I can't speak for the 800 or 900 . But I now own a 1200 CRF and in bright mid day light it is sometimes a task to range deer or antelope on flat ground at 800 yards. Now in the morning or evening light or if you are ranging game on a hillside where the beam can reflect off of rocks and trees around the game, I can range over 1000 yards easy. Hope this helps..
Jeff