12K Sensor - Dynamic Range Shift at 8K/4K Readout

Could someone here (perhaps an Ursa Cine 12K owner) expand on the dynamic range shift that happens when changing to the 8K/4K recording modes? The website shows an additional stop in the shadows with one less in the highlights. Does this effectively make the camera more sensitive, as in 1600 base iso vs 800 rated?

I tend to rate Blackmagic sensor always a stop under but have no experience with this 12K sensor, so any experience would be appreciated. Thanks!

From what I'm seeing it seems like it's a ⅓ stop loss. 1/6 in the highlights and 1/6 in the shadows. I don't have concrete data to back up this claim, but this is what it feels like when I'm switching from 12K to 8K. I believe that in the Filmmakers Academy livestream over a week ago that Shane Hurlbut asked Tor what it was and got a confirmation on the amount of dynamic range difference. But I cannot perfectly remember. Maybe someone from Blackmagic can give a definitive answer.

Hi Tim - appreciate the quick reply. The charts on the Blackmagic website don't show an overall loss (which at a 1/3 stop would be totally fine for me), but rather a shifting by one stop downards (so +1 in the shadows, -1 in the highlights).

[CaptainHook]

Does this effectively make the camera more sensitive, as in 1600 base iso vs 800 rated?

The sensitivity is "compensated" for, so ISO800 is still ISO800 with similar noise performance. You just have the ~1 stop shift in DR distribution.

That increase in dynamic range below the line makes the 8K more cinematic considering this craze on the last few years to produce images where significant action and expression occurs in the shadows (making some shows almost unwatchable on a poor man’s classic HDTV sadly), but more immersive and evocative on modern 4KTV OLED sets.

CaptainHook thanks for clarifying! So if I wanted to keep the DR headroom the same at 8K compared to 12K would you recommend using ISO1600 and decreasing exposure by one stop? Or would that introduce unnecessary noise? Basically trying to understand how to expose this camera if I mix 12K and 8K modes in the same contrasty daylight exterior scene that requires the same highlight latitude, for example for shooting detailed landscapes in 12K and then close ups of faces or fast moving action shots in 8K (for the rolling shutter or to preserve data)

[CaptainHook]

Test as much as you can and see what works best for you. You may indeed find you prefer ISO1600 at 8K, but you might also find your preference changes in different environment/conditions, based on desired aesthetic/delivery requirements/etc.

When trying various ISO might also want to check different compressions.

… You may indeed find you prefer ISO1600 at 8K, but you might also find your preference changes in different environment/conditions, based on desired aesthetic/delivery requirements/etc.

Very interesting and good news for me when I move to Pyxis. For about a year now, I’ve been getting good results on theatrical performances and music concerts where I shoot with ISO 1600 and T5.6 lenses on both the BMPCC4K recording Q1 and UM4.6K lossless CDNG. Comforting to know this practice can continue with the Pyxis.