Matt Thela wrote:Savannah Miller wrote:The Blackmagic camera does not use gain like other cameras, so instead you can think of 800 as the cameras Exposure Index. The camera really does not have any other ISO settings, and really those ohter ones are almost the same thing as if you push the color correction in post. You can get the same thing with non-raw clips if you go in and use a Color Space transform node to convert the image to xyz linear and use a serial node with gain adjustments before converting back.
You don't necessarily get "more" dynamic range at a certain ISO, but visually, changing the ISO sometimes gives you the opposite effect of what you want, hence why dynamic range appears to be less. It would be more ideal if you got shadow dynamic range when you RAISE the ISO and HIGHLIGHT dynamic range when you lower the ISO since that's what you need when shooting in those conditions, but the opposite happens. So whether or not, you want to change the distribution of DR decides whether you should change the ISO.
If you're using the Blackmagic Rec 709 lut, that's designed for broadcast and does not give you the full dynamic range of the sensor. Some of your highlights look blown, and if you're grading using the standard LUT, you'll probably get worse results than using other cameras and their default color profiles.
I don't still think that for the wedding market, there's any huge advantages the Ursa Mini Pro has over competitor cameras that offer more convenience.
Thanks Savannah, When shooting Raw I use the "Film Log" option when shooting, not the Video option, not sure if thats what your referring to.
I typically don't use Luts while grading in Resolve (Besides the Film log thats applied in Raw settings) But tweak the Raw options till I get the basic grade then add other things like some slight orange/teal and skin tone stuff on other nodes depending on the clip
That's interesting about how raising the ISO doesn't help shadow dynamic range and visa verse, didn't realize the opposite happened, but that's the good thing with raw I can change the ISO Setting. Good tip, thanks for mentioning!
In RAW you can change ISO, but it's really only useful if you expose for a certain ISO. The easiest way to describe it, is the camera is ALWAYS at 800 ISO no matter what. The other ISO settings are fake. Just like when a camera has some sort of extended ISO range in the firmware, this is exactly the same thing. It's not real ISO. Instead, it's basically a color correction that is applied to linear sensor data to gain the recorded sensor values. That's why converting Prores film into xyz linear gives you approximately the same result. Because when you gain linear sensor values, you can properly change exposure in the mathematically correct way without bias from the film gamut.
So by exposing for 1600 ISO, it's basically the same thing as a 1 stop underexposed image that's lifted one stop in post, hence why you get 1 extra stop of range in the highlights. An underexposed image gives you more highlight protection. Likewise, a 400 ISO image is the same as overexposing to the right by 1 stop and then grading it back down, hence why you get more shadow detail.
What I was saying, is something about your highlight dynamic range is suspect. It's clipping way to heavily which is suggesting you were doing something in resolve to cause the clipping. If you interpret the RAW files as REC 709 in resolve, then that could be the issue. That color transformation has a very limited dynamic range and is only intended to match the Rec 709 standards for broadcast. Also the BMD 4.6K film curve has extra dynamic range stored in the superwhite areas because otherwise, the film curve would be much flatter due to the high amount of dynamic range the camera has. Certain nodes and corrections will clip this data if you're not careful.