The evolution of af speed & predictive af control – Canon EOS-1 User Manual

Page 7

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I. CAMERA FEATURES AND OPERATION

7

The EOS-1D and EOS-1Ds had the fastest AF systems available among EOS SLRs when

they were introduced, but the EOS-1D Mark II now has the most powerful AF system of

any EOS camera released to date (2004). The EOS-1D Mark II was the first Canon camera

to feature two dedicated CPUs for AF: one for detection and calculation, and another to

control lens drive. EOS-1 class cameras prior to the 1D Mark II used a single dedicated

CPU for all AF operations.

All EOS-1 class digital SLRs feature RISC (Reduced Instruction Set Computing)

processors so that multiple operations can be performed simultaneously. The extra

speed created through this method has made it possible to increase the power and

sophistication of the algorithms employed for predictive AF. Using an EF 300mm f/2.8L

IS USM lens and a fully charged battery pack, the original EOS-1 with Power Drive

Booster PB-E1 could track a subject moving at 300 kph/186 mph as close as 26

meters/85 ft. Using an EF 300mm f/2.8L IS USM lens and a fully charged battery pack,

an EOS-1D Mark II or EOS-1Ds Mark II can track a subject moving at 300 kph/186 mph

as close as 20 meters/66 ft.

10 feet

6 feet

250mph

185

125

62

30

3mph

6

20 feet

33 feet

66 feet

98 feet

400km/h

300

200

100

50

10

5km/h

1m

2m

3m

6m

10m

20m

30m

Predictive AI Servo AF Performance

How close can the camera track a moving subject with an EF300mm f/2.8L IS Lens

Subject Speed

EOS-1: 5 fps

(with Power Drive Booster E1)

EOS-1D Mark II: 8.5 fps

Subject Distance

The Evolution of AF Speed

& Predictive AF Control

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