Here is some help for judging distance. Take the distance for what you are shooting at. Look at it and find the mildle than find the middle of the section close to you.at this piont it should be real eazy to figger out how far the 2nd split is. than just times 4 in you head.

youhere / / <= target here
/ /
/ /= = this is 5 yards so you would be shooting 20 yards to the target This will put you close to the distance.It will not be right on the butten but close.It is not to hard to do up to about 10 yards so 40 is not to hard.

Good luck
Charles Bradford