I own Tract, Leupold and NF. You will have to be lucky to find a used NF at $500. Not impossible, but not likely. My Tract has been nice. Good glass for the money, BUT I wasn't impressed with its high magnification clarity. I find myself backing off a bit for a better picture (sounds goofy, I know). If you are going to set it and forget it, go with Leupold. For $500, you can find some good used loopy deals. Years ago, I had a Vortex PST, 4-16x50. I would use my VX-3i to spot the holes in the paper when I couldn't see them with the Vortex.......sold the PST shortly thereafter as there were better options in that price range. Take a look at Zeiss. Should be able to get their Conquest line used at your price,