If it's a fun shoot you will be allowed a rangefinder and I would recommend someone have one in your group, but check with the club to be sure. They will also have stakes for different classes set at different yardages. It's fun to shoot the farthest stakes where most of your shots at deer will be in the 30 to 40 yard range. Try to guess the yardage first and then range it to see how close you are at estimating.