40mm or 50mm scope

[NDHunter]

Hey everyone, looking for some help. Anyone have a preference for either 40 or 50mm scopes? Obviously a 50mm will be better for really low light but is it worth it? I am looking at a Leupold vx3 CDS. Does it make much of a difference trying to look through the scope since it sits up higher on the barrel? Maybe it is a Ford vs. Chevy debate but I'd like to get some input from you guys if I could. Thanks!

[packer58]

Take a look at the Leupold VX-3L, it's contoured objective bell allows it to be mounted on low or medium rings depending on barrel contour, also you can have the CDS turret installed through Leupold's custom shop. With this set up you'll have the best of both worlds, very bright optics with the 50 mm objective and the lower mount. IMO

[bigshot]

I can see a big difference in low light between a 36mm and a 40mm scope, so I can imagine a 50mm will be that much brighter.
I own three Leupold VXIII with CDS on my hunting rifles and love them all. Two are the 3.5x10x40mm and the other is a 2.5x8x36mm. My next Leupold will probably be a VX-3L 4.5x14x50mm, also with CDS, because of its design it sits low on the rifle like a 40mm but with the brightness of a 50mm. I don't care for the feel of a regular 50mm scope or bigger, they don't seem to fit my shooting style.

[Bitterroot Bulls]

Well it really depends. Apparent brightness is a combination of factors, but the most important one is exit pupil (the little circle of light in the ocular lens). You can calculate your exit pupil: Objective diameter divided by magnification=exit pupil). Notice how when you turn down the magnification on your scope in low light the image gets brighter? So a 3-9X50 would appear brighter than a 3-9X40 at higher powers. The catch is the image doesn't appear much brighter once the exit pupil is larger than 7mm, because 7mm is as large as most people's eyes can dialate.

The 40mm objective scopes are nice in scopes of moderate (say 3-10) magnifications because they provide adequate exit pupils for bright images, and they faciliate a low mounting height, and the subsequent excellent cheek weld. Proper cheek weld is extremely important for precision shooting.

Large objectives are particularly usefull on high-magnification scopes, because they are necessary to get useable exit pupils for low light performance at high magnifications. A 50mm scope at 10x provides a very nice 5mm exit pupil, bu the 40mm scope still provides a perfectly suitable 4mm exit pupil (similar to the 4.2mm exit pupil of your typical 10X42 binocular). Once you get to 15x, the larger objective becomes more beneficial as the 50mm scope now has a useable 3.3mm pupil, while the 40mm scope has a dim 2.6mm exit pupil.

[jenbickel]

OMG Vince!! You're alive!
I say, go big or go home. Haha

[Ikeepitcold]

50mm is a must for me. With the high country long range hunting we do it makes the biggest difference to me. I have Leupold on 5 of my guns and all are 50mm.

[Shaun]

I swear by 50mm

[NDHunter]

OMG Vince!! You're alive!
I say, go big or go home. Haha

Yep I'm still alive and well! I've been busy trying to figure out where to hunt this fall.... How have you been?

I saw that you got yourself a new horse. Congrats! Does this mean that I can call you up the next time I am in Wyoming and need someone to pack out an animal?????????

Thanks to everyone for their responses. I'm still not sure which one I'll get but at least I have some good info to help me decide!

[jenbickel]

Hahaha!! Well that's a no brainer! You hunt Wyoming in the fall. Duh! And then when I am using my 50mm leupold scope and you're using your 40mm scope and I get the animal, you can watch me pack it out on my horse! Hahaha

[Colorado Cowboy]

I'm pretty much old school...reflects my age. My first scope was a new Weaver K3 I got for my 14th birthday, which in their time were great scopes. I now use Leupolds on everything I shoot. I have an older 6x on the same 03 sporterized Springfield that had the Weaver, to a Vari XIII 6 x 20 on my custom .220 Ackley Swift for varmints. I don't care for the 50mms because of the high mounts needed to clear the lens. I have always like to keep my cheek welded to the stock as low as possible...just more comfortable for me and my neck/shoulder relationship. I have not used the Leupold concept of the L series, but I imagine it would fit my criteria. But I have 10 Leupold scopes and it is not really feasible to change them as they all work fine for me.

The only thing that ever bothers me with scopes is the fade out you get from direct sunlight. I can live with that. I have never felt I needed more light gathering ability...when its dark, its dark and I quit hunting and head for camp!