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A search for "native ISO" shows a lot of explanations, which can be generally understood as sensitivity with no digital gain and the best dynamic range and noise performance. For a long time, most sensors had only one native ISO, the lowest value of standard sensitivity-for most cameras and mobile phones, the native ISO was ISO 100.

* many cameras can reach ISO 50 when the extended sensitivity is turned on, but this is achieved through in-machine processing and does not increase the dynamic range. Of course, there are many cameras whose "native ISO" is not ISO 100s. For example, the Nikon D810 series / D850 / Z 7 series / Z 9 can reach ISO 64, while some M4amp 3 cameras are ISO 200s.

* * when shooting a video, the native ISO may change due to different gamma curves. Usually when recording in LOG mode, the native ISO will increase by 2-3 gears (for example, from ISO 100s to ISO 800s).

However, the new generation of sensors generally have one high and one low native ISO. In low sensitivity, lower native ISO is used to obtain larger dynamic range; in high sensitivity, higher native ISO is used to reduce noise. For this technology, Sony, Panasonic, Sima and other manufacturers call it "dual native ISO", Samsung calls it "smart ISO", and Canon uses multi-block "basic sensitivity" or "reference sensitivity" to describe it.

There is more than one way to achieve "dual native ISO": some use two sets of gain circuits, and some switch the trap capacity of pixels. To be sure, "dual native ISO" is the hardware feature of the sensor.

TIPS: how can I tell that my camera supports "dual native ISO"? One is to inquire about the commodity details page of the official website, and the other is to refer to the dynamic range dots and lines of websites such as photonstophotos. The following figure is an example: the green dots and lines (Sony 7SM3) shows an inflection point here in the ISO 1600, and the dynamic range is better than the ISO 800s. The other two lines (Sony 7s and 7SM2) do not have such an inflection point, that is, there is only one "native ISO".

Sony's new generation of backlit and stacked CMOS (including cameras and mobile phones), and Samsung's new generation of mobile phone sensors basically have dual native ISO.

* you only need to pay attention to the solid circle. The "dual native ISO" of most cameras and mobile phones can only work in "switch" mode, while a few products can make two native ISO work at the same time when shooting video, achieving a larger dynamic range through fusion. This practice is called "dual-gain imaging" on Canon C-series digital cinema machines (except DGO,EOS R5C), Panasonic GH6 calls it "dynamic range enhancement", and Xiaomi 10 Ultra / 11 Ultra is called "dual native ISO Fusion".

▲ Canon DGO Image Sensor

Dynamic range lifting Mode of ▲ Panasonic GH6

What is the difference between the "double native ISO Fusion" knot of ▲ Xiaomi 10 Ultra and the double gain? In the final analysis, ISO is gain, so "dual native ISO" can also be said to be double gain (today, many cameras can choose to display ISO or gain db).

What we really need to know is:

-now, most cameras and mobile phones have two native ISO, which can improve the noise in high light sensitivity by switching to the second block native ISO-switching work and improving noise, which is suitable for both photos and videos.

-A few cameras and cameras can not only make the two native ISO switch, but also make them work and merge at the same time when shooting video, so as to expand the dynamic range-- work at the same time to improve the dynamic range for video.

This article comes from the official account of Wechat: camera Notes (ID:xjbiji), by Teng Fei et

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