There's certainly plenty to consider with the EOS-1D Mark II. The camera might look very similar to its predecessor outwardly, but a lot has been changed under the skin... Most obviously, a new 8.2 megapixel CMOS sensor in place of the EOS-1D's 4.15 megapixel CCD means significantly more resolution - a maximum image size of 3504 x 2336 pixels instead of 2464 x 1648. New microlenses that have less space between them allow increased light gathering and better sensitivity - reflected in an ISO range that runs from 100 to 1600 by default, despite the increased resolution. This range can be increased to ISO 50 to 3200 courtesy of a custom function. As for image noise, Canon says this will be lower than the existing EOS-1Ds model; the Mark II aims to remove fixed-pattern and random noise, and uses dark frame subtraction on exposures over one second. The lower power consumption of the CMOS sensor, repositioning of circuitry to reduce interference, and shortening of flexible wiring between circuit boards all do their part as well.

Given the major resolution increase, it is extremely impressive that Canon has managed to not just maintain the speed and burst depth of the camera, but actually increase it as compared to the EOS-1D to 20 RAW or 40 JPEG frames at 8.5 frames per second. The speed comes courtesy of the new CMOS sensor coupled with a doubling of the amount of buffer memory, the choice of DDR-SDRAM for that buffer memory (a first for a digital camera), and the new DIGIC II processor (now a single board instead of two) which reads 8 channels of data off the sensor at a time instead of the usual 2 channels. Burst speed isn't the only place the EOS-1D Mark II is set to impress. Canon claims a startup time of 0.5 seconds (almost twice as fast as the 1D's 0.9 seconds), 40 - 55ms shutter release lag and 87ms viewfinder blackout. Focusing speed should be improved as well, thanks to two new 32-bit RISC processors (a 33MHz AF CPU and and a 32MHz camera CPU) which together allow a doubling of the number of focusing measurements that can be made in any specific amount of time. The dual processors also allow operations to be executed in parallel to improve speed - for example, in One-Shot AF mode, AF processing, SI display and aperture stop-down are executed in parallel with lens driving and mirror flip-up. Active mirror control, which works via a hook on the back of the mirror to hold it in place when it flips down, reduces mirror bounce and viewfinder blackout time, letting the camera resume focusing and metering measurements more quickly.

Write speeds are also apparently much improved - depending on the flash card used, a whopping 5.0MB/second as compared to 3.2MB/second on the 1D, and just under 2MB/second on the 1Ds. Another benefit of the new DIGIC II processor is said to be improved white balance performance. The sharp-eyed amongst you will have noticed that the EOS-1D's external white balance sensor for the hybrid white balance system is gone - Canon apparently feeling that they can now do better just by working from the sensor data. The company says white balance accuracy from the sensor will particularly be improved at lower color temperatures, in tungsten and fluorescent lighting. Ten white balance modes ranging from full automatic to direct input of a specific color temperature (in degrees Kelvin) are available, and a new white balance compensation function simulates color conversion / color compensation filters with 9 levels of adjustment and the ability to set blue/amber and magenta/green bias in combination. The white balance compensation function can also be used in concert with the overhauled white balance bracketing feature, which now requires only a single shot to provide three white-balance bracketed images.

Canon has totally overhauled its E-TTL flash metering system for the EOS-1D Mark II, and E-TTL II should fix perhaps the biggest bugbear with the old system. The original E-TTL worked on the assumption that the autofocus point would cover the subject - a logical assumption that was usually the case, but was thrown off when you prefocused and then reframed the image. E-TTL II works to correct this problem as follows: (description courtesy of Canon)

