Dual-Native ISO technology is a unique way of exploiting a camera’s sensor information to extend its dynamic range, and reduce the level of signal noise that is produced. The sensor will therefore be able to read two native ISOs on the sensor instead of one.

The technology was first developed by Panasonic with the VariCam 35 and later the LT, which had two levels of 800 and 5000,  and following that the EVA1 at 800 and 2500. Below we’ve put together a group-up explanation, and what this means for creativity.

The operation of a digital sensor

Bayer_pattern_on_sensor

Going back to the absolute basics, we need to analyse how a sensor works. Simply put, a sensor receives light on its photosites. The light will then be transformed into electric current according to the intensity of this light. This gives us an interpretation in shades of black and white. A blind photosite receives no light and therefore no current, whereas a photosite receives absolute white, and therefore gives a maximum current intensity. From this, to then get colour from black and white filters are inserted in front of the photosites and assigned to the three primary colours of red, green and blue.

Both luminance and colours can now be reconstructed thanks to what is called ‘debayering’, which is carried out by a learned algorithm in-camera or in post-production when recording in RAW. So now that we’ve understood the theory of how a sensor works, lets go back to our ISOs.

bayer filter in-cameraSensor performance of course depends on many factors, with sensor dynamics playing an important role in terms of the ability to keep all the colour information in highlights and lowlights.  For example, nothing is more complicated for a sensor than to film against day, with the background becoming burned and no detail in the shadows of the subject for example. A sensor with the highest dynamics will be able to retain maximum detail under these conditions.

The native ISO of a sensor constitutes the value of amplication that generates the least noise, and therefore the best signal to noise ratio. By analogy, imagine that you were recording a very weak sound with a dictaphone. To hear, you push the sound to the bottom and you get a very big breath when listening. With images, it’s almost the same: you have very little light and amplify the signal by increasing the ISO and therefore increase the noise level.

This is where the Dual-Native ISO sensitivity revolution comes in.

Instead of using only one amplification circuit optimised for “average” conditions, a second one has been added as shown in this diagram for the VariCam 35/LT.
Dual-ISO-explained

Each circuit has been dedicated to the best performance according to the conditions, therefore noise can be significantly reduced. This is the case for the EVA1, GH5S and VariCam series.

To go further, watch this excellent video produced by LensProToGo: