For me, it was mid 30's and I dropped the coin on top of the line Swarovski 56mm objective scope and Swarovski Bino's the same day, a bit of an ouch but I moved to SC and we could hunt an hour before sunrise to an hour after sunset and nothing I had would get me close. Just looking through them was completely eye opening, actually using them the next weekend in the woods was beyond eye-opening. I could spend hours in a climber glassing through the woods with no eye strain, the view was unreal and just standard german #4 reticle kept me in the game the entire hunting hours. All my leupold vari-x III scopes were gone within 2 years, kept my lesser scopes for stuff that didn't matter, top line Leupold was now total crap, replaced by swarovski/zeiss/S&B. My first clue my eyesight was going south I was about 45, feeling lazy and hunting out of a box stand on a power line because rain was in the forecast. I kept thinking there was sometihng out about 350 yards but convinced myself it was just wind blowing the weeds. My bino's were in my pack on the floor and I was too lazy to get off the comfortable chair and get them. I finally did, and there was a bunch of movement out there, several flocks of birds wandering in the weeds eating seeds on that bench about 350 yards away, all small birds. Just a year earlier, I could see sparrows clearly out there with my naked eye no problem. I started noticing other stuff and couldn't stand the "horrible" eyesight I discovered that year and went to the eye doctor. I was better than 20/20 in both eyes and the doctor questioned why I thought my eyesight sucked. It had been a good 10 years the last time I had my eyes checked before then, both eyes back then were way better than 20/10, so 20/20 sucked. I wish my eyes sucked that much now that I'm in my 60's.