The long article that followed explains in great detail the physics involved. The summary of that physics is that in 99% of hunting applications (basically anything under 20x at certain ranges) there is no difference - all else being equal.

If there is a perceived difference otherwise, then either it is only perceived vs. real or some other factor besides the bell size (better coatings, better lenses, slightly more light/less shadow, etc.) is the reason. Not the 50mm objective.

Big bells can help some with high magnification. Still, optics quality is a much more important factor. Lower to mid-level scopes with big bells are a waste, no matter the application. Only the highest quality high-magnification scopes can actually benefit from the larger objectives under the best of circumstances.

Nog, not to be argumentative but the first 10 years of my professional career was in research and development. How any data is assimilated and presented can and does skew the results and can be presented in multiple scenarios to support multiple theories. How much the 1% of all hunting conditions impacts the actual hunting I participate in and what are the most productive times for me is what I find pertinent. I have been around long enough to trust my own eyes first.

I’m not doubting your eyes or trying to be argumentative (I thought I was clear to explain that) - simply presenting the facts I have gleaned on this subject based on quite a bit of research on it.

The science is basically unassailable that for the OP’s scope (10x maximum magnification), the 50mm objective is a waste of money to add useless extra bulk and weight. The human eye has its limitations. Those limitations can be objectively quantified and applied to the physics of light transmission properties of differing objective sizes. It’s as simple as that.

I am sure it is black and white to you based on what you have read but it is not as simple as just light transmission and exit pupil. The first thing that goes as darkness approaches is the ability to discern fine detail. The optical sweet spot of the glass is the last place you lose that ability. The optical sweet spot in a 50mm lens is larger and thus renders a larger portion of the image where I retain the ability to discern fine detail and thus a more useable image in low light.

Are 32mm scopes as good as 40mm?

By far the most effective real-world move to make to gain more low-light hunting time is simply to turn down the magnification on your scope.

Depends on what factors are important for your application.

Under certain magnification levels. The point of NP's post was to say that under certain magnifications, the difference in brightness is dominated by factors other than the objective size.

I'm sure at 4x, the difference between 32mm and 40mm is nonexistent.

What if your tube diameter was the same as the objective?

This is what I tried to explain earlier. Hopefully the link makes more sense than I do.

https://www.safaribooksonline.com/library/view/astronomy-hacks/0596100604/ch01s08.html

I never do 50MM objectives if I can get the same scope with a 40MM objective. The negatives of a 50MM objective far outweigh the positives. And the positives are mostly perceived, not real in IMO.

There’s a reason marketing execs make way more than scientists.

If you guys honestly think that 2 ounces of weight and 0.2" of "bulk" is going to be noticeable on a hunting rifle then I'm not sure how you're able to even carry a 8 lb rifle anyway.

The post above said the negatives far outweigh the positives....personally, I don't think 2 ounces and .2" is a negative because it will not be noticeable. The main difference like others have posted is that in low light (the time when it matters most) is when you will have a difference. A 50mm scope at 10x will be equivalent in light transmission to a 40mm scope at 8x. To me, that is not insignificant when you need to count points or try to estimate antler spread at dusk at 250 yards.

If the main disadvantages are weight and bulk, then those are almost completely inconsequential.

To me they do far outweigh, because there is no gain to the 50 mm and it is bigger/heavier/requires a higher mount/isn't as appealing/costs more/ etc.

Its not that its functionally worse, its that its functionally the same and every other aspect of it is negative, other than perhaps self gratification.

So you think you will notice 2 ounces and 0.2" on a 9 pound rifle? You realize that's just over a 1% weight difference and 3% size difference.

You guys need to hit the gym.

I understand not wanting to pay the extra money, or even disliking the looks...but the weight and size argument is silly when you actually compare the numbers.

This would be true if the objective was the limiting factor in light transmission within the optical path. According to a number of optics experts, that is not the case.

I agree about the weight argument being mostly insignificant. The size argument becomes important from the standpoint of being on a somewhat compact hunting rifle, or the fact that it moves the centerline of the scope up 5mm from the stock. And it costs more. And for all that tradeoff, you get essentially no extra optical benefit for 10x or less scopes.

That's what binoculars are for. I've found no practical difference in the field hunting between a 40 and 50mm objective.

Doc I mentioned it earlier and gave a link. The gain in a 50mm over a 40 is lost past 7x and that’s assuming you have youthful eyes. At the 8 or 10x they you mentioned they will be identical to the eye.

I think you got that backwards WP. The gain in a 50 over a 40 doesn’t start until 7x. Doing some quick math — 50mm / 7x = 7.1mm or a 20 year olds pupil (for arguments sake) based on your article. A 40mm / 7x = 5.7mm which is a smaller exit pupil than entrance (again based on your article). Up the mag and it just get worse for both objectives but the 50 always comes out ahead.

Try this link to get a better explanation - http://huntingoptics.net/blog/what-is-exit-pupil-in-hunting-optics/

You may be right but the way I read it the gain begins around 6 and ends around 7x. I could be misunderstanding. Let me read the other article.

TLew I may still be wrong but after reading the article you just posted I understand itthe same way as I did before. I need better understanding. Lol

No I don't think I would notice the extra 2 ounces or .2 inch. But I cant justify spending extra for something that is a negative in every category except for being able to look over at the nex guy with a measly 40mm objective and say haha mines bigger than yours is! I have had trouble with 50 mm scopes in the past not fitting well in soft cases also.

The range of useable exit pupil varies individually. Some may have an entrance pupil as small as 4mm while others are able to dialate as wide as 7.5mm. Most fall somewhere between the extremes. In other words what is indiscernible for one may be useable for another. An optometrist can measure your entrance pupil if you want to go to the hassle of doing, it or you can simply look through various scopes to determine what is useable to you. A 40 mm objective at 7 power has an exit pupil of 5.71 while a 50mm objective at 7 power has an exit pupil of 7.14. So there is more available light that translates to a brighter image IF your eyes are able to utilize it. That does not address coatings, FOV, or the size of the optical sweet spot where visual acuity is the greatest in various scopes and objective diameters. In good lighting it is a largely a non issue. Based on that, the reality of scope selection for me is based on what I am actually able to see and if there is enough realized benefit for the additional cost.

Edited to add: for most use I prefer a 40mm-42mm scope, but the 7RM I use primarily out of a stand to hunt mature whitetail trophies with has a 50mm Swarovski sitting on it. For me, some days it marginally extends the time I can ethically shoot.

If you really want to have the optimal setup for low light conditions, by far the best method when the light fades is to use your binoculars to determine if the buck (or other animal) is one to shoot, pick up your rifle, dial it down to a low power setting, and kill it.

My Swaro 10x42s beat the snot out of most any scope in low-light conditions. Mainly because they have dual ocular lenses that deliver light to both eyes and those ocular lenses are held right next to your eyes (no eye relief necessary for binoculars), delivering virtually all possible ambient light. (8x42s would do even better, but I like 10x for a bunch of other reasons that have nothing to do with low light performance.) All binoculars will beat all riflescopes of the same quality in this regard. Again, physics.

A little more light reading on the subject of big bells:

Nogales, you nailed my setup except, I have the 10x42 Swarovski binocs but I see better in low light with a pair of 10x42 Zeiss Victory HT so they are what I now use most of the time. FWIW I am the same in regard to 8x vs 10x binocs.

One other tidbit that is contrary to Chuck Hawks and what others that have read instead of done may say, is the 50mm Swarovski is mounted in dual dovetails and MEDIUM rings. Solid mount with optimal for me cheek weld.