Lenses of the 1970s and 1980s had good distance scales and depth of field markings that provided fast, easy, and accurate depth of field settings. It was a totally manual operation with no auto focus, but it worked. If set to f 11, the 1970s vintage lens shown here would have a depth of field from just under 2 feet to infinity. Easy, huh?
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Canon’s implementation of “Depth of Field AE” mode on cameras like the EOS 1n, EOS 3, EOS 1V, and EOS 1Ds is nearly perfect for the critical photographer, and it can be used in several different ways. In the configuration I use, I simply auto focus on the near point, auto focus on the far point, and press the same button again to set the proper hyperfocal distance. I then set the aperture a stop or so smaller than the camera suggests, allowing for larger prints and any small errors that might exist. Canon's lenses have distance scales with very few distance markings and no depth of field scale. With Canon's depth mode making use of the precise auto focus mechanism, these scales don't matter. 
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Canon’s simplified implementation of depth mode on the EOS 10D is lousy by comparison. On this camera the near and far points must simultaneously line up with two of the camera’s seven focusing points. You have to press a button only once, but sometimes have to go through contortions rotating the camera so the near and far points you want line up with two focusing points. Then the camera sometimes finds two different objects that line up with two different focusing points. It’s maddening and slow, but it can be made to work most of the time. 
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This brings us to the Canon EOS 1D Mark II, which no depth mode at all. It works together with Canon’s lenses that have no depth of field markings and distance scales so sparsely marked that hyperfocal charts can barely be used. If you want both near and distant objects in focus with the EOS 1D Mark II, you must peer into a dark viewfinder while the lens is stopped down and guess whether the shadowy forms are critically focused. This camera is one of the most sophisticated photographic devices ever built, yet it provides no good way to let photographers perform one of the most basic functions in photography. Why Canon chose to omit their very effective “Depth of Field AE” mode from this high-end camera is mind boggling.
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Canon, what were you thinking?
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Happy focusing!