Re: nightforce iam new to them
I currently own the 3.5x15x56 NXS. You will not go wrong with the larger magnification, but it depends on where you are gonna shoot.
In AZ, where I shoot, mirage is a big deal all the time. Anything above 15 power and the image gets washed out. If you are comparing apples to apples (Hensoldt vs. F1), you must be looking at a FFP scope and if that is the case, and it is only available in the 3.5x15x50. If you dont care if it is FFP or SFP you can go with the higher magnification.
Seeing as how you are shooting a semi-auto (gas system), I dont think you will need anything over the 15 power anyway, unless your looking for the tacticool factor. You will have more maneuverability with the 15 power scope.
When it comes to NF or any other high end brand, the glass is all better than what you expect. With that being said, in my opinion, the glass in the USO, S&B and yes, the Zeiss is better than the NF. Even though, I would not trade my NF for another scope right now or ever. I might buy another scope later, but the NF will outlast my gun, and probably me. I cant say that about other scopes in the same category. And the glass on the NF is still amazing!
You cant go wrong with them for the money!
Good Luck
-Nate