Quality versus Resolution


Today’s Question: After reading an answer from you about sensor size it made me wonder about the Canon EOS 5DS R compared to the 1D X. Since they both have the same size sensor would the 1D X have a greater dynamic range and less noise since the pixels are larger? Or are they using a different sensor?

Tim’s Quick Answer: As a general rule, with two sensors of the same physical dimensions, the sensor with the lower resolution (larger individual pixel size) will provide higher dynamic range and lower noise levels. But that isn’t always the case, as demonstrated by the fact that 5DS R is capable of providing better performance at low ISO despite having a much higher resolution in a sensor of the same physical size as that of the 1D X.

More Detail: There are, of course, many factors that impact overall sensor performance. Therefore, general rules about what you can expect always need to be compared to actual real-world results produced under real-world circumstances.

The Canon 5DS R and Canon 1D X cameras have full frame sensors with the same overall dimensions. The 5DS R, however, features 50.6 megapixel resolution compared to the 18.1 megapixel resolution of the 1D X. That means the 5DS R has individual photosites (pixels) that are much smaller than those found on the sensor for the 1D X, which would reasonably cause you to assume that the 5DS R would offer lower dynamic range and higher noise levels compared to the 1D X.

The 5DS R is actually capable of producing higher dynamic range and lower noise levels compared to the 1D X, which is impressive (and perhaps a little unexpected). But you need to take a couple of additional details into account here.

First of all, the 5DS R was released more than three years after the 1D X. That’s a long time when we’re talking about advanced technology. While smaller individual pixels on a sensor generally translate into higher noise levels, it is also true that with technological advancements the noise performance of imaging sensors has improved over time.

In the specific case of these two cameras, it is also important to look at the testing data a little more closely. The results that I’ve seen show that the 5DS R does indeed perform better than the 1D X in many image quality respects, but only at relatively low ISO settings. About an ISO setting of somewhere around 400 or 800 ISO, the 1D X actually starts to perform better than the 5DS R.

So, again, general rules can be helpful in evaluating the overall landscape of digital cameras, and in providing a sense of what you can expect and what you might want to look out for. But it is also critically important to keep in mind that general rules are just general rules, and there are typically exceptions to every one of those rules. Also, as noted above, when a particular camera is described as “better” in some regard compared to another camera, that comparison is often an over-simplification of what actually detailed testing will reveal.

As always, it is therefore very important to go beyond the published specifications and general statements about a particular camera, and instead critically evaluate the specific performance numbers that are important to you based on your particular needs as a photographer.