Guys remember designing a work around isn't the way forward, There shouldn't be a need to have to work around a problem that basically should not exist in the first place, Im worried that the problem may start to become overshadowed by "what we all can do instead" I really am hoping for this tread to get heard, its a real problem and I do not believe for a moment it only happens in certain cameras (ie other 5D3's don't have this problem) its a problem with the 5D3 itself and needs to be addressed,
I would like to say thanks to everyone that has of course offered help in ideas making it easier while we wait for answers, but let us not forget the true problem exists and needs to be fixed,
good comments Louis. my only contribution, having read most of the threads on this topic is that there does appear to be two problems that are being confused with each other.
1. A problem where some cameras appear to perform better than others: Low light AF performance without flash or AF-assist. I see a lack of consistency in the test descriptions (standard, normalized EV is trivial to find and express but no one has done it) and no clear repeatable result saying that the AF system on a statistically significant number of 5D3s does not perform " in a way that is commensurate with the photo set-up, subject movement and required shutter speeds that would be associated with taking the picture in that amount of light, and when the camera is used as it has been marketed" RustyTheGeek has shown that his replacement 5D3 performs better than the one he originally purchased, for example. This to me is mfg QC.
2. A problem where none of the 5D3s described here perform well, and even some 1DX contributors have described similar behavior: Utilization of the AF-assist. Here the amount of ambient light shouldn't matter -- you should be able to walk into a dark closet, close the door, and take photos of a mouse running across the floor in pitch black darkeness. At reasonble subject distances, the AF system should use the assist beam! Frankly, given the information posted here I'm suspicious of a marriage problem between the AF system and the nature of the AF beam itself, its width pattern, pulse duty cycle, frequency; something. The common denominator here is the 61 point AF system shared (largely) between 1DX and 5D3. Its like the AF R&D team and the Speedlite R&D team don't know each other, or one doesn't consult the other, because something is fishy here. The AF system needs to be tweeked so that it can see and utilize the beam, for pete's sake. This is what makes me suspicous that Canon can fix this problem with a firmware update. THey just have gone dark side of the moon because they know the problem to exist and are planning their response to it.