Hi, I am quite new to this forum. I have been using my Fujinon 10X70 binocular for quite a while and found that its light gathering ability is good. Recently, some salesman introduced me spotting scope and I was quite amazed that it can easily zoom 20X. As the salesman told me the diameter is 80mm, is it correct that it is comparable to a 20X80 binocular?
Yes and no. ;-) With binoculars you are using two eyes, so there is a sense (at least in binocular astronomy) that you can see stars that are fainter than what you can see through a same diameter (and magnification) telescope.