Viewfinder / Autofocus

The EOS-1Ds has a very bright clear viewfinder which provides a huge field of view (full frame!), which, if you're used to digital SLR's with cropped viewfinders will come as a very pleasant surprise. Film photographers will feel right at home with the EOS-1Ds viewfinder. The EOS-1Ds has a very similar viewfinder to the EOS-1V apart from additional status information a better dioptre adjustment wheel and an eyepiece which protrudes 20 mm (0.8 in) from the rear of the camera (helps to keep your nose away from the LCD screen).

Below you can see a proportional comparison in the difference in field of view when looking through the EOS-1D viewfinder (1.3x field of view crop) and the EOS-1Ds viewfinder (no field of view crop). As you can see the full-frame sensor means that viewfinder view is considerably larger and brighter.

The diagrams show the AF ellipse and 45 focus points, the center spot as well as meter indicators (active points will glow red once AF is locked), buffer space indicator (88 JPEG) and camera status readout (horizontally along the bottom). Unlike the EOS-1D the EOS-1Ds always indicates 10 frames available in the buffer (before shooting) no matter what the ISO sensitivity.

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

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.

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

The EOS-1Ds uses the same 45-point area AF CMOS sensor used in the EOS-1D/1V, 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 EOS-1Ds 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 manual by permission.

Metering system / zones

Just like the EOS-1D/1V the 1Ds 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 over the viewfinder view image	21 zone meter sensor

Lens mount / Mirror / Shutter

The EOS-1Ds has the EF lens mount (identical to the EOS-1D/1V) and therefore supports all Canon EF type lenses. Because the EOS-1Ds 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. Note the size (diameter) of the Canon EF mount neck.

The mirror mechanism is the same as found on the EOS-1D/V, that means it also features the same Active Mirror Control system which uses a 'shock absorber' to soak up the bounce produced when the mirror flips back down to the normal position. This system means that 'mirror blackout' (the amount of time the viewfinder view is black) is just 87 ms.

White balance sensor

Just like the EOS-1D and previous the EOS-D2000 (but unlike the D30/D60 or other recent digital SLR's) the EOS-1Ds has an external white balance sensor mounted on the top right corner of the camera (from the front). This is used to provide 'additional information' to the camera's white balance system in combination with any reading measured by the main sensor. Canon have coined the name 'hybrid automatic white balance system'.