Cutting off a tiny snippet of bud leaf isnt going to kill your plant. Sure if you go snip some huge thing it can hurt it by using up energy to repair instead. You dont need a very big thing at all.

We had the same problem and couldn't find the smaller scope. Built a little stand to set the scope next to the bud, turned off the fans for a few minutes, and just did it that way. Worked great and was easy to move around. It was a camera tripod with some quick duct tape modifications.

I harvest with trichomes. Most everyone will tell yuo this is the way to go. Some people say 50% cloudy, 25% cloudy... As long as they arent all cloudy or not cloudy at all, your in the green pretty much. For me, smoking on a sunny day outdoors instead of inside gets me more high then smoking something that was 25% amber or 60% amber trichromes. But, not that I use it for the harvest but I use it for a quick gauge, the percentage of hairs that have died and changed color tends to correspond pretty well with trichrome maturity. When its about 75%-80% changed color, is usually when my trichromes are "around" 50% cloudy.