Half-Ball and the Natural Angle
Why half-ball is so important?
Half-ball shots are essential to Billiards and are very easy to play, especially compared with potting. A good Billiards player will hardly ever miss a half-ball long loser off a ball on the middle spot (from the D). Now compare this to a pot from the same position - even the top professional snooker players miss these! So Billiards players have a big advantage here, once they learn the half-ball stroke.
Where to aim
If you play without side and point your tip through the centre of the cue ball to the extreme edge of the object ball, this will give a 'true' half-ball. However, the shot is easier to play if you aim a fraction thicker than this, (aim to just inside the extreme edge of the object ball. The THICK HALF-BALL is the benchmark for which all half-ball shots are defined and gives a NATURAL ANGLE.
The greatest angle possible
The term natural angle is used to describe the angle that the cue ball takes after contact with the object ball, when a half-ball contact is made. This natural angle is the greatest angle at which a rolling cue ball can ever leave the object ball, assuming there is no stun or side. If the shot is made either thicker or thinner than half-ball, the cue ball will not throw as wide.
A massive margin for error!
There is a massive latitude for the half-ball shot. Take for example the standard long loser with the white on the middle spot. If you divide the top side cushion into quarters, then roughly speaking if you can direct the white to within the third quarter of the side cushion, you will get the long loser. (The actual area on the side cushion that must be hit is between 15 inches (381 mm) to 34 inches (864 mm) from the face of the top cushion). If you compare this to a pot, it is clear to see that the long loser has more than ten times the margin for error for contacting the object ball!
If you are slightly inaccurate you will still get the half-ball shot because hitting fractionally either side of the thick half-ball will still give the same natural angle for the cue ball. This latitude in contact makes thick half-ball shots much easier than any other shot - you can be slightly 'out' but still get the shot. You may want to begin by trying a true half-ball, because the aim point is easy to define. However, in this case you won't have much leeway if you hit the ball thin and you may miss the shot.
Billiards TheoryAim Point
The aim point for the thick half-ball is 1.6mm inside the extreme outer edge (exactly 1/16 of an inch).
The natural angle of the CUE BALL is approximately 34°. The deflection of the OBJECT BALL from a thick half-ball contact is approximately 28° and for a true half-ball contact is approximately 30°.