The Nikon D800 effectively functions as Nikon’s flagship camera. While the Nikon D4 is technically the “top” camera in the Nikon range (DxOMark side by side comparison), the D800 has the highest megapixel count and is widely regarded as being the best all-round model in the range.
Given its price-point, the natural competitor is the Canon EOS 5D Mark III, but this “only” sports 22.3megapixels in comparison to the Nikon D800’s 36megapixels. Once the Nikon D800 was tested in the labs, it became clear that with a whole range of lenses, the Nikon D800 was out-performing every other camera tested (5D Mark III lens results are not yet available)
With the increase in megapixel counts on camera sensors, there is ever more stress placed on the optical system that begins with the lens. If the sensor is able to resolve more detail, then any imperfections in the lens are more obvious. Fitting a poor quality lens to a high quality camera sensor is therefore actually a false economy because you do not maximize the capability of the camera sensor.
To give you an idea of which lenses are best on a given camera, you can look at the lens-camera efficiency. That is the ratio between the pixel count of the camera and P-Mpix score. This ratio depends on three factors - the sensor performance, the quality of the anti-aliasing filter in front of the sensor and the quality of the lens. By looking at the efficiency of a series of lenses on the same sensor, it is possible to compare the relative quality of each lens in terms of how it performs compared to its peers.
Taking this comparison a stage further, it is also possible to compare the efficiency score between different cameras using the same lens. With the megapixel race still on-going between the different camera manufacturers, providing an efficient lens, in other words one that offers the best quality for a given pixel count is ever more of a challenge for the lens manufacturers.
As an end user, these results benefit you too - while camera manufacturers claim that each new model gives you better image quality, if you already have a large collection of lenses, you can see what you gain, in terms of final image quality, by switching camera. It could be that changing to a higher resolution model actually shows up the flaws in your lens and so your net gain is minimal in changing camera models.
To illustrate this point about lens-camera efficiency, the graphs above show lenses tested on the Nikon D800 and D3X and the efficiency of those lenses mounted on those same cameras. What is very interesting, and indeed illustrative, is that while the P-Mpix scores for lenses mounted on the D800 are higher than when they are mounted on the D3X, the efficiency scores on the D800 are comparatively much lower.
The conclusions from this are simple - the Nikon D800 is definitely the leader in terms of P-Mpix score and DxOMark ranking, however the overall sharpness and performance of lenses on that sensor is not as good as it could be. It could be that the Anti-Aliasing filter is a little bit too strong adversely affecting the sharpness results. Perhaps with a slightly less restrictive AA filter, the efficiency results would have been improved.
So is switching from the 24megapixels of a D3X to the 36 megapixels of a D800 really worth it? Well, in overall terms, the average improvement in P-Mpix score of a lens on a D800 compared to a D3X, is around 10%. This is not a negligible improvement and should therefore not be ignored. However, bear in mind that this is an average performance increase, so some lenses such as the high-end prime models will show a greater improvement, while lower end zoom and super zoom models will not benefit anywhere near as much.
Beyond the sharpness scores, the other benefit of the Nikon D800 sensor is the improvement in low light, which must also be considered when looking at lens performance - while the P-Mpix score effectively measures sharpness, looking at the overall DxOMark score takes account of the improved sensor noise performance of the Nikon D800. If we look at the percentage improvement of DxOMark score in moving from the D3X to the D800, we see the gain jumping up to 15%.
Upgrading to D800 will indeed give you the sharpest result from all full frame gears published by DxOMark. Definitely worth it if you are already using the sharpest lenses available on Nikon mounts. However, don’t expect sharpness improvement proportional to pixel count.
Stay tuned for the next part of this review where we’ll look at the standard focal length lenses, zooms and primes as well as the macro lenses tested in the labs.