Metering And Exposure Control; Custom Functions - Canon EOS 1Ds Mark III White Paper

Having the same drive mechanism as the EOS-1D Mark III, the EOS-1Ds Mark III's maxi-
mum continuous shooting speed is 5 fps in both the One-Shot AF and AI SERVO AF
modes. This rate is achieved with 8-channel reading, DDR-SDRAM (twice the capacity of
the EOS-1Ds Mark II's), and Dual "DIGIC III" Image Processors. Continuous shooting
speed can also be adjusted with C.Fn III-16 [Continuous shooting speed] as follows:
High-speed continuous within 2 to 5 fps, and low-speed continuous within 1 to 4 fps.
Metering and The metering optics have the metering lens and 63-zone metering
Exposure Control sensor positioned at the rear of the pentaprism. The 19 AF points in
the Area AF optimally match the metering sensor's zones.
The same 4 metering modes as in the EOS-1D Mark III are provided.
Metering Sensor
Partial metering covers about 8.5% of the viewfinder area at the
center, and spot metering about 2.4% at the center.
Because the metering area within the viewfinder is smaller than that of the EOS-1D Mark III,
the algorithm has been optimized for the EOS-1Ds Mark III. However, the basic algorithm
is the same as the EOS-1D Mark III's.
Metering Zones
Evaluative/Center-weighted
Partial metering Spot metering
average metering
* C.Fn I -7-1 enables AF point-linked spot metering.
ISO bracketing is not provided in either the EOS-1Ds Mark III or the EOS-1D Mark III.
With the Ec-A, Ec-B, Ec-I, and Ec-L interchangeable focusing screens, only spot metering
outside the center and center-weighted average metering is possible. Since the prism
centers of these focusing screens are plainly transparent, an error will occur with evalua-
tive metering, partial, and center spot metering.

Custom Functions

The Custom Functions are the same as the EOS-1D Mark III's. The Custom Function
names, settings, numbers and so forth are the same. The only exceptions are C.Fn I-3
[Set ISO speed range], C.Fn I-8-2 [Safety shift: Enable (ISO speed)], C.Fn I-15-1 [Flash
sync. speed in Av mode: 1/250 sec.], and C.Fn III-16 [Continuous shooting speed]. Either
the setting values or control values have been changed to suit the EOS-1Ds Mark III's
specifications.
IV. DISCUSSION OF NEW AND IMPROVED FEATURES 17