good question,

I have 40 mm objectives on all of my rifles. I went with this particular objective size for several reasons. One, I had grown up using my dad's Leupold's with the same objective size and I never had an incident where I felt a bigger objective would have gathered more light allowing me to shoot in a darker situation.
Secondly, by going with a 40 mm rather than a 50 mm, I was able to mount my scopes lower, which is very important to me. For one, this helps with a better cheek weld and more consistent hold/view through the scope. And secondly, the lower the scope is mounted, the closer it is to the bore, which reduces the affects of rifle cant, and as you know, a few degrees of cant at 800 of 1000 yards makes a big difference. The third reason I went with a 40 mm objective is I did not feel the extra money I'd spend on 50 mm objective was worth it considering the reasons given above. I could take that extra money and put it towards something else and not feel like I am handicapping myself with a 40 mm scope. A 50 mm objective scope would nice, I do admit, but I am very content with my 40 mm objectives and have no plans on changing any of my scopes to 50 mm objectives. Hope this is sort of what you were looking for.

Kind regards,

BB25

I prefer the 33mm objective lens because it gives all the light-gathering power the human eye can use, with its 6mm exit pupil, in magnifications up to 5+ power.
If I wanted to use the full 7 power, I would need an objective lens of 42 mm to realize the full light-gathering potential.
The ultra large objective lenses merely enable the shooter to use his full magnifiction range at low light conditons, which is only very rarely necessry or desirable. He could achieve the maximum benefit but simply reducing his magnifiction a bit.

99explorer,

I thought about simply listing all of the variables there are when it comes to long range shooting but thought even a list would be overkill. I did elevation, temperature because they have drastic affects at long range and threw the coriolis in as well because it has a subtle affect and is often overlooked but it still affects bullet flight. Cant is also important, I've not done the math yet but for a scope that's 2" center to center above the bore, I've head 1 degree of cant can affect bullet impact a half minute vertically and horizontally at 1000 yards. But as I said, haven't done the math for myself. I just am very careful to watch my level on my rifle.

Never spent much time considering the objective size when buying a scope. Unless it's one of those Leupold's with the divot out of the bottom, I've never really worried about it.
I'm just trying to kill deer.

Bubba

I use only 40's, but I do like the Leupold VX-3L with it's divot allowing the 50mm to be mounted at the same height as a standard scope with a 36mm objective. The VX-L Will be my next scope, these old eyes need all the help they can get.

http://www.chuckhawks.com/leupold_VX-L.htm

To lower the height of a mounted VX-L scope, Leupold has taken the simple expedient of grinding away a small curved section at the bottom of the objective lens and shaping the objective bell to match. The bottom of the new objective bell has a concave, rather than a convex, curve.

The visual effect is as if someone took a bite out of the bottom of the objective. The scope no longer sits perched above the barrel. Instead, when the scope is mounted low and over bore on a rifle, the barrel passes through this new "cut out" in the bottom of the objective bell. (See the photo at the top of this article.) It is a "Columbus and the egg" type of solution; so simple that the rest of us never thought of it.

I prefer the 50mm as I believe that allows shooting a little earlier in the morning a little later in the evening. The 50mm lens gather more light and should give a brighter image. ye, they are more bulky and a tad more expesive than the 40 mm lens but I feel the lightgathering adavantage out weighs the extra cost cost.

I vary depending on the use. I use a 50mm on my primary short range (out to 500 yards) hunting rifle. That objective definitely gives me at least 1/2 hour extra hunting time over my 40mm objective due to its noticeably improved light gathering. Since I am shooting at great big targets (like deer), the effect of cant doesn't get much consideration.

I like smaller objectives though for ease of use in carrying and putting in gun cases and for a better look. For most other shooting and for long range (1000 yards+) I use the 40MM objective for exactly what the well informed bb25 has described above. I shoot those rifles in good light and don't have low light concerns.
I also occassioinally use cheap scopes for some rifles and find that I can use 30-35mm tubes and 55mm+ objectives to get great light/resolution and minimal parallax for short range (out to 500 yard) target shooting at 20x or larger magnification. In using these for target shooting, I can control the cant in my bipod setup. I've only shot a few antelope with these big lens but they hit just fine, about the same as anything else, they are just heavy to lug around.

Most of my scoped rifles wear 40mm or 33mm Leupold's but I have a Burris with a 44mm and a Sightron with a 42mm that to me fall in the same class. I do not care for the bulk, cost, and lack of feng shui of the "Hubble" objectives, which I don't need. JMO

Dakotaman

You said above, "my primary short range (out to 500 yards) hunting rifle."

Really? You consider 400-500 yards "short range"?

You have been watching too much "Best of the West" infomercial shows on the hunting channel! LMAO! Either that or you have been listening to the long range bullshooters on here too much!

I believe Dakota is more than capable at 400-500 yards to call it whatever he pleases. Check out some of his targets in his photos, very impressive. Sub 2" group at 600 yards is no easy task, I've not shot a group that good. To all his own, and WA Mtn, this is a great example of where the definition on where "long range" starts is hard to agree upon.

Cheers

bb25

Target photos? Got a photo of the certified range to the target? I can shoot holes in a target at any range and post that too. Whatever.

ishawooa

DakotaMan never kilt no elk...

I think most people that are buying big objectives just don't understand how optics work.

A 50-56mm objective doesn't have some sort of magic light gathering ability. It just allows the exit pupil to continue to be a more acceptable size at higher magnifications. At the really high magnifications, you would need a ridiculously huge objective to match the performance of a 1-6X36 in low light.