45 I have thought about the 2.5 X8 X 36 how3 does it work in low light
Depends on the coating of the lenses. I've had a lot of experience in hunting situations. Quality of the glass is FAR more important than size of the objective.
what makes Leupold so exspensive
I will preface this by saying that I'm a scope snob. I've had cheap scopes fail on hunts when I had a chance at true trophy animals. I've had it with cheap scopes.
I was buying a scope for a Canada hunt. I was going to get a Swarovski (the best). Maybe overpriced, but I can afford it. Before I die I wanted one of the best.
So anyway, while looking at Swarovski I got talked into comparing against a Leupold VX-R. For clarity, the VX-R was very slightly clearer. I would never have believed it if I hadn't seen it myself. I've now used the VX-R on several hunts. My friend's Redfield would glare when pointed toward the setting sun. VX-R can be pointed directly at the sun with zero glare. Low light resolution is astounding. I could easily shoot when it's way past time that you could use irons.
In any event, IMO brand is not nearly as critical as price. Any good company's top of the line is going to be better than another's mid-line product, and significantly better than their low line product. In optics, you get what you pay for (unless you get a screaming deal on a discounted one).
With a cheap scope, you can get internal fogging on a rainy day. In poor light at high magnification, it will look like there is wax paper in front of the lens. The image is milky. In the show room, everything looks good in strong light at relatively close range.
If you get VX-III, Nikon Monarch, Burris Black Diamond, or B&L 4200 you'll be fine IMO.