The Canon EOS 5D Mark II is one of the most highly regarded DSLRs of all time, so the 22.3-million-pixel Mark III upgrade has a great deal to live up to. How will it fare?
Image: With no space between the gapless microlenses of the EOS 5D Mark III, more of the light entering the camera will be directed onto the photodiodes
With Sony offering a 24.3-million-pixel, APS-C-sized sensor in its Alpha 77, and Nikon’s D800 boasting a 36.1-million-pixel, full-frame unit, it may seem a little strange that the resolution of the EOS 5D Mark III has only been increased 1.2 million pixels from its predecessor.
Canon clearly believes that this level of resolution is perfectly adequate for enthusiast and professional photographers, and has instead worked to produce a more efficient sensor.
One way in which Canon has done this is through the use of the same gapless microlens technology found in the EOS-1D X. Microlenses focus the light that reaches a camera’s imaging sensor into the photodiodes. If there are no gaps between the lenses, far more light will reach the photodiodes and be converted to an electrical signal.
Even small increases in the amount of light reaching the photodiodes can improve dynamic range in shadow areas, effectively improving the camera’s performance in low-light conditions. This also helps to cut down on image noise.
The sensor has been further improved by adding a noise-reduction circuit in the image sensor. This circuit should help even before the raw data is produced, at which point noise is further reduced.
The camera’s sensitivity of ISO 100-25,600 is expandable to ISO 50-102,400. This is a 2EV increase at the top end of the camera sensitivity spectrum compared to the ISO 50-25,600 expanded sensitivity range of the EOS 5D Mark II.
The increased sensitivity range is down to a 14-bit Canon Digic 5+ processor, which is responsible for controlling all the 5D Mark III’s circuitry.
Combined with the fast DDR-SDRAM memory, the camera is able to shoot at 6fps, which is 2.1fps faster than the 5D Mark II. When using a UDMA 7-compatible CompactFlash card, the memory buffer allows up to 18 raw images to be shot in a single burst, or up to 16,000 JPEGs. A second memory card socket for SD cards is also present on the 5D Mark III (although not on its predecessor), and this allows video footage to be saved to one space and stills to another.
Two of the other major new features have already been mentioned: one is the 63-zone metering system, which is also used in the EOS 7D; and the other is by far the biggest improvement – a completely overhauled AF system (more about this later).