I recently received my 1Dx3, having upgraded from a 1Dx2, and have been putting it through the tests. The following are my opinions from use. No photos, as this isn't a full in-depth review.
AF - my first impression was that it's a lot better. It snaps on quickly and does an excellent job tracking subjects. Since I'm a wildlife photographer, I tried the auto mode. It did a fair job, but I'm going to switch to the other modes (mostly 2 and 3) because it doesn't do the best job with birds that are at rest, then suddenly take off. Mode 3 in the past has worked well for that. I also found that my keeper rate wasn't dramatically better than what I achieved with my 1Dx2. Yeah, it feels better, but the results aren't dramatic.
High ISO - from a comparison with images of similar subjects, it appears to be about the same
Dynamic range - I live in the Pacific Northwest, so ISO 100 is mostly a myth for wildlife. Perhaps at that level there's a DR improvement, but I found it to be roughly the same as the 1Dx2 in the situations I use.
AF point selector - This is pretty cool, but IMHO not worth $6500
Silent shutter - It's more silent than the 1Dx2 and not nearly as annoying. Fps is noticeably higher.
Note that AF through LiveView isn't practical for me, since I always shoot handheld. I simply don't have the ability to track a bird in flight handheld with the back LCD. I do use LiveView for landscapes, but this is not intended to be a landscape camera. I don't use a gimbal because I constantly change positions + subjects. I've shot this way for a number of years and am used to it.
Overall this isn't a bad camera. I haven't found anything really wrong with it, but I just don't see the value over the 1Dx2. I'll give it another day or two of use to see if I change my mind, but right now I'm leaning toward returning it and sticking with the 1Dx2. If the other reviews are correct that AF is awesome with LiveView, then I expect their upcoming mirrorless bodies to be what I need.
Just to be clear, no I'm not going to Sony. I still like Canon and am very excited about the R5 and eventually the R1 + the lens variety is top notch. For my uses, though, the 1Dx3 just doesn't provide much to justify the cost.
AF - my first impression was that it's a lot better. It snaps on quickly and does an excellent job tracking subjects. Since I'm a wildlife photographer, I tried the auto mode. It did a fair job, but I'm going to switch to the other modes (mostly 2 and 3) because it doesn't do the best job with birds that are at rest, then suddenly take off. Mode 3 in the past has worked well for that. I also found that my keeper rate wasn't dramatically better than what I achieved with my 1Dx2. Yeah, it feels better, but the results aren't dramatic.
High ISO - from a comparison with images of similar subjects, it appears to be about the same
Dynamic range - I live in the Pacific Northwest, so ISO 100 is mostly a myth for wildlife. Perhaps at that level there's a DR improvement, but I found it to be roughly the same as the 1Dx2 in the situations I use.
AF point selector - This is pretty cool, but IMHO not worth $6500
Silent shutter - It's more silent than the 1Dx2 and not nearly as annoying. Fps is noticeably higher.
Note that AF through LiveView isn't practical for me, since I always shoot handheld. I simply don't have the ability to track a bird in flight handheld with the back LCD. I do use LiveView for landscapes, but this is not intended to be a landscape camera. I don't use a gimbal because I constantly change positions + subjects. I've shot this way for a number of years and am used to it.
Overall this isn't a bad camera. I haven't found anything really wrong with it, but I just don't see the value over the 1Dx2. I'll give it another day or two of use to see if I change my mind, but right now I'm leaning toward returning it and sticking with the 1Dx2. If the other reviews are correct that AF is awesome with LiveView, then I expect their upcoming mirrorless bodies to be what I need.
Just to be clear, no I'm not going to Sony. I still like Canon and am very excited about the R5 and eventually the R1 + the lens variety is top notch. For my uses, though, the 1Dx3 just doesn't provide much to justify the cost.