Noise and ETTR

Started Feb 6, 2014 | Questions thread
Ido S
Ido S Senior Member • Posts: 4,932
Re: Noise and ETTR

Haven't clicked into the link that GeorgianBay1939 gave you, but I'll explain to you how I go by shooting with my OM-D E-M5.

First, You should understand what ISO truly is. By increasing the ISO, the sensor's voltage increases (something like that, I'm not great at electricity and all that stuff). This action is actually quite similar in its effect to bumping out the "Exposure" or Brightness in Lightroom. (I put Exposure in quotation marks, because by using that slider in Lightroom, the actual exposure is obviously not changed.) And so much like raising the ISO increases (or accentuates) noise, raising the Exposure or Brightness sliders accentuates noise. And I say accentuate, because it's not introducing noise - it's just making stuff brighter, and with it the noise that was there before making the adjustment.

So in Raw processing, the best thing you can do to fight noise, is to stay away from bringing up the Exposure or Brightness, or pushing the shadows too far (since you're using an old version of Lightroom, or an old processing version, it's called Fill Light). Whatever noise that's already there, is accentuated by this action.

In contrast, taking the Exposure or Brightness sliders down quite a lot, does not accentuate noise. Therefore, if you want the deep shadows of a photo to be lighter than what the automatic exposure gives you, then use the exposure compensation feature and over-expose the shot, while keeping an eye on the highlights and making sure they are not burned. I find that the E-M5's blinkies by default are too sensitive and for me sometimes hard to see, so either tweak the settings or do as I do, and shoot with a live histogram instead.

That way, the Raw file (and out-of-camera JPEG) may look too bright when you bring it into Lightroom, but you will also notice that the histogram's right side does not touch the edge (if you over-exposed correctly). Then you can darken down the image if needed, while keeping the shadows at hand and controlling them as you'd like. It may feel very refreshing at first - when I started doing that, I completely stopped bracketing exposures and combining them in an HDR software. Now I do 99% of my work on a single Raw file, when previously it was somewhere between 80% and 90%.

Make sure that when you're using the exposure compensation to over-expose (or rather, expose to the right), the shutter speed is changed, and not the ISO or the aperture. As I explained previously, bumping up the ISO will do you no good, as it would be exactly like taking the dark, zeroed-out exposure into Lightroom, and using the sliders to brighten the image. And the risk at changing the aperture to alter the exposure should be obvious - the depth of field will be changed!

If you haven't understood by now, then no, the ETTR method does not by itself reduce the amount of noise. But if done correctly, it will definitely correlate to that.

 Ido S's gear list:Ido S's gear list
Olympus 40-150mm F2.8 Pro Olympus OM-D E-M5 Olympus M.Zuiko Digital ED 9-18mm F4.0-5.6 Olympus M.Zuiko Digital ED 12-50mm 1:3.5-6.3 EZ Olympus M.Zuiko ED 75-300mm 1:4.8-6.7 II +1 more
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