Canon 5D Mark II Optics
Canon 5D Mark II Optics
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.
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. On a full-frame body like the 5D Mark II, it's wider than the 18-55mm, performed very well in our tests on SLRgear.com, and comes with image stabilization, a very worthwhile feature to have. 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. To see more on this lens, visit our SLRgear.com review on the 24-105mm IS lens by clicking here. 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.
The autofocus sensor from the original Canon 5D has been carried over in the new 5D Mark II. 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.
Light source detection addresses the problems some (many?) AF systems have with artificial light sources that flicker. 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. Here's Canon's explanation of the problem and its solution, taken from their EOS 50D and 5D Mark II White Paper:
"Improved precision over previous AF systems stems from each camera’s ability to adjust for different light sources while calculating focusing distance. 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. When found, the AF is locked on target. But under fluorescent lighting and some other artificial lighting sources, a rapid, imperceptible flickering of the light occurs along with sudden color temperature shifts. These tend to throw off the density measurements and therefore the accuracy of the AF calculations. 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. 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."
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. 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. 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.
The Canon 5D Mark II does not provide an AF-assist illuminator built into the body. Canon normally uses the flash for AF assist on their DSLRs, but the 5D Mark II has no built-in flash. It instead relies on the AF assist lamp built-into most Speedlite external flash units.
Dust Reduction Technology
First 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. From the beginning, every DSLR has offered a sensor-cleaning mode, in which the mirror is locked up and the shutter opened to permit the sensor to be cleaned with compressed air, a solvent-carrying swab or other means. As the market has matured and more DSLRs have found their way into the hands of novice users, it has become clear that some automated way of dealing with sensor cleaning is needed.
A key feature of Digital SLRs is the ability for the user to easily swap lenses. This expands creative options enormously, but every time a lens is removed, dust from the environment is free to enter the camera body. From there, it's only a matter of time before some of it makes its way to the surface of the sensor where it casts shadows that appear as dark blobs in your images. In truth, it's the anti-aliasing filter that collects dust, rather than the sensor itself, but common parlance refers to "sensor cleaning." For the sake of familiarity, we'll generally refer to sensor cleaning here, but will make mention of the anti-alias or low-pass filter as seems appropriate.
The principal approach other manufacturers have used to deal with dust has been to make the system self-cleaning, by rapidly vibrating either the anti-aliasing filter itself or a protective cover glass lying above it, to shake loose adhering dust particles. Once dislodged, a strip of sticky material at the bottom of the sensor cavity or mirror box catches and holds them. This approach was pioneered by Olympus, but has since been adopted by Canon, Nikon, Pentax, and Sony.
In typical fashion, Canon's camera engineers took a comprehensive look at the issue of sensor contamination, and came up with a multifaceted, system-wide approach to reducing the impact of dust on users' photographs.
Canon's approach uses a vibratory cleaning method as a primary part of the overall strategy, but they've introduced several refinements as well. Here's what they've done:
Shooting Priority: Shutter Button Overrides Cleaning Cycle
It's critical for a digital camera to power up and be able to capture the first shot quickly, to avoid missing the action when first starting up. Some cameras with integrated cleaning systems can take a second or two for the cleaning cycle to complete before they're ready to capture an image. To avoid this problem, the Canon 5D Mark II aborts its normal power-on cleaning cycle as soon as the user touches the shutter button. This insures that you won't miss a critical shot.
Special Shutter Coating/Construction
It turns out that only some of the dust that appears in DSLR images comes from outside the camera: As they age, normal wear and tear can make shutter curtains shed microscopic particles that eventually end up on the sensor. In the Canon 5D Mark II, Canon has carried forward a special shutter-curtain coating designed used in other recent models to greatly reduce the shedding of particles.
Along with the specially treated shutter, Canon has also begun using a different plastic in their DSLR body caps, one less prone to creating shavings that can drop into the mirror box.
Split Anti-Aliasing Filter
Rather than introducing a separate cover glass into the optical chain, Canon has split the Canon 5D Mark II'S anti-aliasing filter into two parts. One element sits right above the sensor, while the other is positioned further away. It's this outer element that's vibrated during the cleaning cycle.
In describing the technology, Canon notes that the outer anti-aliasing element is positioned further from the sensor surface (a millimeter or so) than is normally the case. This greater distance reduces the effect of any dust that does adhere, by making the shadow cast by each dust particle larger and softer-edged.
