ISO Performance at Low ISOs (ISO 100-800)
Here is the full image, showing which area of the image I cropped below:
Let’s take a look at how the Canon 5D Mark III performs at low ISOs. Here are some crops at ISO 100, 200, 400 and 800:
As expected, the Canon 5D Mark III produces beautifully rendered images at low ISO levels. The noise is practically non-existent, even at ISO 800.
High ISO Performance (ISO 1600-25600)
High ISO performance is a very important measure of DSLR sensor quality for low-light photography. Here is how the Canon 5D Mark III performs at high ISO levels between ISO 1600 and 6400:
As we increase ISO to 1600, a little bit of grain starts showing up in images. ISO 3200 adds noticeable grain throughout the image, but colors and details are well preserved.
Jumping to ISO 6400 adds significantly more noise, which is especially visible in the shadows. ISO 12800 is much worse than ISO 6400, which is now affecting shadow details and colors.
The maximum native ISO sensitivity of 25600 is clearly the limit – the amount of noise doubles and now we are seeing plenty of large grain throughout the image. There is a noticeable amount of detail and color loss here.
High ISO Performance “Boost” (ISO 51200-102400)
Canon 5D Mark III has two extra ISO “boost” levels – ISO 51200 and ISO 102400 for extreme situations. Take a look at these:
ISO 51200 is pretty useless, unless you heavily down-sample the image, whereas ISO 102400 is downright unacceptable for my taste, even for down-sampling purposes.
ISO Performance Summary
The Canon 5D Mark III produces excellent results at low ISOs. As you can see from the above, images are very clean from ISO 100 to 800 and it pretty much stays that way all the way to ISO 1600. Beyond ISO 1600 we start seeing noticeable noise that first starts affecting the shadow colors and details, then progressively gets worse at each ISO stop. Image quality quickly deteriorates starting from ISO 6400 and ISO 25600 is pretty much the limit of acceptable image quality. The boosted ISO levels 51200 and 102400 are useless in my opinion – they lack too much detail and colors bleed all over the image.
Overall, given the high-resolution 22.3 MP sensor, the Canon 5D Mark III produces excellent results, especially when the image is down-sampled to a smaller resolution.
It is hard to judge the performance of the Canon 5D Mark III without direct comparison against other professional cameras, which is why you should definitely check out the comparisons on the next page as well.
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