6) Image Sensor
Without a doubt, the most important feature of a digital camera today is its image sensor. You could put the most advanced autofocus and metering systems with a boatload of great features into a camera, but at the end of the day, they are all more or less secondary – the sensor performance is still looked at first. Things like resolution, dynamic range, diffraction, color depth and ISO performance are all tightly related to the sensor and its physical size. When I talked about the D800 being “revolutionary”, I mostly referred to the phenomenal sensor technology Nikon incorporated into the camera.
The Nikon D800 features the highest resolution full-frame sensor produced to date by Nikon. With a pixel size of 4.8µ, it is comparable to the excellent sensor on the Nikon D7000, except it is physically more than twice bigger in size. Nikon tweaked the output of the sensor even more with a better image processing pipeline, giving us even better dynamic range and colors tones. As I have already pointed out earlier, folks at DXOMark made some scientific measurements of sensor performance on the D800 and they found it to beat all other sensors they have evaluated to date, including some high-end medium format cameras. The Nikon D800 topped all cameras in dynamic range, as can be seen below:
In terms of color depth, it came third, right after Phase One IQ180 and Phase One P65 Plus, which is also very impressive (considering that Nikon D7000 is 23rd on the list). But the biggest surprise for a lot of people was the high ISO performance of the Nikon D800 that DXOMark shows. Take a look at this ranking chart:
At first, it mind sound crazy that the D800 could have almost as good of ISO performance as the new Nikon D4, especially considering that the pixels on the D4 are much bigger in size. But as I have already explained at the very beginning of this article, the massive 36.3 MP resolution is what makes this score. When the 36.3 MP image is down-sampled to match the D4’s 16.2 MP image, the high ISO noise performance is greatly reduced. See the comparison page of this review to see the actual comparisons between the D800 and the D700 and you will see what I mean.
I do not think we will see a camera that will even remotely match the D800 sensor performance for the next couple of years at least. The Sony A99 will have the same sensor as on the D800, but I doubt its image quality will be the same for two main reasons. First, Nikon has a better image process pipeline than Sony (especially in dealing with noise at RAW level at high ISO levels). Second, Sony’s translucent mirror blocks 1/3 of a stop of light from reaching the sensor, which means that the A99 ISO output will have to be boosted further up, resulting in slightly noisier images.
Click here to download the above photograph in high resolution (8 MB JPEG).