Previous models in Canon's SLR lineup used an anti-static coating on the anti-alias filter to make it harder for dust to gain a foothold in the first place. Canon developed a new fluorine-based coating for the 50D, which purportedly improves this dust resistance property, and this new coating has been used in the 5D Mark II as well. Dust particles frequently carry static charges, so the anti-static coating avoids one of the key mechanisms by which dust particles adhere.
Dust Delete Image Processing
No matter how good an automatic cleaning system, there are going to be some stubborn dust particles that it can't dislodge. To deal with these, the Canon 5D Mark II has the ability to shoot a dust reference photo, and then transfer that information to Canon's Digital Photo Professional software, which can use it to eliminate the shadows cast by dust particles on the images.
This sort of image processing to eliminate dust isn't an entirely new development, it's been a feature of Nikon's Capture software for some time. Canon's implementation has some additional wrinkles that make it somewhat more useful, though. Primary among these is that Canon's "Dust Delete" processing works for both JPEG and RAW format files. (Nikon's works only with RAW images.) This really expands the utility of the anti-dust processing, and makes it more accessible to amateur users who shoot exclusively or primarily in JPEG format.
Canon's anti-dust approach is also different in that the dust map ("Dust Delete data") that the software uses to perform its magic is stored in the headers of the JPEG or RAW files created by the camera. There's thus no need to keep track of a separate dust image file, the information is always available in the file headers, assuming you've actually performed the dust-mapping process. You can update the Dust Delete data any time you think the camera might have been exposed to dust, or after you've manually cleaned the sensor. The latest dust map is automatically incorporated into the EXIF headers of all JPEG images, or the headers of any RAW files from that point going forward. While we don't have any technical details on how the dust map is stored, Canon claims that the encoding scheme used for it is very efficient, so the dust map information adds very little to the file size.
The screenshots above show the steps in capturing a Dust Delete reference image. Starting in the upper left from Shooting Menu Screen 2, selecting Dust Delete Data produces a screen that shows when the last Dust Delete reference image was captured. Selecting OK on this screen initiates a cleaning cycle, after which the camera prompts you to take a picture of a blank white surface. (The camera automatically defocuses the lens and sets the aperture appropriately, to produce the best possible dust image.) The camera then processes this data, and reports whether it was successful or not. If the surface you used to capture the image wasn't sufficiently uniform, you'll get an error message, but if the image was good, you'll see the confirmation screen as shown above in step 6. The Dust Delete Data just generated will now be included in the headers of any JPEG or RAW images captured, until you decided to capture a new dust reference image.
We don't have any quantitative way of evaluating dust-removal systems, but based on Canon's description of it, their anti-dust technology does appear to go a step or two beyond anything else currently on the market, providing a more comprehensive solution to the problem of dust in DSLR images than we've seen to date.
Don't count on the anti-dust system to do everything, though.
Despite the many advances in Canon's anti-dust technology, though, we feel compelled to point out that we've thus far seen no anti-dust system that completely eliminates the need for sensor cleaning. Sooner or later, you're going to need to clean your sensor, so we strongly recommend purchasing a good-quality sensor cleaning kit right along with your DSLR. Automated anti-dust systems like Canon's will certainly help with some of the dust, typically the dust that the nylon brush-based cleaning systems can also handle. Inevitably, though, you'll eventually encounter dust that sticks to the sensor's cover glass tenaciously; dust that only a wet/dry cleaning approach can remove. We ourselves use and recommend products from Copper Hill, which we've found to be both highly effective and among the most reasonably priced on the market. Check out their Basic Kit or Basic Kit w/SensorKlear for complete, cost-effective solutions.
The Canon 5D Mark II is sold in the US as body only, or in a kit bundled with the Canon EF 24-105mm f/4L IS USM lens. The images below were shot with the 24-105mm lens.
Kit Lens Test Results
Good performance with the EF 24-105mm f/4L IS (Image Stabilized) kit lens.
|24mm @ f/8.0||105mm @ f/8.0|
The Canon 5D Mark II is offered with an EF 24-105mm f/4L IS USM kit lens, with an optical zoom range of ~4.4x, and a focal length that goes much wider than most kit lenses. (Most SLR kit lenses start at 18mm but are designed for sub-frame sensors only, translating to about 28mm after the crop factor is taken into account.) Details are reasonably sharp across most of the frame at 24mm, though corners are slightly soft, and moderate chromatic aberration is noticeable. Some corner shading ("vignetting") is also noticeable at wide angle. Results at full telephoto are similar with softness in the corners and again, moderate levels of chromatic aberration. Vignetting isn't as pronounced at full telephoto, but the pincushion distortion is quite noticeable in this shot, as the straight lines in the house cover a larger portion of the frame. We really liked this lens when we tested it for SLRgear a while back (see our Canon 24-105mm IS review for those details), and apart from the issues mentioned above, it seems to be up to the demands of a full-frame 21MP sensor, but just. All in all, the EF 24-105mm IS has above average performance for a kit lens, especially for one that goes so wide on a full-frame body, and the image stabilization will come in handy in hand-held, low-light situations.
