with some environments with conventional scopes, but that really depends on the terrain, where the moon is and at what phase, the cloud cover, etc. There is a reason why you want an exit pupil larger than your eye pupil in low light.

One of the things that happens is that your visual acuity goes down when the eye pupil dilates, so this is something you want to do some experimentation with. On top of that, your eyes depth of field goes to hell in a handbasket. The way you perceive the reticle, for example, can change substantially, especially if you have not checked eyepiece focus with dilated eye pupil.

ILya

Very good point. I find that etched reticles stand out significantly better in low light than wire reticles.

short answer in short NO. the reality is in low light you have trouble identifying the quality of animal you're shooting at if the distance is very far. if the distance aint that far, say 200 yards. you can simply dial the scope down to 4 or 5x in which case as long as its not a 70's redfield the glass should be decent enough to make the shot.

all the scopes I hunt with are capable of shooting well beyond legal shooting light.

Years ago I lived in the Outer Banks.

I used to take my Jeep out on the beach in the crazy bright summer sun.

My girlfriend was obsessed with blow jobs in public.

I put on her Varnets once (she didn't need them at that moment).

Holy smoke... them durn Europeans sure understand lens and coatings...

I have been a Euro junkie ever since.

ILya,

Thanks for injecting some optical reality into this thread. I had been holding off, mostly because of eventually growing weary of battling optical myths among hunters.

But I also doubt that most following this thread will be able to understand (much less appreciate) your post.

Apparently you are doing well!

Best,
John

Then why are mfgs making 56mm objective scopes????
What’s the market and purpose?

So that you can dial to 5-6x and still have a comfortable ~10mm exit pupil. The smaller the objective, the lower you have to go to maintain the same exit pupil size.

FWIW, yesterday I actually managed to get to and into my stand in very thick brushy cover before legal shooting time, which was 0630. Clear sky, bare trees. Spent some time looking around and checking whether or not I could see well enough to shoot through my scope, a Trijicon Accupoint 3-9x40 with green dot at the center of a duplex, set naturally on 3. I was expecting any deer to come on one of the trails that run from 5-25 yards from the ladder stand, so that’s where I was checking. When at last I was satisfied I could make out a deer within that space well enough to shoot safely and effectively, I checked the time it was 0628. Before that, while I could certainly have made out a deer and identified its sex, detecting obstacles between us might have been dicey. The buck that finally volunteered at 0915 would have been pretty safe at 0630, because he was 50 yards out, facing straight at me in head-high weeds and briars. Even if I had seen him there, not at all certain, determining if the path was clear would have been difficult. Perhaps if I turned up the power a bit I could have made stuff out better in that light, but I might also have lost my opportunity while futzing with the power ring.

One other thing I discovered while peeping through the Accupoint is that at first light, the tritium was providing all the illumination for the dot. I covered the little window with my hand and its brightness didn’t change. It was just bright enough to draw my eye, with no flaring or bleeding over into the other parts of the image. When I took my shot, it was very clear against the deer standing in sunlight. Where it falls short, is when under cover in daylight, as when under a covered shooting bench or in a shooting box or pop-up. The tritium isn’t bright enough to be seen, and the fiber-optic won’t collect enough light either. Those who hunt from such structures and want an illuminated reticle should go with something that uses a battery. For me, the Accupoint does what I need, and is as small and light as other 3-9s.

The riflescopes with 56mm objectives are usually high magnification riflescopes. You need a larger objective to get a usable exit pupil and for the increased image resolution.

For example, my current F-TR competition riflescope is a March-X 10-60X56 HM, which I use at 50X all the time. The exit pupil size is 1.12mm and this means I have to be properly behind this riflescope to see anything. The 56mm objective forms the image at the front of the erector tube with much more resolution than with the same glass in a 40mm, or 36mm, or 24mm objective, at the same focal length. You can go read about Dawes limit, if you want to learn more. The larger the objective, the greater the resolution (with all the applicable caveats). The downside is that the DOF is greatly reduced in a 56mm objective, compared to the 40mm, and smaller.

