There is an interesting video on youtube (user Saika) [via P5D]. It compares two movies both shot with ISO 12800, one with the 5D2 and the other with the 5D3. You can view the videos side by side for an easy comparison.
There is visibly less noise in the movie shot with the 5D3. Click here to see a still taken from the video:
What do you think? Is the performance of the EOS 5D Mark III better? There is less noise, no discussion, but to me it looks as if the 5D2 maintains more details. It seems that the noise reduction algorithm on the 5D3 (at least at ISO 12800) does its job (heavily) at the expense of details. Click here to read the original post on P5D.
A more technical analysis of the 5D3 noise reduction algorithm can be read on dptnt.com. They downloaded dpreviews’ sample pics and did a in-depth analysis. The question they pose is
Did Canon improve the sensor ISO noise performance or did Canon improve their noise reduction algorithm in image processor?
Well, good question! Lets go on:
Examining the images at 100% reveals that the fine details indeed disappear when ISO is increased. It is safe to say the camera applied significant amount of NR to reduce the appearance of the noise but the question is how much and what is the true performance of the sensor. Without RAW files, we cannot know. But there is a way we can get some idea: the file size vs. ISO.
And here comes the point. I can’t show the graphs here, but you can see them on the original post. They conclude that
You can clearly see a step-down in file size at ISO 800. At ISO 12800, the file size increase from ISO 6400 is small compared to the file size increase from ISO 3200 to ISO 6400. It appears the image processor in Canon EOS 5D Mark III applies different levels of noise reduction at different ISO levels.
And finally that
The image engine inside Canon EOS 5D Mark III does a good job. There are definitely loss of the details when viewed at 100% but the loss mostly occurs at fine detailed area which may not be an issue depending on the output size and media.
Crops of the original images are available (click on the ISO value) at ISO 100, 1600 and 6400. Have a look and judge by yourself.
You may also want to have a look to my constantly updated 5D3 info page with lots of sample pics and movies, technical info, hands-on reviews and previews, world-wide pre-order options, and more (click here).