My standard scope is a Leopold 3-9x40. Many use a 1.5-6x20mm on a African style rifle? if they are seeking a low power scope wouldn't they be better using a 2-7x33 and gaining more light gathering from a larger scope? I don't understand the reason for the small objective opening?

Helps with fitting the scope on longer actions. the 1.5 also offer a wider field of view on its lowest setting which many would prefer over any light gathering ability. Lastly is eye relief, usually, get a bit more on the lower power variables.

I recently screwed myself over trying to follow your same logic. I had a vx3i 1.5-5, I thought a 2-7 would be better. Did a bunch of horse trading to finally end up with a vx2 2-7 and it wouldn’t fit in my 375HH, tried extended bases and still no go. Ended up with a Nikon monarch 1-4 which is a nice scope but a step down from what I had. Pretty lame experience all around lol.

I like the 4.5x14 or 3.5x10’s, but I’m not trying to put one on a 375.

Objective size has little to do with light gathering ability.
Higher end glass and coatings of a 1.5-5x20 VX-3 will be brighter than a 2-7x33 VX-2.

Plus wider FOV and better mounting options as mentioned above.

Plus, scope brightness is generally less important on an African rifle than most American hunters would assume. It can be important in some situations, but not like when hunting whitetails, especially on public land.

Not sure I believe this assertion; certainly has not been the case for my eyes.

Yeah Utah, I call BS on that too. I hunt till the very last legal second. I'll take my VX2 w/33 mm objective and you other guys can have the 20mm objective. Bad part about that though is the 20mm guys will have to put their guns down at 5:45pm and I'll keep hunting till 6:05pm. powdr

Scopes do not gather light, they transmit it.

Objective size directly correlates to the size of the exit pupil in relation to the magnification.

The 1.5-5x20 will have a smaller exit pupil on 5X than the 2-7x33 scope will at 7x. (4mm and 4.7mm respectively)

The 2-7x33 at 5x will have a 6.6mm exit pupil, so it will be capable of more light to the eye, meaning more light available.

There is far more to the equation than simply coatings.

Many hunters will go to 50mm from 40mm for more light gathering capabilities. I would think that downsizing to 20mm would greatly reduce the light gathering capability of this scope.

I am not concerned about hunting situations just comparing the facts of objective lens diameter in relationship to light gathering capabilities?

You eyes can only process so much light. You can throw all the light down the tube that you want. I've always understand the larger objectives only truly make a difference on really high magnifications... like 16 on up. Too many quality 40mm scopes out there that can have you shooting well before or after legal shooting times if you see fit to do so.

It is my understanding European stand hunters are shooting in light conditions that most of us North American hunters do not shoot in. Which is shown by the huge objective lenses that are so popular with Euro hunters and becoming increasingly more popular with hunters on this side of the pond. I do believe glass quality and reticle style are the most important features for a scopes usefulness with objective bell size coming in 3rd. But, the bigger the bell with equal glass, the more light will be transmitted and may allow a higher power setting and still transmit all the light our eye balls are capable of using

I hunted with a Leupold Vari X 1.5-5x20mm and a Duplex reticle for 12 years on my .338 Winny. Much of it was late evening moose hunting where shots were well under 200 yards and killed moose.

I still keep a VX3 version with a German #4 reticle on hand for use on my Larue AR and have not found a faster scope with more eye relief.

Every since it's arrival that little scope has been the one scope I most often saw on rifles used for DG in Africa. Combined with the German #4 or a Post/Duplex reticle it will easily work for lung/shoulder shots at 300 yards. From the bench I found very little difference in group size at 100 yards when using that small scope compared to larger scopes.

My current "low light" moose and bear scope that is on my .338 Winny is a VX-R 3-9x40 with the wonderful Fire Dot 4 reticle and Kenton industries turrets. The glass quality on the scope is plenty good enough for me, but if Leupold had offered the same reticle in the 2-10x42 VX5-HD scope I would not of sold it to a friend.

Last fall in the evening, I had the usual moose passing through the yard and at 50 yards I had no problem seeing the kill area on a moose with any of my scopes. My 60 year old Weaver 4 power was the worst, but with the big Post reticle I could of still made the shot.

It depends on the magnification you're using as well. If you're at such a low magnification that either a 20mm or 33mm objective is providing an exit pupil larger than 7mm then the extra light isn't getting past your iris to your retina anyway.

I own both scopes on hunting rifles and would rather have the 1.5-5 at last light, or if I hunted at night.

You'll learn Jack...it'll just take the right buck. powdr