This scope at 50X provides me the detail that I need for shooting a 1000-yard competition on an NRA LR1FC target where the X-ring is 5 inches across, and I can distinguish each of the rings from the other concentric rings. I used the low power 10X when I first sighted in the riflescope, and I don't think I've ever used at less than 40X at first and then 50X for the last couple of years.

More recently, I have been testing a March-X 8-80X56 HM set at 80X on the same target. The exit pupil is a tiny 0.7mm, but that is not an issue when you are properly behind the riflescope. I have used it at 50X and 60X, but 80X is just too attractive to mess with the lower magnifications.

This is a different world and use from most of the users here. These scopes are much rarer than hunting scopes usually discussed here, but they have their users and that's why some manufacturers produce them.

I will also state that the exit pupil at the low end on these scopes (and probably most scopes with a base magnification greater than 3X) is definitely not what you would expect if you divided the objective by the low magnification. It's smaller, and sometimes a lot smaller.

Thanks, John.

I am doing well, but my life has gotten even busier, so I do not get involved in quite so many battles. If I see an interesting topic, I swing by, say my piece, and move on. I figure if I get enough information out there, eventually there is going to be enough critical mass to make a difference. I do try to check back on the threads where I have commented.

Now that the hunting season is almost over, I will have more time for a bit. I have a few ideas for new videos and articles, some of which will be addressing core understanding issues more so than just product reviews.

ILya

This. I recently shot a hog on a feeder at 50 yards in very low light. Several hogs were jostling each other at the feeder and while I could see all of them at 3x, I couldn't really understand what was going on: which hog was in front of the others, etc. I cranked my Nightforce 3-10x42 SHV up to about 6-7x and was able to see what was important.

Had the hogs been any farther, I would have cranked the scope up even more.


Okie John

Good post and paragraphs.

Thanks for taking to time.

So few actually use an optic in low light.

Magnification increases the "brightness" of the image.

On 10X the hunter is "sort of" 10 times closer.

The best image will be at the max zoom that offers a bigger or equal exit appature to you eyes pupil.

Add in the better resolution of the large objective and a significant gain can be had in low light.

Thanks, Okie John, for some real-world input

Nobody has mentioned lens quality. You can put a paint bucket size objective on a cheap scope and it want make it any better.
My first quality scope was a steel tube Kahles. 3x12-56. Followed by Swaro aluminum tube 3x12-56. For the most part twin brothers. These models preceded the Swaro PH series scopes. They were also the last scopes that lead was used in making the lens. Lens quality dropped because of this.
Basically you get what you pay for. Hasbeen

Image brightness is solely attributed to exit pupil size, up to the point that it matches the size of your own dilated pupil. If the exit pupil is larger than your own pupil, then you have effectively reduced the aperture of your scope. So yeah, in that sense the brightest image will be perceived when the exit pupil matches your own pupil.

But magnification on it’s own does not increase brightness. Only the size.
Although a point source of light won’t lose as much brightness as objects that are absorbing or reflecting light as magnification increases.

Many objects will disappear as magnification increases and the exit pupil gets smaller than your own. But given enough light to illuminate your target, you can perceive a sharper image down to about a 2mm exit pupil. Because this centers the light on the most sensitive part of the eye.
Although with a dilated pupil you may perceive more details with higher magnification, given enough light on the target, the image will begin to blur with an exit pupil much smaller than 2mm.

First up
I am not a Scope Expert.
Or a Firearm Expert.
That Said

I put a March 8 X 80 56mm on my Springfield M21
I took it to the range ( I know Just Paper Targets)
The first time out I was shooting about an half hour after everyone else had packed up.
Even the open sight guys.
I gave up on everything except the March.
This Scope is amazing.
I use the 80 for a spotting scope and dial it back to shoot.
The highest I shoot is at 60 and some time 50.
My Hart beat and breathing make it hard for me to sight anything in with the bouncing Reticle.

