ASA rating on Blackmagic Pocket CC

Hi, experts! I followed the great advice of others on this forum and got a Blackmagic Pocket Cinema Camera and have been playing around with some different lenses in different lighting situations.

When it comes to the BMPCC ASA rating, is it best to keep 200 for daylight and then move to higher numbers for darker shooting?
 
Nope. Here's why:

A user on another forum said:
Some image sensors have Analogue gain applied in order to push the image sensor to different ISO settings without causing too big a shift in noise or dynamic range. Others do not have this analogue gain and so the sensor is always operating at its native ISO.
The BMCC and BMPCC have the latter. The Sensor is always at iso 800. This setting allows for the greatest dynamic range. If you set the camera to any other iso setting, it is just being push or pulled digitally.

At ISO 400 for example, you have a smoother image, but slightly lower dynamic range - this is because the image is being recorded at 800 and then pulled to 400, which pushes the noise floor lower.

At ISO 1600, the camera does apply a bias towards the shadows during the sensor readout from analogue to digital - but the sensor is still operating at 800.

If you did shoot at iso 200 on a bright sunny day for example, what you would be doing is capturing in camera at iso 800 - then pulling the exposure down digitally, which would lower the dynamic range of the shot, but also clean it up too. Because the sensor is always running at 800, the clipping in the highlights stays the same at 200 as it is at 800 - so turning down the ISO is not an efficient way to reduce the brightness of the scene -as it loses dynamic range. Much better to use an ND filter.

Some users have concluded that they prefer to shoot at ISO 400, because the image is cleaner and the DR loss is minimal.

When filming in Raw, the pulling or pushing is flagged to be done during the processing of the footage, its just meta data applied to ISO 800 footage. When filming in ProRes or DNxHD, the pushing or pulling is baked into the video file.
 
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