Ilkka Nissila

Dual pixel AF with 45MP final output image would require a natively 91MP sensor and for continuous AF purposes all of this data would have to be read and processed during focusing. Cross-type phase detection with a quadruple pixel design would require 182MP (if 2x2 are used instead of some other pattern). These things are easier to implement in a camera that isn't intended to produce high-resolution stills. Dual pixel AF is limited by the processing power available and having a high pixel count makes it more difficult. Notice that Canon's 50MP models don't have dual pixel AF either. D2H and D2Hs had an LBCAST sensor. I think the main problem wasn't the technology of the sensor but the fact that it was 4MP while Canon's was 8MP. The D2X had a 12 MP sensor but Nikon hadn't yet cracked optimal high ISO at that time (the breakthroughs came later with the D3s). In my opinion, the details of how Nikon collaborate with their partners to make the sensors for their cameras should not matter to the customer. Users should be interested in 1) image quality, 2) performance, and 3) cost. If the results are excellent that is usually enough. It is clear that Nikon's focus isn't in video but they offer video as a feature (instead of the primary function of the camera). Nikon seems to prioritise still image quality over features such as video AF. This is neither a good thing or a bad thing, every company would do well to concentrate on their strengths. I do think Canon may be more motivated to offer full frame 4K in the near future because both of their main rivals now offer it. Since Nikon are planning on releasing a high end mirrorless camera system in the future, that will surely require some kind of on-sensor PDAF which then can be offered on the DSLR side as well.

Noise depends on the luminosity or number of photons detected; it is not constant but increases approximately proportionally to the square root of the signal (the luminosity or photon count). The number of distinct tonal or colour values (that can be distinguished from noise) can be calculated if the SNR is known as a function of luminosity or RGB values. From this graphs it is possible to calculate how much tonal or colour information there is in the image which is what DXOMark is estimating. You cannot estimate how many colours or tones are separable from noise by assuming that there is a fixed "noise floor". In my opinion the DXOMark analysis here is sound. Color depth is just the number of bits that are used to encode the colour values of the pixel. It doesn't consider noise.

If you look more closely at DXOMark measurements (the graphs) the D5 has better dynamic range from about 3200 to 51200 than the 1DX II. Which is more important (low ISO or high ISO dynamic range), can be argued depending on the application. Typical sports shooters are shooting publication ready jpgs in the camera which mean their dynamic range is limited at that point in practice even if they once in a blue moon get the chance to use low ISO. Furthermore the tonal range (number of tones that can be separated from each other and noise) and color sensitivity (number of color values that can be distinguished from each other and noise) are greater in the D5 across the 100-25600 range than in the 1DX Mark II. For me these are very important measures of the smoothness of tones and colour gradations especially if the contrast is increased in post they determine how well the image's tonal and colour integrity hold up. To decide on which sensor is best for a given application, one needs to look at the shooting conditions and what kind of post-processing / look is preferred for the final image. The D5 isn't the ideal camera to shoot in direct sunlight due to its lower base ISO dynamic range; that much is clear. On the other hand, the 35mm full frame camera which has the best base ISO dynamic range is also made by Nikon: the D810. So they have solutions for this situation also, just in a different camera. The D500/D7500 sensor allows fast reads for high fps use, which the D7200's sensor (which scores better on dxomark for low ISO metrics) is apparently not well equipped to do. However, many users of the D500 report that they find the high ISO image quality to be better in the D500 than in the D7200 and the color neutrality is held across a greater range of ISO settings than in previous cameras. This is also true of the D5. So there are characteristics of the new sensors which are missed by dxo's overall scoring (which is mostly based on low ISO performance and ignores large parts of the elevated ISO measurements) but appreciated by photographers who use these cameras. In dxomark's graphs, the D7500 has better dynamic range than the NX500 at every ISO setting but the difference is pronounced from ISO 400 to 25600. DXO weight their overall score heavily on base ISO results which is usually not what people are using in practice unless they work in the studio or are tripod based landscape photographers. I think there is useful information in DXOMark data but you have to go into the graphs in the Measurements tab to access it. I think the cropped 4K (which is the same actual pixels crop as is used in Canon's 4K capable DSLRs) is used because it requires less processing and produces less heat than doing a full sensor read and resampling the images to 4K. I don't think it's a question of who makes the sensor so much. If they wanted to they could make a full frame 4K camera but it would cost more and most Nikon users are focused on still photography and only need some video capability on the side for occasional use. I realize you are interested primarily in video and would like Nikon to do better in that area. I am sure this sentiment is shared by many, however, Nikon's history is in still photography and they remain primarily focused on that. Users who have greater priority needs in video tend to congregate to other brands. Since Nikon is working on a full frame mirrorless camera I would expect that they will implement some form of phase-detect focus sensors in the main image sensors and at that point there will probably be more interest in using Nikons for video. But at present it seems that all the optimization that Nikon do is to get the best still image quality possible for the applications expected for each particular camera.