articles/Sports/cricketmathstripodsnature-page2

On cricket, maths, tripods and nature - part 2 of 1 2 3 4 5 6 7 8

by Mike McNamee Published 01/12/2009

In those (say) 1,800 frames there may be 20 dismissals and of these we might assume 50% are from catches, leaving just 10 per match that are clean bowled, stumpings, lbws or run-outs. The maths then, is quite simple, only one frame every 180 is going to contain the bails flying in the air! If you then factor in a player obscuring your view of the stumps, this 'success' rate drops even lower.

This then is the problem facing the professional cricket photographer. They have to shoot every delivery, 'just in case'.

They also need more than one frame per delivery, for, if they time for ball-bat impact and the ball misses the bat, the second shot of the sequence may contain the bails in the air, a stumping or a vigorous appeal for a caught behind - all will make a good shot, most of the time.

The advantage then of cricket is that the player is almost stationary and does not move very far. The disadvantage is that he (or she by the way,

Let's do some more sums! The stumps are 22 yards apart. The ball is delivered by a quick bowler at a hand speed of something under 100mph - a more typical value would be 80mph, representing 120ft/s. The ball slows in the air to 100ft/s when it bounces; there it is further slowed to about 65ft/s when it has, typically, a further 13 feet to travel to reach the batsman (this distance varies from almost zero for a full toss to almost half of the pitch length for a bouncer).

The ball takes 0.48 seconds between leaving the bowler's hand and pitching, then a further 0.22 seconds to reach the wicket. The diagram shows a plot of the ball trajectory and the position of the ball is indicated assuming that the motor drive is activated as the ball leaves the bowler's hand. Four framing rates are shown, only two of which are actually achievable with current digital SLR cameras. Thus at 5fps (frames per second) it is quite easy to miss the action completely. Even at 10fps the ball would be imaged at first contact with the ground and then just before it passes over the stumps (or into the stumps).

• On cricket, maths, tripods and nature page 1
  
• On cricket, maths, tripods and nature page 2
  
• On cricket, maths, tripods and nature page 3
  
• On cricket, maths, tripods and nature page 4
  
• On cricket, maths, tripods and nature page 5
  
• On cricket, maths, tripods and nature page 6
  
• On cricket, maths, tripods and nature page 7
  
• On cricket, maths, tripods and nature page 8
  

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