A larger than average area (for an SLR kit lens), with somewhat soft detail.
|Standard Macro with
24-105mm IS Kit Lens
As with zoom performance, the Canon 5D Mark II's macro performance will depend entirely on the lens in use. However, with the 24-105mm IS kit lens set to 105mm, the 5D Mark II captured a larger than average size minimum area measuring 5.98 x 3.98 inches (152 x 101 millimeters). Detail was a little soft at the center, with strong blurring in the corners from field curvature of the lens. (Most lenses have some softening in the corners at macro distances.) You'll definitely want a dedicated macro lens, if you plan on much close-up shooting with the Canon 5D Mark II.
Very high barrel distortion at wide angle, slightly higher than average pincushion at telephoto with the 24-105mm IS kit lens.
|Barrel distortion at 24mm is 1.4 percent|
|Pincushion at 105mm is 0.3 percent|
The Canon 5D Mark II's 24-105mm IS kit lens produced about 1.4 percent barrel distortion at wide-angle, which is much higher than average among the cameras we've tested, and quite noticeable. Unfortunately, this is a fairly common trait in higher ratio, wide angle SLR lenses, and it's harder to control on full-frame lenses than those made for cameras with sub-frame sensors. At the telephoto end, the 0.3 percent pincushion distortion is a little higher than average, and also noticeable in some shots. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).
Moderate and bright at both wide-angle and telephoto with the 24-105mm IS kit lens.
|Wide: Moderate and bright,
top left @ 200 percent
|Wide: Moderate and bright,
top right @ 200 percent
|Tele: Moderate and bright,
top left @200 percent
|Tele: Moderate and bright,
top right @200 percent
Chromatic aberration in the corners with the Canon 5D Mark II's 24-105mm kit lens is quite evident at the 24mm setting. It's less distinguished by its width (6-7 pixels) and more by its brightness. At 105mm telephoto, this distortion is almost as noticeable. Keep in mind that higher resolution sensors will tend to show more lateral CA than lower resolution ones. This is because the same amount of fringing spans more pixels, so CA appears worse when viewing at 100% than the same lens on a lower megapixel body. That said, though, the CA from the 24-105mm is plainly visible in the corners of 8x10 inch prints made from the Canon 5D Mark II's images. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)
Moderate blurring in the corners of the frame at both zoom settings with the kit lens.
|24mm @ f/4:
Soft in the corners (upper right).
|24mm @ f/4:
Sharper at center.
|105mm @ f/4:
Soft in the corners (lower right).
|105mm @ f/4:
Sharper at center.
The Canon 5D Mark II's 24-105mm IS kit lens produced moderately soft corners in a few shots, at both wide-angle and telephoto settings. There is also quite a bit of corner shading (or "vignetting") as you can see from the darker corner crops. Keep in mind these are crops from images taken with the lens "wide open", at f/4, and that corner sharpness and shading generally improve when the lens is stopped-down from its maximum aperture. Also, keep in mind that the crops above were taken with the 5D Mark II's Peripheral Illumination Correction disabled; see the section following for the results of this very effective in-camera adjustment.
Moderately high corner shading, but Peripheral Illumination Correction is quite effective.
|24mm @ f/4 with PIC Off||24mm @ f/4 with PIC On|
|105mm @ f/4 with PIC Off||105mm @ f/4 with PIC On|
As mentioned previously, the Canon 5D Mark II's 24-105mm IS kit lens suffers from quite a bit of corner shading or "vignetting". The 5D Mark II has a feature to address this issue though, something Canon calls "Peripheral Illumination Correction". As you can see from the above images, it is very effective at correcting corner shading in JPEGs. The supplied Digital Photo Professional software can apply the same correction to RAW files. The 5D Mark II contains peripheral illumination correction data for about 25 lenses, and you can register data for other Canon lenses using the Canon EOS utility software. Because the system requires correction data to be registered, third-party lenses are not officially supported.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Canon EOS 5D Mark II Photo Gallery .
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