Canon 5DsR And Long Exposure Noise

In my last post, I presented one of my favorite images from my trip to Michigan's Upper Peninsula.  As much as I really like the image there is a problem with it.  It is a problem that is not visible to anyone looking at the image on the internet or at a small image size, but it is one that I suspect will limit my ability to make a very large print of the photograph as it is currently processed, which is something I was hoping to be able to do.

So what is this problem?  The answer is digital noise during the five minute long exposure. I will confess to being a bit of a 'pixel peeper', but really only am concerned about issues that would affect the final print. But before I discuss anything, allow me to show you what I mean.

Color and Luminance Noise In The Brightened Shadows

The portion of the image above is a 100% crop from the dark island/tree area of the photo AFTER noise reduction using Imagenomic Noiseware, and one can still see both color and luminance noise that is fairly marked. Now, it is true that I raised (brightened) the shadows a bit, which would tend to accentuate noise, so I will also show you a 100% crop from the straight out of camera image without brightening the shadows. Here the noise is minimal.

Pete's Lake Crop Right Out Of Camera

Perhaps I was expecting too much to be able to brighten the trees in order to to show some detail and color and perhaps the noise is purely related to the 5DsR's pixel pitch (small) and dynamic range as opposed to the length of the exposure.  That will take some experimentation on my part to figure out but, while that may well be the case, there is still luminance noise in the sky visible in this 100% crop after noise reduction:

Luminance Noise In Processed Sky

As one would expect, this brighter area is certainly less noisy than the shadows, but is still noisier than I would expect and noisier than I have seen in my shorter duration exposures.

So what does all this mean?  These are just early thoughts and so I am not really sure yet.  It will require some further experimentation to sort out the effects of long exposure vs the sensor's dynamic range.  I find this interesting, as it is something fellow photographer Cole Thompson has written about in a post entitled "5DSr Noise Issues".  

Of course, this doesn't necessarily mean I can't make a large print. The noise might not be visible in a moderate sized print. I could make the print with less processing and leave the shadows darker than I had in my processed version, which would hide the noise.  There are possibilities, those they are slightly different than was my vision for the final image.  Also, when doing long exposures I could expose to the right more in order to eliminate noise, assuming that the scene is not as contrasty as this.

View fullsize

Please don't get the wrong idea.  I am extraordinarily happy with my 5DsR as it is able to record amazing detail and color with ample pixels to crop as needed, but I suppose one has to obey the laws of physics and smaller pixels are going to deliver more noise.  Unless of course you have a Nikon. Or a Sony........only kidding. Sort of :)

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