"In the new algorithm, ambient light is measured when the shutter button is pressed. Next, a pre-flash is fired and the metering sensor takes readings at the central 17 metering zones. The ambient and pre-flash readings are compared. The metering areas having a small difference are selected as the flash exposure metering areas. (Areas with very big differences between ambient and pre-flash readings are excluded or down weighted because they are assumed to contain a highly reflective object or that the subject is not in that part of the frame. The algorithm avoids chronic underexposure problems in such situations.) These readings are weighted, averaged and compared with the ambient light reading, and the main flash output is then set and stored in memory. E-TTL II weights and averages the flash metering for the subject and all other objects at the same distance as the subject. Even if the subject’s position, reflectance or size changes, the flash output will not change radically. The flash exposure will be highly accurate and stable. Most EF lenses provide distance information, and this data is also considered in determining if there is a highly reflective object, once again lessening the chance of underexposure"

Another area that's seen major change is the image storage of the new camera. Most obviously, where the EOS-1D only supported CompactFlash Type-I or Type-II cards and Microdrives, the EOS-1D Mark II adds a second card slot for Secure Digital cards. There's also support for FAT32 filesystems, removing the 2GB limitation and allowing use of much larger flash cards. The Mark II also adds much greater control over JPEG files, with an impressive 4 JPEG resolution settings, and 10 compression levels at each resolution. A new RAW file format called Canon RAW 2nd Edition (.CR2) stores more metadata than past RAW files, which can be accessed by Adobe's Photoshop CS. When viewing images on camera, you can now access an RGB histogram - useful because it allows you to see if colors are clipping in just one channel but not in others. Camera settings can be saved and loaded into other Mark II's - something that could be particularly useful if you ever have to return the camera for a repair. The Mark II also offers support for IPTC captioning, Exif 2.21 and DCF v2.0., and a data loss protection feature ensures images aren't lost if you accidentally open the flash card door whilst images are still being written to flash - just close the door again, and the write process will continue.

Some hardware changes to the EOS-1D Mark II include a new higher-res LCD display (the same 2.0 inch size, but at 230,000 pixels almost twice the resolution), an NTSC / PAL video out connection for photographers who need to review their images on a larger screen, a four-pin Firewire port in place of the previous six-pin port (with apparently a 100% increase in transfer speed as compared to the EOS-1D) and a USB port intended for direct connection to compatible printers. The card slot knob has been redesigned for easier use when wearing gloves, and a number of changes have been made to increase the durability of the camera (a shutter rated at 200,000 cycles instead of 150,000; a stronger flash accessory shoe; improved dust and water-proofing; and a machined aluminum die cast mirror box).

Finally, Canon is introducing new software alongside the EOS-1D Mark II. Canon Digital Photo Professional is said to be five to six times faster than the File Viewer utility was at rendering RAW files, and offers features like the ability to save and recall image adjustments for reuse on other images, a side by side or split image comparison function, and more. An optional ($749) accessory Data Verification Kit DVK-E2 will permit verification of original untampered image data, allowing the EOS-1D Mark II to be used in legal proceedings and other applications where the ability to confirm that images haven't been altered in any way is crucial.

This is by no means a complete list of the changes between the EOS-1D and the EOS-1D Mark II, but it serves to highlight some of the more significant changes. On paper at least, this looks to be a truly impressive camera that raises the bar to a new level - and it will be interesting to see how Canon's competitors can respond (and in what time-frame). The EOS-1D had the advantage of a long period during which it was really unrivalled, and if Canon can achieve the same feat with Mark II, a lot of pros may be forced to consider switching allegiance even if they have a large collection of glass for a competing brand. With the EOS-1D Mark II set to ship in April at a cost of $4499 (fully $1500 below the price originally announced when the EOS-1D was launched), this is one camera we're definitely looking forward to reviewing!

Following is a detailed comparison of the EOS-1D Mark II with its predecessor, and Nikon's D2H. Full specifications for the Mark II can be found in yesterday's news item , along with numerous product photos...

* Note that the burst depth is perhaps a little misleading - the 8.2 megapixel images from the Mark II being so much larger than those from the 4.1 megapixel D2H, they obviously require a lot more buffer memory and processing power to deal with. That the Mark II comes so close to matching the much lower resolution D2H's rated burst depth is testament to the impressive speed of Canon's new model...