A new RAW processor has been released by Adobe that allows me to open up the CR2 and NEF files from each of the brands to compare (my previous comparisons were between JPG renditions which seemed to open up so much debate). I chose the Imaging-resource samples of ISO 50 shot with no noise reduction applied to them or any sharpening. The D800 is a production sample, while the 5Dmk3 was still pre-production. Regardless of what production state, this comparison should not be affected by that fact (unless the sensor was further redesigned from the pre-production, which I would not expect to be the case).
In this comparison, it will demonstrate whether the massive increase in resolution in the D800 is truly warranted. An increase that has been much talked about by many photographic circles including the cost of massive 207 MB 16 bit files to work with. The increase is almost three folds more than the previous generation of Nikon cameras, and is almost 1/3 more than the 5Dmk3. However at what cost does the increase of resolution in terms of image quality? The biggest issues here are diffractive limits which is a property of physics that limits high density sensors from using smaller apertures like F/8 and up. The D800 most certainly provides more details with a 36MP sensor, or does it?
|Mouse over to compare to the D800 Samples|
|Mouse Over to see the D800 400% comparison (Bicubic Linear increase)|
Some might question whether if the alternate Nikon D800E would give any improvements? A good question, but also something I also questioned last year in my article (click to read article) on replacing the AA filter from your cameras with a neutral piece of glass. In my findings I found very little if no benefit of replacing the AA filter.
I don't know if I can draw any real conclusion here, but if making a choice to pick one over the other based on MP is what you're hoping to find, then I can say that there is no benefit of one over the other. However this does come with a minor but. Diffraction is rearing it's ugly head already on the D800 examples, and no lack of AA filter or any software intervention can correct for that. Is the 5Dmk3 worth paying $500 more than the D800? Only you can make that call, however in this comparison, I would say that the MP advantage in terms of resolution does not give any more details than what they marketed to be so. For landscape photographers that shoot at F/11 or more, I would caution the idea of using a higher MP camera like the Nikon D800 for the idea that you can make larger prints. The diffractive limits will certainly negate any advantage, and as the posted examples will show, there are no net benefits of one over the other.
In terms of medium format cameras which in some circles Nikon users believe will best, this is certainly not true. Medium format film still out resolves this sensor, but it does get closer, at least in terms of the lower 30MP digital sensors of medium format, this is at least an alternative to going to medium format for those studio shooters that are considering that path.
I noticed another interesting thing but want to add this as a sidebar comment. It almost looks like the 5Dmk3 images are actually sharper. I would certainly treat this with a grain of salt. This could simply be a focusing error from the initial tests. You can see purple fringing on the Canon samples and Green fringing on the Nikon samples. However it doesn't negate the fact that when the Canon samples were upsampled that there were little if no difference. I did not focus on the sharpness issues in my article as I'm uncertain if this is a slight focusing error. The other thing to note is that the MTF of the Sigma 70 macro is an extremely sharp lens, so this should negate any debate on whether or not this lens can resolve for sensors at this density.
Another question is if there are real benefits to more MP? Well in terms of High ISO it actually is a huge net advantage. Here's where high MP really wins out. Because of the 1/3 more details, noise is actually smaller. Even though the new 5DmkIII has better high ISO performance than the D800, when noise reduction is applied, there is more details in the D800. However who'd benefit from this the most would be very specialized or left to those portrait photographers that produce rather large prints, or maybe those rare cases of those that do astro photography where High ISO and detail is really important. But hitting the ball back into the Canon court, they know full well that when you increase density of a sensor it also means more noise even if the noise is smaller. This also affects the dynamic range where blacks get lost in all of that noise.