I wasn't able to figure out the absolute max in that situation. I ranged rocks easily at just under 1700 yards on a sunny day mid-day last week. I ranged trees at over 1800 yards at the same time. The next ridge over where I could have tried more trees was much further out and I couldn't get a range.
Other guys had a G7 BR2, Swarovski EL Range, Leupold rangefinder and none of them could range the rocks or trees mentioned above.