Viewfinder / Autofocus

	There really is no comparison to the Mark II's full frame viewfinder view. If you've grown acustomed to cropped viewfinders (as in most other digital SLR's) then looking through this eyepiece is a real eye opener (pun). Big bright, wide, tall, there's something intangibly nice about getting back to a full view.

Below you can see a visual demonstration of the difference between the view provided by the EOS-1D Mark II (1.3x crop) and the EOS-1Ds Mark II (full frame).

EOS-1D viewfinder view (1.3x FOV crop)	EOS-1Ds viewfinder view (no FOV crop, big!)

In the diagram below you can see the AF ellipse and 45 focus points, 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.

In automatic AF point selection mode the camera will highlight (glowing red) the AF points which were used to measure AF distance. 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

CMOS Auto Focus sensor	Cross-type sensors (horizontal and vertical sensitive) only with lenses with max. aperture of F2.8 or faster

The EOS-1Ds Mark II uses the same 45-point area AF CMOS sensor used in the EOS-1D/1Ds, it measures 15 x 8 mm and is located just below the semitransparent mirror and receives the exact same image you see through the viewfinder.

All AF points are sensitive to horizontal detail, however for a lens with a maximum aperture of F2.8 or faster lens a vertical row of 7 points (as indicated in red in the diagram above, right) become sensitive to both horizontal and vertical detail, and the manual notes, are three times more sensitive than the normal horizontal sensors. Some other L lenses with maximum apertures of F4 or brighter make use of the center cross-type AF point.

Having 45 focusing points isn't just about being able to choose your focus area within the image it also means that focus tracking (AI Servo) can be much more effective (as the subject is more likely to be picked up by at least one AF point).

AF point selection modes

Automatic selection - in this mode the camera will automatically select (and indicates) the AF point(s) which have been used to calculate the focus distance. C.Fn 10 allows you to change or disable the method of focus point indication.	45 AF Point Manual selection - in this mode the main dial (top of camera) moves the AF point horizontally, sub command dial (rear) moves AF point vertically.
11 AF Point Manual selection - in this mode the main dial (top of camera) moves the AF point horizontally, sub command dial (rear) moves AF point vertically. C.Fn 13 - 1 or 2	9 AF Point Manual selection - same procedure as described in the other modes, the AF Assist button and sub command dial can be used to quickly select a peripheral point. C.Fn 13 - 3

Registered AF point

The Mark II has also has a 'registered AF point' feature, this allows you to store the position of a most used AF point (such as the center point) and have it activate when the AF Assist and AF Point buttons are pressed, this is extremely useful for quickly switching back to a default AF point.

Diagrams reproduced from the EOS-1Ds Mark II manual with permission.

Metering system / zones

The Mark II has a 21-zone evaluative metering system. This provides several metering modes: evaluative, partial, spot, center-weighted average, AF point-linked spot and Multi-spot metering (plus flash E-TTL and TTL). The diagram on the left, above shows how these areas equate to the portions of the viewfinder view and AF points, in AF point-linked spot metering mode one meter zone serves several AF points.

21 metering zones overlaid on the viewfinder view	21 zone metering sensor

Lens mount / Mirror / Shutter

The EOS-1Ds Mark II has the EF lens mount (identical to the EOS-1D/1Ds) and therefore supports all Canon EF type lenses. Because the EOS-1Ds Mark II 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.