HDRx with ISO instead of Shutter Speed

[Christoffer Glans]

So I was thinking, the reason motion looks awkward when shooting in HDRx mode is because the A-track and X-track use different shutter speeds, right? Therefor a sharp edge on one motion and motion blur on the normal exposure track.

Why don't we have a Dual ISO HDR instead? Using MX as example, it's native ISO is 800, but if the X-track is instead ISO100 while the normal exposure is ISO800, wouldn't that create a much better HDRx image than using different shutter speeds?

...and wouldn't this be possible do include in a future firmware? :smiley:

 

[Patrick Tresch]

Iso are metadata. You play within the DR of your sensor by adjusting iso. If you change it you won't change the noise floor and the clipping point. So ISO won't affect exposure. Only shutter speed (or a super fast iris change every X-frame ;-)) can change the exposed picture and create a HDRx frame.

Pat

 

[Elliott S Frank]

What Pat said.

Some other cameras, coming from a video heritage, use the ISO value to specify an amount of analog gain between the sensor pixel and the a/d converter that creates the digital values. In RED cameras the amount of light that lands on the sensor determines the digital value. The more light, the larger the value. Change the shutter angle (or the iris) and you change the amount of light that the sensor sees, as the frame rate is constant. "ISO" becomes a tool to set your zone, or to adjust your lighting.