EI - RAW

[PSil001]

Hello,

I understand that the sensor has a native ISO of 800 and any adjustments on the EI will affect the distribution of the 14 stops of dynamic range.

So when shootig raw, if for example I set the EI to 200 instead of 800, does it mean that the sensor will now be registering less light or it´s the same amount but the monitor shows a darker image (as if the EI was just a ¨lut¨ for monitoring)?

Also, is it the same logic when shooting prores?

[Jan Heugel]

Hi there,

the ISO setting defines how the light registered by the sensor's photosites is being interpredted by the camera's image pipeline. In case of ARRIRAW this information is "only" metadata an can be changed in postproduction. Regardless of the setting there can't be more light or less light. So when you record ARRIRAW with ISO 200 you can cange that to ISO 800 in post. It will look like if you had chosen ISO 800 in the first place.

Since ProRes 422HQ up to ProRes 4444 XQ is not a raw codec ,the image signal travels through the whole image pipeline and the ISO setting is applied to the image and cannot be changed afterwards.

But changing the ISO influences the portrayal of light above and below neutral grey.
See attached image.

Cheers,
Jan

[PSil001]

Thanks! As you mentioned this chart, I understand that for the Alexa Mini when you set the ISO, this affects the distribution of its stops of dynamic range above and less midgray. So its common to hear dps saying its best to choose low iso for dark scenes and higher iso for bright scenes.

With the Alexa 35, this logic is still applied?

For example, in both situations below the image exposure will ended up the same but the first one would distribute the dynamic range more between the shadows and the second more for the highlights?

180 degrees, f2 , ISO 200
180 degrees, f5.6 , ISO 1600

[Jan Heugel]

Yes it applies to ALEXA 35 alike.