Most significant of the issues is the autofocus (AF) issue; under certain conditions, (notably warm, bright, sunny days, conditions under which AF usually operates the best) photographer Rob Galbraith has reported poor AF performance. As of October 17, 2007, Canon technical representatives began stating the widely reported auto focus issue is suspected to be caused by an internal submirror assembly that requires replacement on most Cameras with serial numbers between 501001 and 546561 This correction has been made in production models dating to sometime shortly before the announcement of the fix. As of August 2008, some reviewers have continued to note some level of remaining problems with AF both in the EOS-1D Mark III and EOS-1Ds Mark III even after the hardware and firmware fixes noted by Canon. On March 3, 2009, Canon announced new firmware and a free AF recalibration for the 1D Mark III. Initial reports from owners who have received their camera back from the AF recalibration seem to be largely positive, although there are still some mixed results. This latest firmware available for the EOS-1D Mark III is version 1.3.2. The latest upgrades to the firmware for the Canon EOS-1D Mark III can be found on Canon's firmware download page.