Viewfinder (9.0)
Canon implemented a new viewfinder on the EOS 5D, covering 96% of the recorded frame in a 0.71x magnified perspective. The viewfinder has a 20mm eyepoint with a -3 to +1 dioptric adjustment. Some users may object to the 96% coverage, seeking the full 100% view provided by the 1Ds Mark II; however, those who have made a career shooting with 35mm bodies have likely become accustomed to the crop and have learned to work with it. Those who remain disenchanted with the 5D’s viewfinder coverage might at least take solace in the manner in which the view is altered. Unlike the 20D, which primarily took its 5% liberties from the top and left segments of the frame, the discrepancy in the 5D’s recorded frame is much more evenly dispersed. Files recorded with the EOS 5D will contain about an eighth of an inch more of the scene all around the frame, resulting in a far more accurate representation of the composition.
Thanks to the 5D’s full-frame sensor and larger prism, images displayed in the viewfinder will be much larger than those of cameras with cropped sensors. The image is considerably bigger and brighter than that on the cameras with APS-sized sensors, aiding in low light composition and providing a greater degree of perceivable detail. However, the expanded view does sacrifice space for text displays when compared to the viewing window of the cropped cameras; although, I presume this will be an acceptable tradeoff for the majority of users as Canon still manages to squeeze in a dense array of shooting information.
The display includes: a focus confirmation light, shutter speed, aperture, exposure level, AE lock, exposure compensation, AEB level, flash ready, red-eye reduction on, high-speed sync, flash exposure lock, FEB shooting, flash exposure compensation, insufficient flash warning in flash exposure lock, white balance correction, memory card full warning, memory card error, and no memory card indication. The autofocus points and spot metering zone are superimposed on the viewfinder image with the exception of the 6 supplemental AF points which are active, although only visible when viewed in the accompanying software. Canon added ISO ratings to the visible options, but this will only appear when the sensitivity is altered and its appearance causes all other shooting information to temporarily fall out of view.
Like Canon’s professional 1D series DSLRs, the 5D is also functional with multiple focusing screens to accommodate a variety of shooting situations. There are three Ee series screens that can be applied to the 5D’s viewfinder, although the Ec screens designed for the 1D series cameras are not compatible. The three focusing screens all contain random micro lens construction with varying elements, tailored to specific lens types. The 5D’s standard Ee-A screen and Ee-D grid-type focusing screen are optimized for f/5.6 lenses and slower, while the Ee-S screen offers more refined microlenses for f/2.8 lenses and faster. The interchangeable focusing screens speak of the 5D’s viability as a professional alternative. For various commercial uses, the ability to change focusing screens in invaluable, helping photographers maintain a proper workflow in varying lighting and types of shoots without having to rely on multiple bodies.
Viewfinder blackout is minimal; Canon approximates the lag to be roughly 145 ms at shutter speeds of 1/60 and faster.
LCD Screen (8.0)
The Canon 5D has a 2.5-inch, 230,000 pixel polysilicon TFT LCD screen that remains viewable from a range of angles. It is identical to the LCD that has been applied to the recent EOS 1D Mark II n and offers about twice the viewing area of the 1.8-inch LCD on the Canon 20D. In addition to the size advantage over the 20D’s screen, the display fixed to the back of the 5D offers roughly a 170 degree angle of view, which is far more than the 20D’s LCD, which solarizes at about 30 degrees off-center to the sides and about 5 degrees off-center vertically.
Some readers have offered responses claiming that the 20D's LCD is better – more saturated and full of contrast – but we don't find their argument too compelling. The 5D's display offers about twice the information and resolution that the 20D's does, along with an enlarged text font to make menu option far more legible. Besides, we’d expect most users purchasing a $3,000 DSLR to rely on the histogram to judge exposure rather than an LCD with varying brightness levels.
The EOS 5D offers 5 of these brightness levels to help maintain visibility in various situations. The LCD brightness adjustment is housed within the set-up portion of the camera menu. Once selected, a secondary screen comes up and displays a prerecorded frame in the center with a grayscale accompaniment along the left margin. This enables users to calibrate their camera monitor to the tonal values and illumination of the scene. The 5 available brightness levels are displayed in a horizontal line graph below at the bottom of the screen and are selected with the set button.
The reconfigured LCD on the EOS 5D and 1D Mark II n are larger than previous efforts and offer nearly twice the resolution. In general, this lack of LCD resolution is a pity since most serious digital shooters rely on their LCD to check focus and require a level of detail that most cannot stand up to. While the 
LCD on the 5D is definitely a step in the right direction, it too falls short of expectations. The screen does offer an impressive angle of view; however, when tested in bright conditions, the displayed image instantly washed out and became barely visible. Some under-performing LCDs contain a “sweet spot” of sorts, an obscure angle that retains visibility when the image fails to be adequate from straight on; however, we could not find one on the 5D. In low light, the screen stood up to the challenge, but its handling of bright daylight and strong studio lamps was incredibly disappointing.
There is also a rectangular informational LCD placed on the top of the 5D, to the right of the prism. The top panel LCD expands on the shooting information in the viewfinder and also includes an orange illumination lamp for reading settings in low light.
Flash (7.5)
The Canon 5D does not contain a built-in flash, which is a notable departure from the similarly-styled EOS 20D. Perhaps the absence signals the 5D's “professional” status – the top of the line 1D series lacks a built-in flash as well; however, this lack is more likely the result of engineering limitations brought on from the large prism. Nonetheless, the lack of a pop-up flash is a significant loss as the small in-camera units can often be handy for fill flash. Obviously users of the 5D can compensate for this loss by applying any EX-series Speedlite or compatible unit to the camera’s 5-pin hot shoe (all EX-series models are compatible). The EOS 5D offers E-TTL II autoflash with EX-Speedlites and contains a PC terminal for an additional wired connection; however, flashes applied via the PC terminal function like those connected with a single-pin hot shoe connection and will not be able to communicate exposure information.
The EOS 5D contains an x-sync of 1/200th of a second and a High-Speed Focal Plane Sync from 30 seconds to 1/8000th of a second. Flash exposure compensation is available in a +/-2 stop range, 
alterable in 1/3-stop increments. There is also a Flash Exposure lock function and Flash Exposure Bracketing setting available in +/- 3 stops in 1/3-stop increments.
As with most EOS models, when a dedicated 550EX or 580EX Speedlite is applied, multi-flash wireless TTL shooting is available and up to three groups of flashes can be controlled when ratios are manually set to create more dynamic, directional lighting. If varying illuminations are not needed, the 550EX or 580EX master can control as many slave units as are visible by the sensor.
Lens (9.75)
The Canon 5D is fitted with a metal Canon EF mount and is not sold with a kit lens. Canon's line of EF lenses is extensive, covering everything from fisheye and ultra wide angle to very long telephoto, with multiple choices of price and aperture at most popular focal lengths. Since the 5D contains a sensor equal in size to a 35mm frame, all applied EF lenses will retain their original optical perspective, enabling users to take full advantage of wide angle options. Canon's low-cost EF-S lenses are not compatible with the Canon 5D, so users considering a step up from the Canon Rebel XT or EOS 20D may need to purchase other compatible lens units.
Click here to see a list of all available Canon EF lenses
