You may need to re-do your homework, then...
I'm still on the fence. I shoot several jobs in the fall for which the Mark III should be able to provide a faster shutter speed and lower noise than my N can.
Regardless of what the camera will be able to do: DO YOU
absolutely need such speeds or not? In my case, most of the work we require the EF 24-105 f/4L IS. But this is an f/4 lens, which imposes on us the need to stay around ISO400-ISO800 when going indoors for non-sports customer jobs (lots of shadows and lost of bright things). The 1DMKII-N performs admirably well at these speeds, but, if we could get ISO800 at current ISO400-500 noise levels, I would not even think twice, since my job will definitely benefit, as well as the true-to-live look of final images (ISO800 @f/4, with slow shutter speeds such as 1/25s-1/30s with IS on gives pretty good chances for excellent non-moving indoor captures and portraits, while still using only ONE zoom!) Here, we will go to the 1DMKIII. The ISO800 samples posted on
www.imaging-resource.com are
UNBELIEVABLE. I simply have no words for them.
The thing that I'm trying to overcome is the notion that a better camera will make my pictures that much better.
Why are you trying to overcome this if, in reality, it is TRUE!? If the photogrpaher behind stays equally good (between two bodies) and one of the bodies open-up possibilities that were not in the range of the other one... guess what: you will be able to get better images, or simply images you could not get really right with the older body. The ISO variables, AF sytem (19-cross points), the 61-area metering, the highglights priority mode, etc., all come into play here. And we have not even yet mentioned extra resolution, or live-view, or 225grs less weight, etc.
A secondary question is even if the IQ is better will my clients know or care.
If they do not care, is because *you* are not doing your job into putting such benefits in the
prints. It requires that you truly extract the juice of the cam, the software, the post-processing (when required), etc. Our customers do notice the tonality depth, color density, dimensionality, color-fidelity and ultra-vivid (and clean) look of our images, and, not only that, they
get used to it and
notice when it is absent, though.
Most of my work is Web posting, contributions to magazines and 8x10 prints.
Here, the most important thing for you is if the extra ISO sensitivity will allow you to FREEZE/CAPTURE moments that you will otherwise blur with the 1D MKII/N or you could not pull so cleanly/sharply. For the rest, no need to upgrade if this is what you do.
How much different would a Mark III have made and would the customers have noticed or cared?
They care for what
you are able to put on the paper, visibly and tangibly. A blur-free, clean, sharp, well exposed (under-adverse conditions) image is something you should be able to put in paper, if your shooting circumstances/needs call for those items, though.
Good luck!