Scope Objective ?

I know this ones probably been addressed several times, but I need advice.

I have a Leupold Vari X III 3.5x10x50. I am thinking of putting the same in 2.5x8x36 on my Model 7.

What are the advantages of each. My buddy thinks I should just stick with the 50mm for light gathering purposes. Is it really that much of a difference?

Details like lens coatings and clarity of the glass are more important than objective size.

I use an old model Vari-XIII 2.5-8x36mm and have never had a problem shooting early in the morning or late in the day. A new model will be even better, Leupold has greatly improved their sorry glass and coatings over the past couple of years. They're getting it on the right track.

I went with the VXIII 3.5x10x50 on my Model 7. I know that is a big scope on a small rifle, however I usually use this gun when I'm hunting in thick cover....I needed all the light transmission possible so I went with the larger objective.

There are many who would say that you are just as well served by a 40mm. I don't know...never did a hardcore comparisson.

I suppose it's a confidence game.

You would be keeping the weight down a tad with the smaller scope. This may be a consideration for a walking gun. You may also consider one of the nice fixed power Leupolds in 4 or 6 power. I want one of these on a .30'06 that I'm hoping to get from a buddy. FXIII 6x42, matte, German #4.

I've got see through mounts and iron sights, so the biggest I can use is 40 anyway. Not sure if that helps you or not, though.

From what I've read, usable light through a scope or binocs has to do with a number of factors. good glass and coatings are a big plus. One of the factors is exit pupil. When your eye pupil is completely dialated its about 4mm. If you divide the bell diameter (50mm) by the maximum magnification (10) you get 5. Supposedly corresponding to a 5mm exit pupil from the ocular end of the scope. The scientists say an exit pupil larger than 4mm does deliver more light to your eye, but your eye can't really make use of it.

This really comes into play during twilight - not so much for varmint scopes and shooting in bright daylight.

So in theory, a 2-8x32 (all other things being equal like glass quality and coatings) will be just as bright as an 3.5-10x50 when light transmission becomes an important factor. You just won't get as much magnification - obviously.

If you look at good quality scopes and binocs they all adhere to this math. Objective diameter in mm / magnification will usually equal 4-5mm.
The big difference seems to be good construction, glass quality and coatings. Either one of those Vari-X III will serve you equally well.

Something else to consider.

I have a round face with big fat, chubby cheeks (what every woman desires!). I can use a large objective scope on high mounts because I can still get a cheek weld to the stock.

If you are one of those poor, deprived folks with a thin face a large objective may "pull" your cheek up off the stock and reduce you chances of accuracy.

Fit the gun, stock, scope mounts and size of scope to YOU. One size does not fit all.

I've read that any objective over about 40-42 is kinda wasted as a scope can only allow so much light through. That said, I've got a 3-9x50 Leupold on one rifle and a 2.8-10x44 Simmons Aetec on my other