I love this Scope and am very happy that I put the money down when I did.
The very first time I took it out I was trying to sight it in at 100 Yards and even Bagged I was loosing the Target.
I was getting Frustrated until I figured out that at 100 yards set at 80 I was looking at the grain structure of the paper Target after I figured it out and had a DU moment sun was going down and I popped off 3 shots that I could cover with w Nickle.
This was after everyone was packing up and getting to dark with open sights.

You get what you pay for some times.

LOL.

No.

Once the optic exit appature exceeds the shooters pupil there is nothing to be gained as far a "brightness".

But an increase in magnification brings an increase in brightness as 10X is 10 times as bright, sort of.

Just like being 10 times closer is brighter.

Physics, it's fun.

"Appature" is simply fhuqking AWESOME +P++! Hint.

Fhuqking LAUGHING!...............

While I love smashing on you I will admit you spell better.

Aperture.

Now post some video.

I'll wAIT, FOR A BIT.

My low light hunting has been done with my Swarovski 2.5-10x56 PH, Meopta 3-12x56, and a borrowed Schmidt & Bender 2.5-10x56. These scopes were designed for night hunting of boar in Europe. Having spent a lot of time behind these scopes at night I can say without a doubt that yes, they do help that much. With a decent amount of moonlight you can hunt all night. The reticle is as important as everything else and as one poster mentioned, you'll generally be shooting with the power maxed out to discern the detail to make the shot. There are caveats though, you're not going to get a blister pack bushnell with a 56mm objective and have it do anything for you, you've got to start with best quality glass.

There are other considerations than just the scope too. Your eyes don't completely adjust to darkness until after about an hour of low light. Remember your biology classes and how they eye receptors are composed of rods and cones, cones are for daylight vision and rods for low light. It takes about an hour of low light before you get your full night vision, that's why you use green or red lens on flashlights to avoid messing up your night vision. Bright light will bleach out your photoreceptors and it takes about an hour to get your night vision back after you've been hit with bright light. During that time you're not going to be able to take full advantage of a scope like that. Most people compare them right at dark when their eyes aren't adjusted and say they can't see any difference, wait an hour in the dark then try it, you'll see a difference. If you just want to shoot to the end of legal shooting hours then most scopes today will handle that fine, but if you want to hunt at night then those top quality 56mm scopes stand out. They've got to have some light though, if it's pitch black you're going to have to use thermal as mentioned.

It is not the magnification that makes the image brighter. Magnification only makes it bigger. And easier to see, given enough light.

It’s aperture dependent.

At night... Assuming your target isn’t producing it’s own light, a 50mm scope at 10x will be much brighter than a 50mm scope at 50x.
Just like 10x in a 20mm scope will be much dimmer than 10x in a 50mm scope.

Nope.

The bigger objective brings a bigger exit aperture and better resolution.

Magnification brings image brightness.

The issue is when you eye pupil is expanded bigger than the exit aperture and this causes a feeling of darkness.

As to scopes with large objectives being too big, here’s my Carbon Mini with the Trijicon 2.5-10x56. Total weight sans sling is 7.0lbs. Is a trifle top-heavy, but not fatally. Fore ‘n aft balance is good. I don’t think it looks too big.

Before someone asks, the scope is positioned so I can get a full view at 10x, and not whack my lovely nose with the bolt.

What size rings? Can you put scope flip up on there or is there no clearance? Almost touching the barrel?…

SWFA lows. Talley (I think) rail. Plenty of barrel clearance; the factory see-throughs fit fine, although I have to turn the one on the eyepiece so the bolt doesn’t hit the nubbin that holds the elastic. I’m pretty much over flip-ups so wouldn’t be an issue for me anyway. Might have ones that will fit in my box-o-crap, where they shall stay.