I had a good older pair of Zeiss till and unfortunate accident,, but with Bobs help I was convinced to go back to them and I can say my new ones are just as good as my old ones were. they are a little expensive but I see they also make a cheaper line that has more Chinese labor and parts. I use mine daily, I was even thinking of going real high end, but the Zeiss is really all I need. I watch the wildlife out in the fields from on top of tank batteries and star watching at night.. none of this calculations matter as long as the optics re well made with the proper coatings. so never buy cheap and they will work! thanks again Bob Tc