Raw Histogram??

some go to 22%

Also Nikon Z 9 and Leica Q2M.

Hey Ted, having you and Jim in the same forum is neat!

What happens with those histograms when you start gradually lowering the exposure?

The raw histogram tells you how far your channels are from clipping in the raw data. If there is at least 1.33 stops of unused headroom, then you know that you could have exposed 1.33 stops more, and pulled the conversion down 1.33 stops.

There are more or less 3 points at which clipping can occur. The first is when the photosites are being read out; any photosite that has too much charge will be recorded as the highest number in the bit depth, by the ADC. Cameras rarely give you that real, initial raw data anymore, although many early digital cameras with raw did. Many cameras will multiply the original raw numbers and do additional clipping before writing the raw file. Then finally, the converter may cause clipping where there was none in the raw file.

And GFX. And Nikon Z. And Leica Q2M.

blog.kasson.com/a7riii/moving-away-from-sony-cameras/

"Meter readings of the gray card should be adjusted as follows:
- For subjects of normal reflectance, increase the indicated exposure by 1/2 stop."

"ln use, the Gray Card is placed in the same illumination as the main subject, and angled slightly toward the primary light source. An exposure reading is then taken off the 18% gray surface of the Gray Card ."

"The gray side of the card reflects precisely 18% of the incident light, while the white side reflects 90%. The KODAK Gray Card is manufactured to extremely tight tolerances. Allowable deviation in reflectance is 1%, an insignificant variation for any photographic process."

Kodak, "How to Use KODAK Gray Card"

It would give you information on how you could vary exposure (or ISO setting) to get maximum SNR without unwanted highlight clipping. The recommended exposure for an ISO setting in a camera is just that exposure for which the default conversion parameters would create an image with normal, expected "lightness". Most cameras can take more exposure than that without highlight clipping in raw mode, and then you can pull down the lightness in the converter, and the tones should look the same as if you didn't give the extra exposure and pull the lightness down, but with less noise and less potential artifacts in deep shadows.

So, with your camera set to ISO 100, you may be able to expose for ISO 40 with the ISO 100 setting, which will give you 1.33 stops less read noise, and 0.67 stops less photon noise.

The question of how much extra exposure you can give depends on the subject matter. If it is a black cat on a black couch that isn't glossy, then you might be able to expose the ISO 100 setting for ISO 16 or 10, with a single exposure.

Some converters do unwanted strange non-linear things when you play with their lightness-related sliders, though, so you need to make sure your converter can handle it. It would be theoretically possible to make an app that takes raw files and scales down the values and puts them in a DNG, so that the converter itself doesn't have to do the lightness pull-down, but I don't think anyone has done so. It is a shame when the first lightness-related slider in a converter isn't a simple linear scaling slider for the raw input, and any shoulders or knees or gamma applied separately.

At any ISO, every stop you can increase exposure decreases read noise by 1 stop, and decreases photon noise by 1/2 stop, relative to signal. You usually only have that luxury in situations where you can do that at base ISO (or the base of a higher dual-conversion-gain range of ISOs) If you have a very-high-DR scene, then you also keep your shadows away from black, which means less of a chance that you get that magenta or green tint that some conversions cast in deep shadows.

... for an average scene, but not necessarily for a scene that includes light or dark or strongly coloured subjects (Kodak used to stress that, advising bracketing -1, -1/2, 0. +1/2, +1).

It is interesting to note that there is no force "trying" to even these out, by looking at previous results. All of the absolute biases of the first 100 rolls remain no matter how many times further you roll the die; they just become a smaller proportion of the total. A "5" is no more likely for roll number 101 than a "4". If you randomly create lottery numbers to play, but forgot to play them and the numbers were picked, there is no rational reason not to play them for the next drawing, but there is also no rational reason to play them again, either.

When I go into NYC very early in the morning on the first bus, it stops at a Casino, and a lot of people that did an overnight in the Casino get on the bus. I hear some REALLY strange conversation after they get on.

Probably for another thread; I read your post and it doesn't say why, when you go to grab a camera for a particular use, you invariably choose one of the others over the Sonys. Longtime Nikon user is just curious...

Just guessing here -- it wasn't a rational decision.

I never cottoned to the Sony menu system.
I use a lot of Nikon F lenses (like the 105/1.4 and the 180-400/4), and there's no good Nikon F adapter for E-mount IMO.
The Z cameras feel better in my hands.

In a practical sense, that is going to depend a lot on your exposure strategy. If light is constant enough for you to keep up with manual exposure AND manual ISO, then you may only have to test the scene once to make sure you have no clipping, and until something brighter happens, your settings are good and you can be spontaneous. With blinkies, you would get a hard-to-miss warning as soon as it started getting brighter.

If you use an auto-exposure mode and/or auto ISO, however, you might want to back off a little more on ETTR than with full manual, as metering tends to run a little wild, even with current "intelligent metering", and even in consistent ambient lighting as different parts of the same overall scene are metered. You can see just how wild metering runs by looking at the passive meter in full-manual exposure/ISO mode as you point the lens at various parts of the environment, even when the lighting is even.

I suggest sticking to the traditional 18%.

Don Cox

It was nearly never 18% ;)

I would prefer "lightening" to "brightening".
If we use "brightness" for the scene and "lightness" for the viewed image (on-screen or print) things can be kept clearer.

Don