It instead relies on the AF assist lamp built-into most Speedlite external flash units.įirst introduced on the Canon Rebel XTi, Canon's system-wide approach to reducing the impact of dust on the image sensor is also included on the Canon 5D Mark II. Canon normally uses the flash for AF assist on their DSLRs, but the 5D Mark II has no built-in flash. The Canon 5D Mark II does not provide an AF-assist illuminator built into the body. On the other hand, that wouldn't explain the fact that the 5D's single-point AF speed is lower than that of the 50D. If it's all the time one might think that this would slow the AF system somewhat, in exchange for it being faster and more accurate under fluorescent light sources. It's not clear whether the averaging of AF sensor readings goes on all the time, or only when the camera detects a particular type of lighting. The result is improved AF accuracy and speed when shooting under lighting conditions that could fool the AF systems found on earlier Canon and competitive models alike." In both the EOS 50D and EOS 5D Mark II, the type of lighting is taken into effect, and readings are averaged and processed with the help of the super-fast DIGIC 4 Image Processor. These tend to throw off the density measurements and therefore the accuracy of the AF calculations. But under fluorescent lighting and some other artificial lighting sources, a rapid, imperceptible flickering of the light occurs along with sudden color temperature shifts. Here’s how it works: during Phase Detection AF, the AF engine rapidly measures the density of horizontal and vertical details in a scene and the camera processor uses this data to determine where the sharpest edges and details are located. "Improved precision over previous AF systems stems from each camera’s ability to adjust for different light sources while calculating focusing distance. Here's Canon's explanation of the problem and its solution, taken from their EOS 50D and 5D Mark II White Paper: The problem can arise as the AF system evaluates the data coming from the AF sensor, flicker in the lighting that's imperceptible to the human eye can cause the AF sensor to misjudge the location of the sharpest details within the frame. Light source detection addresses the problems some (many?) AF systems have with artificial light sources that flicker. While still offering nine user-addressable autofocus points (one cross-type in the center) and six non-addressable assist points (with three center AF points sensitive to f/2.8 lenses), the 5D Mark II autofocus system does include the lens micro-adjustment (for up to 20 lenses), and light source detection functions we've seen on the company's other recent high-end digital SLRs, so there are autofocus improvements even if the sensor itself hasn't been overhauled. The autofocus sensor from the original Canon 5D has been carried over in the new 5D Mark II. Be sure to click on the Blur Index charts for an interactive look at how the lens performs across its range of apertures and zoom settings on both full-frame and APS-C bodies, as well as our reports on its chromatic aberration, vignetting, and distortion characteristics.ĪF sensor arrangement. To see more on this lens, visit our review on the 24-105mm IS lens by clicking here. It's priced at an average of $960 on its own, so the $3,499 suggested price of the kit reflects about $160 savings over buying them separately. On a full-frame body like the 5D Mark II, it's wider than the 18-55mm, performed very well in our tests on, and comes with image stabilization, a very worthwhile feature to have. The Canon EF 24-105mm f/4L IS lens that ships as part of the optional Canon 5D Mark II kit in the US has much better build quality than most kit lenses bundled with SLRs these days (such as the 18-55mm that shipped with the Canon Rebels), and has a longer zoom range as well. The full-frame sensor on the Canon 5D Mark II means there is no "crop factor" for this camera, or that the "focal length multiplier" is 1x, the same as 35mm film. EF-S lenses can't be used on full-frame Canon cameras, nor on their models with 1.3x crop factors, like the current EOS-1D Mark III. Designed with a smaller image circle (the area covered by the image on the film/sensor plane), EF-S lenses tend to be smaller and lighter than full-frame models with the same focal length and maximum aperture. The Canon 5D Mark II will work with pretty much any EF-mount lens ever made, however it is not compatible with the special EF-S lenses designed for cameras with APS-C size sensors. Canon 5D Mark II Optics Lens Compatibility
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