Burris, bushnell, bausch & lomb, & kowa are the most popular. However, contact gil hebard guns @ 1-309-289-2700 and request a product catalog. The bushnell spacemaster zoom is $275.00. The burris landmark zoom is $175.00 & the burris compact is $94.50
btw: I own a redfield spotting scope made in the early 1960's & it is fantastic for range use. It is big, heavy, & looks like crap, but you talk about a great view through the lenses !!!!
Just don't try to go cheap---your sore eyes will tell you if you messed up !!!