40 versus 50 mm

[Hoytboy247]

I’m new to this site, and I’ve noticed a lot of people moving to 40mm objective scopes as opposed to the 50mm I’ve always been told is better. Why 40 over 50?

 

[Samson7x]

Weight savings.

 

[Hoytboy247]

Does the weight savings outweigh the brighter sight picture?


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[MuleyFever]

Does the weight savings outweigh the brighter sight picture?


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That would be a decision for each person based on their needs.

 

[762 ULTRAMAGA]

I’m new to this site, and I’ve noticed a lot of people moving to 40mm objective scopes as opposed to the 50mm I’ve always been told is better. Why 40 over 50?

I think it really depends on what kind of shooter you are.
If you take your rifle to the range the weekend before opening day and shoot a minute of deer from a bench at 100 yards then a 40mm objective is all you need.
What I've seen is that 40mm scopes almost always have really finicky eye boxes and tunneling issues compared to 50mm objectives.
Also image quality is better with 50mm especially in low light where it really counts

 

[Samson7x]

I think it really depends on what kind of shooter you are.
If you take your rifle to the range the weekend before opening day and shoot a minute of deer from a bench at 100 yards then a 40mm objective is all you need.
What I've seen is that 40mm scopes almost always have really finicky eye boxes and tunneling issues compared to 50mm objectives.
Also image quality is better with 50mm especially in low light where it really counts

This is a generalization. It all depends on glass quality and lens coatings.

 

[Pickettpuncher]

I’ve read that the eye cannot tell the difference between 40mm and 50mm concerning the light cpap abilities. For myself, the weight, and getting the scope mounted low are my top priorities. If there’s some truth to the eye box I could see the advantage.

 

[Wrench]

Most people in their 30's and 40's can shoot past legal light with a top quality 32mm scope.....and can't shoot at the same time with a cheap 50mm.

Glass and coatings play a HUGE factor in resolving power.

 

[DropTyne]

With good quality glass I am able to hunt well past legal shooting light with my 36mm-42mm objective scopes. Granted my scope may be set on 6x magnification with some of those. However, I see no benefit for me of higher light transmission (larger exit pupil) for the penalty of added scope weight to go to 50mm.

Also, a 50mm scope seems bulky to me and seems to catch on things a lot more than a scope 42mm or less.

Some folks who can hunt later than I am allowed to or prefer to keep their scopes cranked up on the max magnification at all times may prefer a larger objective.

 

[762 ULTRAMAGA]

This is a generalization. It all depends on glass quality and lens coatings.

It's science not generalization
Take two scopes of the same model that offer both objectives and spend some time behind them, I mean in the field not Cabelas
Edit: The difference is even greater the higher the magnification

 

[Maverick1]

I’m new to this site, and I’ve noticed a lot of people moving to 40mm objective scopes as opposed to the 50mm I’ve always been told is better. Why 40 over 50?

Because 50 is bigger than 40.

Signed,
Captain Obvious.

 

[Samson7x]

It's science not generalization
Take two scopes of the same model that offer both objectives and spend some time behind them, I mean in the field not Cabelas
Edit: The difference is even greater the higher the magnification

In that example, yes you are correct. Your original statement was a generalization.

Back on topic, I prefer <50mm from a quality manufacturer to save some ounces. Currently testing the mk5 with 44mm objective at 26oz.

 

[Flyjunky]

Most people in their 30's and 40's can shoot past legal light with a top quality 32mm scope.....and can't shoot at the same time with a cheap 50mm.

Glass and coatings play a HUGE factor in resolving power.

True, the quality of glass plays a huge part. The other factor is how the user is using that scope. If you're sitting on a ridge waiting for game to come out at last light 600 yards away and you have the scope cranked up to 12+, you'll like the 50mm+. As we all know, all things being equal the bigger the objective the more light, especially when the magnification increases.

 

[762 ULTRAMAGA]

In that example, yes you are correct. Your original statement was a generalization.

Back on topic, I prefer <50mm from a quality manufacturer to save some ounces. Currently testing the mk5 with 44mm objective at 26oz.

I really like the mk5 3.6-18x44 but it does have some of the issues I mentioned
I also had the 5-25×56 and it was pretty drastic how much clearer, brighter, and easier it was to get behind.
Granted it's not apples to apples given the ultra short design of the 3.6-18 model, I wish leupold offered it in 50mm it'd probably improve the image quality

 

[2rsquared]

I read somewhere that the human eye has an average pupil size is 5 mm. So a 40 mm objective scope set at 8x, has the same amount of light transmission as a 50 mm objective set at 10x....all things equal.

The larger objective allows for more light transmission at a higher magnification. May also allow for a wider field of view. As others have said, the larger scope is going to be a bit heavier, albeit just a few extra ounces.

In low light situations, it is actually better to dial your scope down a bit to get a brighter sight picture.

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[Newtosavage]

All I know is my 6x38 Weaver was every bit as bright as my 8x32 Conquest HD's in low light in Colorado when I was trying to decide whether to take a shot on a 4x4 at 300 yards on opening day.

Stands to reason since that's 6+ exit pupil vs. 4. I figure if I can't see what I'm shooting with a 6+ exit pupil, I have no business shooting.

Not everyone needs 50mm and I sure don't want to carry one all day at 9k.

 

[BRTreedogs]

Does the weight savings outweigh the brighter sight picture?


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You only need to be able to see well enough to distinguish your target and fire.
Your using binos and spotters to acquire your target.
You shouldn't be glassing from you scope..
If you drop you binos and get on the rifle any quality scope you should be able to reconfirm the animal you found and fire.

 

[762 ULTRAMAGA]

You only need to be able to see well enough to distinguish your target and fire.
Your using binos and spotters to acquire your target.
You shouldn't be glassing from you scope..
If you drop you binos and get on the rifle any quality scope you should be able to reconfirm the animal you found and fire.

This is very subjective
I agree that 50mm gains you very little versus 40mm if you're on 3x for a 100 yard lowlight shot.
I've made the majority of my kills over the past 5 years beyond 500 yards at last light, usually set at 15x.
There's a tremendous difference in what a 50mm objective gets you over 40mm in these situations.

 

[BRTreedogs]

This is very subjective
I agree that 50mm gains you very little versus 40mm if you're on 3x for a 100 yard lowlight shot.
I've made the majority of my kills over the past 5 years beyond 500 yards at last light, usually set at 15x.
There's a tremendous difference in what a 50mm objective gets you over 40mm in these situations.

That is just not my experience.
As soon as I could identify my last bull at 467 at first light with an 80mm swaro sts my 30 year old 40mm 1inch tube vx3 had no distinguishable difference and MR. Bull couldn't tell a difference ether lol.

I'm not saying there is no difference at all, but I all I'm just trying to do is distinguish an animal well enough to fire a round.
Unless the sight picture is so poor i can distinguish the animal from others in the group imma send it.

 

[KoolBreeze]

My understanding has always been that the only time a larger objective makes any difference is when the magnification is set high enough that it reduces exit pupil of the scope to a size smaller than the exit pupil of your eye. So if you had 3 scopes that were the equal except for the objectives being 40mm, 50mm, and 56mm, they'd all be equally bright up to roughly 5-6x, depending the size of your eye's exit pupil. But at higher magnifications the larger objectives would be brighter.

I hunt in the woods 95% of the time, so I've always gone with something in the 40-44mm range since my scope lives at 3-4x 95% of the time. But the older I get, I can definately tell the world is not a bright or as sharp as it use to be. I started wearing glasses a couple years ago and they have the transition lens. I can't even wear them while hunting at dawn/dusk due to how much they reduce the brightness of the woods. Am I missing out by not going to a larger objective?