As far as who's glass do they use, I don't know that it really matters. They could use glass from multiple glass manufactures and maybe even multiple lens manufactures. And they might do it or some of it in house too. Lots of optics companies keep things like this confidential.
Either way, they will only use the lenses that are up to the quality level they need for their optics. Then they (or a vendor) will apply their coatings to the lenses, to the spec they require. In the end all the lenses Swaro will use meet the spec requirements and I am sure are tested to make sure.
As far as are swaro good. They only make one level of scope. Which are the best they can make. They have multiple price points, but that is only because of the level of technology used in the scopes. The have the Z3 which is a 1 inch tube with 3x erector system, the Z5 which is 1" with 5x erector system, and the z6 wich is 30mm with 6x erector. They all use the same level of optics and are all excellent.
Edited by supertool73 - February/25/2016 at 12:14