While the Nikon D800 is a very capable camera, there was one feature that got photographers more excited than any other, its 36-million-pixel sensor. This put it on a par with medium format cameras and even now, over a year and a half after its launch, it is still the highest resolution small format DSLR available.
And when the Canon 5D Mark III was launched a month after the D800, many photographers scoffed at its paltry 22-million-pixel resolution. Some dismissed it out of hand without even considering other aspects of image quality or its superb handling characteristics.
Aim high
A key advantage of a good sensor with a high pixel count is that it can resolve plenty of detail. The D800 and its optical-low-pass-filterless friend the Nikon D800E make this very clear.
The often mentioned downside of having a very high pixel count is that the photoreceptors themselves have to be made smaller than on a sensor with a lower pixel count. This means that they receive less light and generate a smaller signal which needs greater amplification. As a result the images are noisier and it's more important to shoot at lower sensitivity settings.
There's also another drawback to a high pixel count that doesn't get mentioned quite so often. That is that the camera is more susceptible to image blurring from camerashake. Even tiny movements have a significant impact when the photosites are very small.
As a result we've found that if you're handholding the D800 you need to use a shutter speed of 1/125sec or faster to get images that are sharp at 100% on screen. In some instances this may mean that you need to push the sensitivity up a stop or two and accept that the image will be a bit noisier than you might have wished.
Meanwhile if you're using the camera on a tripod, you need to use a remote release and engage mirror lock-up or exposure delay to avoid shake from the mirror blurring the image.
Some may argue that these issues only come to light when you pixel peep, but if you're paying for a 36-miilion-pixel camera you expect to be able to get the full benefit of them.
Middle ground
As well helping to keep noise levels down, having a lower pixel count means that any tiny accidental camera movements are less significant, so the camera produces (smaller) images that look sharper at 100% on-screen.
With many cameras now topping the 20-million pixel mark we have started to use the word 'just' when describing sensors with 16 million pixels. It's a popular count for the Micro Four Thirds format, but we forgive it because it is a little restricted by its smaller sensor size, plus cameras like the Olympus OM-D E-M1 are very capable.
Traveling light
The Nikon Df is a comparatively small and light full-frame camera. It is weatherproof and designed to be used outside on treks and adventures. And while it can be used on a tripod, those who buy it to travel light are less likely to want carry a tripod, so it will probably be used handheld most of the time. Consequently, it needs to offer the ultimate in low light capability and noise control.
By plumping for a sensor and processing engine that is used in its top-of-the-line SLR, the much-respected D4, Nikon has given prospective owners of the Df a clear signal that it is a high quality and capable camera. It should also be a model that can be pushed to the limits of low-light shooting with a top expanded sensitivity setting of ISO 204,800.
In conclusion
There are plenty of valid reasons why the Nikon Df should have a sensor with 16 million pixels. But would most prospective owners like it to have a 24-million pixel sensor like the Nikon D610?
Probably.