The only ziess scopes I have any experience with is the lower grade and the swarovskis i have looked threw (never shot with one) were fairly old. These must be the reasons but I still love my Night Force
I have two 5.5-22x50(one on a 7 rsaum and the other on a 7rum) I have looked threw some swaro's and a few zeiss scopes and I think the nightforce gathers light much better and is just as clear. And they are made in the USA.