Canon 6D and 5DMk3 Noise Comparison for High-ISO Long Exposures

Astrophotography enthusiast Don Marcotte wanted to find out whether the Canon 6D or Canon 5D Mark III was more suitable for his area of photography, so he pitted the two cameras against one another in a few noise tests at his local camera store. He simply shot long exposures without any light (the cap was on) in order to see how much noise would show up in the frame.

As you’re looking at the following images showing the results, keep in mind that this test was for a very specific purpose and might not be relevant to other types of photography. Marcotte tells us,

I was evaluating the 6D vs Mk III for a specific photographic application: nightscapes with the sky in the background. Even with super wide angle lenses, the stars will trail at 26 secs. But you need a lot of photons to capture the sky. So I wanted to find a very low noise camera that would give me what I needed at 15 secs and ISO 3200.

For this first comparison, Marcotte shot 15-second exposures with the two cameras in RAW mode with noise reduction turned off, converted the images to 16-bit TIFFs in Canon Digital Photo Professional, created 400x400px crops, and then boosted the gamma up to 3.0 in Photoshop CS5 in order to see how much noise is present:

Here’s the same test done, except the exposure time was increased to 30 seconds:

For a final test, Marcotte decided to pit the two newer cameras against his personal Canon 5D Mark II, which is modified for astrophotography. He used the same process as the two tests above and a 15-second exposure time:

Here’s the conclusion Marcotte came to, which he shared over at planet5D (they’ve published a lengthier writeup of this test):

The 6D is the clear winner at 15 and 30 seconds for ISO 3200 and 6400 […] I would expect that no one could detect a noise difference between the 6D and 5D3 for the vast majority of daylight photography. Only in low light conditions would a 6D deliver observably better results.

It’s interesting that the “entry-level” full-frame DSLR outperforms the higher-end one, but what’s crazier is how much the sensor in both cameras have improved since the 5D Mark II.

Update: DxOMark’s latest sensor tests of the three cameras seem to confirm Marcotte’s findings:

Image credits: Photographs by Don Marcotte and used with permission