Ysarex wrote:
UniWB in conjunction with my SL's highlight clipping warning tells me exactly when two channels in the raw file have reached highlight clipping. Normal WB won't get me that..
I'm not interested waiting until the
second channel blows out. I want to know when the
first channel is going to blow out. If your highlights are close to neutral white (like clouds) that's going to be the
green channel which contributes 50% of the luminance information (56% for X-Trans).
As you are about to see, Daylight WB does this better than UniWB.
In the Daylight version, all three color channels reach their maximum at the same time as the green raw channel gets to its limit. What's more, the JPEG curves are not separated by much all the way from EC-2 to EC+3 and they come together at both ends of the range.
Just so you'll know, it was a pretty simple matter to get the Df to a UniWB setting that meets your expectations.
The new UniWB plots look very similar to
the earlier ones where you complained that they were not valid.
By the time the second JPEG channel (blue) blows out the green channel has already been blown out a stop earlier. That's why the UniWB blinkies show up too late. It's also why the Daylight version is set to start flashing about 0.3 to 0.7 stops before the raw file reaches the raw limit in the green channel, at least in the Df and other Nikons. They show up earlier on the A7 II and later on the Fuji X100T and the iPhone.
So any way you look at it, UniWB is not a good indicator for blown highlights.
But the most important thing to keep in mind is that, once you start to see blinkies, you are very close to blowing out the raw highlights and it may even be too late.
Besides, if you really care about this you should be at Base ISO where you stand the best chance of recovering any decent shadow information you might want.