40mm Objectives vs. 50mm-56mm Objectives?

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Just wondering if any of you guys prefer a 40mm objective lens over the super-sized 50mm+ objectives that seem to be all the rage these days, especially for "tactical" type models.

I personally don't see the reason for opting for anything over a 40mm unless you're planning on shooting a lot at dusk or in the dark. Those big objectives add a lot of needless bulk and heft to the scope and requires that you mount it much higher than the 40mm.

Looking at a lot of the Nightforce line, it is obvious they are fantastic scopes, but boy are they heavy/bulky! They may offer some advantages over say a 40mm Leupold MK IV, but I think I still prefer my 3.5-10 or 4.5-14X40mm Leupolds to the comparable Nightforce offerings.

I may be out to lunch here, but my thinking is that for the average shooter really isn't in a position to take advantage of the "extra" performance offered by the NF. What do you guys think?

(Not looking to start a Leupold vs. NF fight, just size of scopes of relative comparable quality/size/performance)
 
I think you pointed it out, bigger objective is for broader light gathering and when your benched, extra weight doesn't really matters
I only have one 50mm and I got it used, couldnt pass that bargain!

but I'm sure Freud would answer it has something to do with the #####.
 
maybe its my old eyes but i find for hunting purposes the ability to get more light is really important at legal dawn & dusk which is the most productive time of day, and the extra depth of field is an asset for game identification. So I prefer a 50 mm for hunting only though. Anything else 40 mm is plenty.
 
JohnC said:
maybe its my old eyes but i find for hunting purposes the ability to get more light is really important at legal dawn & dusk which is the most productive time of day, and the extra depth of field is an asset for game identification. So I prefer a 50 mm for hunting only though. Anything else 40 mm is plenty.
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I'm the complete opposite. All my hunting rifles are either geared up with 20mm or 33mm objectives....to keep weight and bulk to minimum. My target rifle on the other hand has a 56mm obj. At 1200+ yards you start to appreciate the larger objective. I find the 33mm just perfect for hunting at any time of the day. Everybody's different I guess.
 
The key word you're looking for is "exit pupil". Your eyes can only take in about 7mm or so (if they're good - mine are bad and 6mm is about the limit). That's only in bad light when your pupil is fully dilated. During bright daylight, your pupil constricts to radically smaller than that 7mm. A 3-9x40 has an exit pupil of around 13mm at 3x zoom (plenty!), and 4.4mm or so at 9x zoom.

So to put all that together, practically speaking, you can put it up to around 5 or 6 x zoom when the light is all-but gone, and if the glass is good stuff, still see just as much light/image through the scope as you could with your naked eye (and more importantly, just as much light/image through the scope as you could with a 56mm objective lens). In the daylight, you will see zero difference, regardless.

The only time you "need" a larger objective lens is for high zoom in very low or otherwise poor lighting conditions (and they are nice to look through on a target rifle, I think). During bright daylight and/or at typical "hunting zoom", there is slim to no advantage with the bigger/heavier/larger objective lenses, and the disadvantages are self evident.
 
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My problem with Big Head is the cost. High quality 50+ glass costs lots more to make. Then in hunting situation you don't really need that.
 
The larger objective lenses are nice if you are shooting in low light conditions,however the you may find your shooting may suffer due to the fact of improper cheek weld and not a natural position from which you are used to shooting from.
 
I have 42mm objectives on all of my hunting rifles,and they are plenty bright in all legal hunting light.My scopes are high end scopes that are at least as bright as the lower quality 50mm scopes.
I only own one 50mm scope and that is my Nightforce nxs 3.5x15x50.I much prefer the Nightforce nxs over the Leupold Mark 4.
 
