Fuji X-series: Overexpose or underexpose high-contrast scenes?

Started 10 months ago | Discussions thread
Erik Baumgartner Senior Member • Posts: 3,857
Re: Fuji X-series: Overexpose or underexpose high-contrast scenes?

If you are a RAW shooter, “Exposing to the right” (ETTR) is indeed the way to go for maximum dynamic range and minimum shadow noise, but it is really only relevant at base ISO where it is good practice to record the important highlights as far to the right (of the histogram) as possible without clipping to ensure the maximum signal to noise ratio and cleanest shadow detail to work with later. I find the highlight warning blinkies to be the most reliable method for judging sensor saturation, far better than the histogram which can easily fail to register small areas of overexposure. With my usual jpeg settings (Provia, -1 Shadows, -1 Highlights, settings which do affect the EVF view and how the blinkies work), at base ISO and DR100, there are two things to consider for the RAW shooter - “just” blinking highlights are always fully recoverable in post (it’s generally OK to let specular highlights and direct light sources to “hard blink”), but if you have any blinking skin, back off the exposure compensation until it isn’t. This results in consistently fully exposed RAW files with maximum signal to noise ratio with no irretrievably blown highlights - easily accomplished with just your eyeball and exposure compensation assigned to the front command dial in “C” mode usually in Multi metering mode: Set your ISO to base value 160 or 200 depending on which camera you have, set the appropriate SS to eliminate potential motion blur (yours or uour subject’s, set the aperture for the desired DOF, compose you image normally, focus in the right spot, adjust the exposure compensation until the important highlights “just” blink (but not skin) and press the shutter button. A dull, flat scene will appear very bright in the EVF, and very high DR scene will often appear dark - it’s all about how the brightest highlights are recorded, not how “correct” the image in the EVF looks - a fundamental difference to optimal jpeg exposure.

It is important to note that neither the histogram or the blinkies accurately represent the RAW file (which is why some blinking is OK) Would it be better if we had metering and blinkies that accurately reflected the RAW file? Sure, but this actually works just fine. I know that some folks will make radical adjustments to their jpeg settings to get the histogram/blinkies to better represent the RAW file (Google UniWB), but I find this to be a monumental waste of time, the above method works just fine - it’s easy, quick, simple and your EFV looks normal while using it. If I’m ultimately being a bit conservative and leaving a tiny bit of highlight headroom on the table, I can live with that, the tonal response gets non-linear and unattractive right at the edge anyway.

In low light things are different.

Considering the invariant nature of the more recent Fuji sensors at ISO 800 and above (depending on the model), you don’t necessarily want to “expose to the right” for the best results. If you’ve maxed out your aperture and set the SS as low as possible to prevent motion blur, you’ve already exposed the sensor with the maximum amount of light possible - ISO is applied afterwards (either in-camera or in post in the form of brightness amplification and/or a tone curve) and it doesn’t make your sensor more sensitive or add any actual exposure, it is only adding additional image brightness to make up for the exposure shortfall. If you shot at ISO 800 or above you can boost the brightness (“exposure”) in post with very little to no noise penalty relative to initially using a higher ISO in camera (and risking blowing the highlights). So.... if you’ve already got your exposure maxed out using SS and aperture and your minimum ISO is set to 800 where the sensor becomes essentially ISO-less, you can simply adjust your exposure compensation (effectively the ISO in this case) so that the image looks “ok” in the EVF with no blinking and that’s it, you’re done. At ISO 800 minimum and no blinking, it matters very little where you set the ISO in-camera if the image looks reasonably decent (not ridiculously dark) in the EVF because you can adjust it later in post with very little noise penalty, but a big potential advantage in highlight protection headroom in different to meter situations. Setting the ISO higher in-camera to push the “exposure” all the way to the far right may limit the amount of highlight information you will have to work with later in post, particularly in high dynamic range/difficult to meter scenes.

I hope some of that makes sense. šŸ™‚

Increasing the ISO isn’t actually increasing exposure, it is brightness gain that is applied after the sensor has already been exposed, it can be applied in-camera when shooting or later on in post. If your sensor is ISO invariant, there is no significant downside to applying it in post, but there are some significant upsides. Once you’re above base ISO, and especially ISO 800 in the case of the newer dual-gain sensors in the Fujis, for the best image quality it makes the most sense to get as much actual “exposure” as you can manage by setting your aperture as wide as possible while still meeting your DOF needs, setting your SS to the lowest value that will prevent any kind of motion blur, and setting your ISO at ISO 800 or some higher value that is still well below where you might encounter any highlight clipping (the highlight warning blinkies are great for this). The newer Fuji sensors (Sony)are almost completely invariant at ISO 800 and above, so you’ll get pretty much the same image quality at ISO 800 with 3 stops of exposure push in post as you would at ISO 6400 in camera, except that with ISO 6400 in camera you have thrown away 3 stops of headroom and have possibly irretrievably lost some important highlight detail. If you “underISO” at ISO 800 you can push the brightness back up in post with no significant noise penalty compared to “correctly” exposing at ISO 6400, but you will now potentially have 3 stops of highlight information to work with in post that might have been lost otherwise.

 Erik Baumgartner's gear list:Erik Baumgartner's gear list
Sony RX100 Fujifilm X100V Fujifilm X-T2 Fujifilm X-T20 Fujifilm XF 35mm F1.4 R +4 more
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