Viewfinder / Autofocus
The Mark III sports one of the largest viewfinders on the market and it shows; looking through the Mark III's eyepiece is an engulfing, immersive experience that serves as a stark reminder of how much we lost when we moved to crop-sensor SLRs.
In the diagram below you can see the AF ellipse and 45 focus points, plus the center metering spot. Active AF points glow red once AF is locked (depending on AF area mode). The buffer space indicator adjusts its estimate of space available depending on the selected ISO sensitivity.
|1||Metering mode||10||ISO speed indicator|
|2||Manual Exposure||11||ISO speed
Highlight tone priority display
FEB in progress
Exposure meter (manual exposure mode)
Flash exposure level
AF point selection
|14||Maximum burst in continuous mode
AF point selection
Memory card number
Flash exposure compensation
|8||White balance correction||17||Battery Level
In automatic AF point selection mode the camera will highlight (glowing red) the AF points which were used to measure AF distance (you can change the brightness using C.Fn III-13). On the right side of the viewfinder is the eyepiece shutter lever (not visible above), this allows you to blackout the viewfinder eyepiece to prevent stray light entering the camera during long or remotely triggered exposures.
Default display is indicated in bold.
Diagram reproduced from the EOS-1Ds Mark II manual with permission.
Auto Focus and metering
The EOS-1Ds Mark III uses a new 45-point AF sensor (the same one as used in the EOS-1D Mark III) that increases the number of cross-type sensors to 19 (the Mark II had 7) - plus 26 'assist' points (which cannot be selected).
|There are a total of 45 AF points. Those shown here in red are high sensitivity cross-type sensors that can detect both horizontally and vertically with lenses of F4 or faster.||You can restrict your choice of points to the outer (shown here in blue) or inner 9 (shown here in red) points - in both cases including the center point (shown here in yellow).|
As mentioned above you use C.Fn III-9 to split the 19 selectable cross-type AF points into one of two sets of 9 (8 outer plus center or 8 inner plus center) - or allow all 19 to be selectable (the default setting). As well as the usual 'quick dial' access to focus point selection the latest firmware allows you to use the new multi-controller to quickly switch focus points when the metering is active (without pressing the AF point selection button first). It would be nice to be able to select all the AF points (including the assist points), but you can't.
This is a huge improvement and speeds up focus point selection considerably. Pressing the multi controller in (like a button) pops the focus point back to center (or whatever you've set your 'home' point to be).
Lens mount / Mirror / Shutter
The EOS-1Ds Mark III has the EF lens mount (identical to the EOS-1D/1Ds Mark I and II) and therefore supports all Canon EF type lenses. Because the EOS-1Ds Mark III has a full-frame sensor it does not introduce any field of view crop. Thus a 16 - 35 mm lens on the EOS-1Ds provides a field of view identical to a 16 - 35 mm lens on an EOS film camera.
| C.Fn III-15 enables 'Mirror lockup' mode, in this mode the first press of the shutter release locks the mirror up, the second press opens and closes the shutter curtain (and thus takes the shot). This mode is especially useful for shooting long exposures or high magnification macros. New for the Mark III is the option to cancel the Mirror Lockup using the set button.|
| The Mark III now offers a slower, quieter mode called 'Silent Single Shooting'. This replaces the custom function that did the same thing on the Mark II.|