EOS 1D Mark III's Revised Sub-Mirror Gets Rid of "Most" AF Issues

Now that Canon has come up with a solution to the sub-mirror problem and has also released a firmware update for the EOS 1D Mark III, the question on everyone's lips (well, not quite everyone, just on lips of the pro photographers owing such model) is: how much good has it done?

Well, according to RobGalbraith's website, the flagship model 1D Mark III is no longer marred by the ubiquitous AF issue and the main reason for that is the revised sub-mirror mechanism. The improved AF performance is also the result of the 1.1.3 firmware version. Despite the obvious improvment, the author believes the performance does not match that of the previous model, the 1D Mark II N.

Here's what Rob Galbraith has to say: "Without question, the sub-mirror fix improves EOS-1D Mark III AI Servo autofocus: it eliminates the camera's big drop in autofocus accuracy when the mirror box gets warm or hot. Our experience is that it helps stabilize the autofocus performance so that the EOS-1D Mark III delivers about the same number of in-focus frames whether it's warm or cold."

The article goes on to say that the "firmware v1.1.3 ups the number of in-focus frames the camera captures too and is an important part of improving the camera's autofocus. It does increase the number of properly focused frames the camera snares when the light is bright and, compared to v1.1.0, noticeably improves the feel of the autofocus system."

The conclusion: "[...] in our view, there's more work to be done. In bright conditions, the EOS-1D Mark III still doesn't match the EOS-1D Mark II N".

As a quick reminder, four major problems were noticed: initial acquirement of focus in a multi-frame burst, subject tracking, focus shifting when the subject isn't moving and extremely quick focus shifting with a moving subject.

As mentioned above, these issues were related to the rising temperature inside the mirror box, which was rather strange since most cameras have difficulties achieving autofocus in dim lit environments and not during bright sunny days.

Apart from acknowledging the problem, Canon also released a new firmware update for the EOS 1D Mark III with an AF-related improvement.

As reported on November 29th, "version 1.1.3 will increase the transmission speed with high-speed SD cards and will correct some Spanish and Korean menu screens. More importantly, it will fix the issue of not being able to release the shutter. Canon explains that, depending on the timing at which the AF-ON button and shutter release button are pressed, the shutter could not be released. Last, but certainly not least, it will improve AF tracking in specific conditions. Apparently, version v.1.1.3 will improve tracking of low-contrast subjects."

Speaking of version 1.1.3, you can download it from Softpedia here.

For more detailed information and test images, visit the RobGalbraith website.