Canon EOS 1Ds - Manual (Page 12)

Also, the second-generation, on-chip noise removal circuit and a
newly-developed noise reduction technology combine to remove
noise effectively. To achieve even less noise, the EOS-1Ds Mark III
has a new output amp that attains both high speed and low noise.
Low noise is also achieved with an improved manufacturing
process, optimized pixel amp, and optimized reading circuit.
Thanks to optimized photo diode construction and finer process-
ing, the photo diode can still accumulate enough light to function
exceptionally well. At low ISO speeds, the dynamic range is about
the same as that of the EOS-1Ds Mark II.
As with the EOS-1D Mark III, single-line, 8-channel parallel reading
is employed. With a low-noise, high-speed output amp, a continu-
ous shooting speed of approximately 5 fps is attained, even with
approximately 21.1 megapixels with which to contend.
The infrared, low-pass hybrid filter in front of the sensor consists
of an infrared-absorption glass (including multiple coatings to
reflect ultraviolet and infrared rays) and low-pass filter (phase
plate sandwiched by two single-crystal plates). Other than opti-
mization for the full-frame CMOS sensor, the specifications are the
same as for the EOS-1D Mark III.
The state-of-the-art AF sensor in the EOS-1Ds Mark III is shared with the EOS-1D Mark III.
The AI SERVO AF algorithm has been optimized to match the continuous shooting speed
of the EOS-1Ds Mark III, approximately 5 fps. Also, due to the full-frame CMOS sensor,
the Area AF coverage with respect to the viewfinder is slightly smaller than with the EOS-1D
Mark III. The AF speed and predictive AF performance are the
same as with the EOS-1D Mark III. All other AF-related specifi-
cations not mentioned here are also the same as the best-in-
class EOS-1D Mark III.
IV. DISCUSSION OF NEW AND IMPROVED FEATURES 12
Autofocus
Time
Low-pass filter
(Separates image in vertical direction)
Low-pass filter
(Separates image in horizontal direction)
Phaser layer
(Converts linear polarized
light into circular polarized light)
CMOS
sensor
Dichroic mirror
(Reflects infrared rays)
Infrared-absorbing glass
LPF Construction
Diagram of 8-channel
Signal Reading
: f/5.6 sensors
: f/2.8 sensors (Center AF point is f/4)
: Cross-type AF points : Assist points (Not user-selectable)
6.6
7.50
4.5
3.00
2.25
4.00
2.00
AF Sensor Configuration
AF Sensor