I prefer a 40mm on a light deer hunting rifle. Its sits down low, keeps the bulk and weight down, and gets the job done. On a decent quality 3-9x40 I have no problem seeing during legal hunting hours and beyond.
 
brotherjack said:
The key word you're looking for is "exit pupil". Your eyes can only take in about 7mm or so (if they're good - mine are bad and 6mm is about the limit). That's only in bad light when your pupil is fully dilated. During bright daylight, your pupil constricts to radically smaller than that 7mm. A 3-9x40 has an exit pupil of around 13mm at 3x zoom (plenty!), and 4.4mm or so at 9x zoom.

So to put all that together, practically speaking, you can put it up to around 5 or 6 x zoom when the light is all-but gone, and if the glass is good stuff, still see just as much light/image through the scope as you could with your naked eye (and more importantly, just as much light/image through the scope as you could with a 56mm objective lens). In the daylight, you will see zero difference, regardless.

The only time you "need" a larger objective lens is for high zoom in very low or otherwise poor lighting conditions (and they are nice to look through on a target rifle, I think). During bright daylight and/or at typical "hunting zoom", there is slim to no advantage with the bigger/heavier/larger objective lenses, and the disadvantages are self evident.
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The exit pupil is the "beam" of light that is projected onto your retina. Obviously if it is bigger than your pupil opening, not all of it is going to make it into your eye. However, that does not mean that you see just as much light through your scope as with the naked eye. The amount of light is affected negatively by light reflected off the lenses as it travels through the scope. Modern lense coatings reduce this loss to a few percent in good scopes, but it still has an effect.
 
redleg said:
The exit pupil is the "beam" of light that is projected onto your retina. Obviously if it is bigger than your pupil opening, not all of it is going to make it into your eye. However, that does not mean that you see just as much light through your scope as with the naked eye. The amount of light is affected negatively by light reflected off the lenses as it travels through the scope. Modern lense coatings reduce this loss to a few percent in good scopes, but it still has an effect.
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Yes, I know that there is some loss of light due to the lenses (sometimes a LOT of light loss if you've got a $50 scope!). However, the point still stands - that if the exit pupil is as big as or larger than your pupil, the only "improvement" you're going to get for low light performance is higher quality glass, not a larger objective lens.
 
After using 50's I find it very hard to go back to 40's, unless you're comparing budget level 50's to high end 40's. When I shop for scopes now I always go 50mm unless I am purposely trying to go for a light, carrying rifle. The extra brightness is just so hard to turn away from after you've used it a couple of times...
 
brotherjack said:
Yes, I know that there is some loss of light due to the lenses (sometimes a LOT of light loss if you've got a $50 scope!). However, the point still stands - that if the exit pupil is as big as or larger than your pupil, the only "improvement" you're going to get for low light performance is higher quality glass, not a larger objective lens.
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Well actually there again, a larger lense does gather more light, so the exit pupil can actually be brighter too, even if the same size.
But I am not really sure how large those gains would be between a 40mm and 50mm lense. I can see a real difference between a 40mm and 72mm lense though.
 
redleg said:
Well actually there again, a larger lense does gather more light, so the exit pupil can actually be brighter too, even if the same size.
But I am not really sure how large those gains would be between a 40mm and 50mm lense. I can see a real difference between a 40mm and 72mm lense though.
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Im too lazy to do the math but remember that Area of a circle is pie*r^2. Which means that area increases as a square of the increase in radius so although it doesnt seem like a large increase from 40mm to 50mm it probably translates to a large amount of surface area.
 
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redleg said:
Well actually there again, a larger lense does gather more light, so the exit pupil can actually be brighter too, even if the same size.
But I am not really sure how large those gains would be between a 40mm and 50mm lense. I can see a real difference between a 40mm and 72mm lense though.
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For me it was a matter of losing a moose that prompted me (couldn't tell if it was a bull or not) to go to a bigger lens. The following year, happened to be in the same spot, same situation (early dawn light) and filled my tag. Sounds funny, but I was actually able to see better through the scope than with my naked eye. My eyes aren't perfect but they're in decent shape (don't need glasses). I had Leupold 40mm lens before (sold it) and went to a Leupold 56mm (VX-L) which also mounts as low as a 40 coincidentally.
That morning sold me on my decision.
 
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