X-T5 at 12,800 ISO

JNR wrote:

Erik Baumgartner wrote:

baobob wrote:

and if reducing the noise is important expose to the right ETTR with +2/3 to 1 EV then in PP adjust highlights.

Actually, as Fuji sensors are quite ISO invariant in that range, so long as you are maximizing the sensor exposure, it doesn’t much matter where you set the ISO beyond 1600 or so. You can shoot at -3EV (ISO 1600 instead of 12800) and just push the brightness where it needs to go in post - no significant noise penalty, and you get significantly more highlight headroom to work with. ETTR is really only relevant at base ISO.

Agreed about everything here other than the last sentence. This week I got an opportunity to shoot at a club where the lighting has been pretty much the same as it had been for the past decade (very dark) and so got to do some good comparisons going back not only to the X-T2/20 shots, but earlier Pentax shots (on the 24mp sensor).

To the extent that I had "maximized sensor exposure" correctly, the ultimate processing in the 2000 to 6400 range from the X-T5 showed less noise and equal or slightly better sharpness. Of course, that involved a bit less sharpening and more NR than with the older sensor. A few times the sensor got tricked and lowered the ISO too far (yes, I use auto ISO in these variable light situations) - and the lack of maximized exposure resulted in slightly greater noise issues than with the old sensor. So, proper exposure is more critical with the 40mp sensor - as there seems to be more of a distinct shadow cliff.

I don't think I mentioned anything about image quality of the old vs. new sensors. From my experience playing with the 40MP RAW files, the IQ seems to be quite excellent when processed optimally (meaning not the same as the 24/26MP files).

It is likely that Erik and I have somewhat different understandings of ETTR... but to me it really does mean "maximizing the sensor exposure" and that should include low-light situations when you aren't filling the well.

I don't think there are multiple ways to understand it. ETTR - exposing to the right, means exactly that, exposing to the right.

It is always advantageous to maximize sensor exposure (SS/Aperture), but at anything beyond base ISO, while you still want to expose the sensor as much as possible, this isn't really ETTR anymore as you are now ISOing to the right (AKA "histogramming" to the right) which fundamentally changes the equation.

Exposing to the right is all about maximizing the signal to noise ratio and dynamic range. Recording the brightest highlights just below clipping at base ISO (ETTR) does exactly that. ISOing to the right, on the other hand, does not. While highlights to the right is generally a good idea, and it might may very well be appropriate to do this in most situations (and certainly is for jpeg shooters at DR100), by doing that in high ISO/high DR situations you are significantly limiting the dynamic range that can be captured. Exposing to the right always guarantees the maximum possible DR, but ISOing to the right does not, at higher ISOs, you can easily be sacrificing highlight headroom unnecessarily (and undesirably).