Nikon D850 camera: dynamic range analysis

The Nikon company has announced the beginning of sales in America of a new digital SLR camera D850, which sets new standards for quality photo and video. It has a combination of high resolution, speed and light sensitivity. How realistic are the announced parameters of the new camera and what we get if we compare Nikon’s novelty with the capabilities of flagship models of other brands and even other formats? Today we will talk about the comparison with the medium format Fuji GFX 50S and the previous camera nikon D810, and in the next review with the SLR camera Canon 5D Mark IV.

Source –

dpreview.com

One of the most significant features in the D810 was the ISO 64 working sensitivity. Raw file recording is affected by two factors: frame resolution and continuous shooting performance. Higher resolution higher fraction of photons being registered will push the base ISO up, while increased full-capacity power capacity for electronic charge pushes it.

The D810 offered a lower ISO, increasing its overall capacity or at least finding a way to squeeze a little more out of it . This meant that it was able to capture as much light as it did on the D800, but could carry more light before it started to clamp. This meant that it could be given more exposure, which improves the signal to noise ratio and gives cleaner image tones: improvement is often interpreted as improved tonality.

This ability to withstand the extra 2/3EV exposure is because we’re saying that the D810 can compete with the latest batch of medium format cameras whose 44 x 33mm sensors will capture 2/3EV more light at the same F-number and shutter speed.

This is how the D850 manages to repeat the trick? Yes, of course it does.

Similar noise performance in deep shadows implies the same dynamic range, unless it previously cut off highlights. Bill Cluff’s data indicates that this is not the case, and that the overall ISO DR base is just as good.

We also confirmed that the dynamic range results remain identical in continuous drive modes, unlike many Sony ILCs, which go down to 12 bits.

Benefits of BSI, high ISO performance, and ISO invariance

We were always told that BSI sensors wouldn’t offer much efficiency in larger sensors because the pixel circuitry, which might otherwise get in the way, was only a small fraction of the light-sensitive area in larger pixels. Instead, Nikon says the main advantage of the D850 was that it allowed them to incorporate the extra circuitry needed to provide higher readout speeds without having to worry about it falling on some of the light gathering in the pixel.

Theoretically we could also see some performance advantages in the corners with wide-angle lenses, but that doesn’t come into play with the 85mm lens we use for these tests.

However, while we don’t expect the move to BSI to produce a significant improvement in high ISO noise as a result of improved efficiency, we do expect some of that to come from the D550’s dual gain design. This uses a different readout circuit with a higher gain for higher ISOs, which slightly reduces readout noise, but reduces the amount of total capacity you can use. Because, at high ISO, even a small amount of reading noise is multiplied many, many times, any reduction is valuable. At these settings, most of the sensor capture is amplified to the cutoff, so reducing the full capacity is a compromise. So we can see that the camera’s baseline ISO performance is unchanged, but from ISO 400 upwards we should see an improvement in noise performance.

This approach means that the D850 is not ISO-invariant, but it’s not: not because low ISO modes add a lot of reading noise, but because higher ISO modes can add even less.

Of course, like the D810, if you lighten the D850’s ISO 64 shots, they will have more noise than if you shoot at the same exposure using a higher ISO. Add a little more gain at the lower end, starting at ISO 100, and the results are very similar to what you get by initially shooting at ISO 6400 which are noisier than the ISO 64-4000 series, as the latter were given more exposure .

Once you get above ISO 400, where the sensor switches to a higher gain pixel level, there is no fundamental difference between shooting at ISO 500 and brightness , and shooting at ISO 4000.

This makes it rather unfortunate that Nikon – and most camera manufacturers – choose the brighter ISO shots in the camera rather than the Raw converter. The latter would offer a few stops of potential D850 event information – and most cameras – just throw away.

At ISO 4000 and 6400 you can start to see the higher gain of the D850, showing a slight improvement in noise compared to the D810: a difference we expect to see as you increase the ISO settings.