ETTR - Exposing to the right for noise reduction.

wow, many thanks to all who took time out to compile their lengthy and thoroughly educational replies. :clap: it's appreciated.

one thing that TP excels at over regular articles and tutorials is that you get a broader spectrum of real peoples experiences in more practical situations.

right, i'm off to play with the camera armed with some fresh info...... see you next week!! :thumbs:
 
Excellent thread, full of useful ETTR info - but I'll have to read it once more (at least !)
Mike
 
I've been having difficulty understanding this for a while now, I was just never able to get my head round it. Thanks to the responses in this thread though, something has just clicked. Really like the "Sunny 16" reference as well, going to try and put it into practice often so its easier to remember.
 
"Sunny 16" ???

Where does that come from :thinking:

DD

correction...sunny f16
the other levels are
cloudy bright f11
cloudy f8
dull f5.6
mrcrow bin it
 
Here is a white shirt shot raw with an exposure spot metered off the shirt at +4. Wherever it shows as red the pixels are being displayed at 100% saturation. If this was a JPEG file the red bits would be pure, featureless white and impossible to recover....

...

That's the power of raw and the ability to recover blown highlights. It is ideal for wedding photography (and everything else :) ). If that image had been shot to JPEG it would have been toast.

Small caveat on this. A white shirt (or swan in your other example) is a best case scenario for this approach.

Lightroom is very good at recovering luminance data from over- (and under-) exposed areas of an image, especially compared with, say, Canon DPP, which is more conservative in its approach. Where it is less good is recovering chroma data and I believe that it's simply not there in most RAW files.

With your test subject and the swan that may not matter too much as there's little colour in the subject. If the extreme point of the histogram is somewhere like a sky, however, you may find that there's some colour shift occurring in the 'recovered' area of the image. IME I tend to find that skies shift toward cyan on my 5D with Lightroom when pulling back from overexposure.
 
Sorry if this sounds stupid, but how do you go about getting back to the original exposure (albeit with a lot less noise) after exposing to the right? Do you just eyeball it? Or is that where your grey card comes in?
 
Musicman, I'm afraid that in my normal course of photography I do not need to recover my skies as I aim to expose the brightest important part of my subject/scene at +3 stops. I don't always get it right but I don't do a bad job. When dynamic range is so vast that I have to make sacrifices at one end or the other then I usually shoot to save the highlights.

I do recall a couple of years ago that Lightroom could do some weird things when recovering skies, but I thought it was a magenta tinge that could appear, not cyan. Mind you, despite owning six different EOS bodies, none of them is a 5D, so I don't know what the deal is with that camera. I do agree that DPP sucks for highlight recovery, but Lightroom really is very good and does not cause colour casts that I can see. It would be quite a feat of poor judgement to blow a blue sky, certainly by any more than 1/3 stop max. White cloud I can understand, but not the blue of the sky. Therefore I am puzzled that a cyan tint should spoil things. Are you sure the cyan isn't simply the blue of the sky starting to reappear?

Just as an example, when I was less skilled at these things, here is a photo from my 30D in which the sky is badly blown. First I present the unedited original, then a version with -1 on the exposure in Lightroom and then another at -2. I see no sign of colour cast in the recovered areas.....

20061006_123714-2_LR.jpg


20061006_123714-2_LR-2.jpg


20061006_123714-2_LR-3.jpg


The recovered grey clouds measure in Lightroom as perfect grey, where R=B=G.


Here's a very tricky challenge with available light, due to a massive dynamic range that the camera could not handle easily. The overcast sky had some bright bits and I wanted to retain the texture in the sky, so I had to shoot to save the sky, knowing I'd fix up the foreground later. Here is the image and histogram as shot, with just a white balance adjustment....

20091226_075254.JPG


There is just a tiny bit of clipping in the sky, but nothing of concern. The foreround looks like junk. But with my 12 bit raw files, and shooting at 100 ISO, it was pretty easy to pull up the details in the darker areas, with just three simple controls in Lightroom - fill, blacks and brightness. Here is the finished result....

20091226_075341.JPG



I guess the people needing to perform more heavy duty recovery are shooting into the light but metering off the subject, or perhaps leaving themselves to the mercy of autoexposure and paying the price for the camera not giving them what they need. Alternatively, perhaps they are confirming the success of their exposures by looking at the preview image on the camera's LCD screen. That is not the way to judge exposure. You need to review the histogram and look for blinkies. If you meter for the highlights then you should not have problems. I do not rely on having that extra stop of grace available. I plan my exposures to not need more than a snippet of recovery in the first place. The extra stop in reserve is just for emergency use if I make a bit of a cockup. Of course, regular checks for blinkies or dodgy histogram peaks soon put me back on the right track.

Remember, shooting raw and using ETTR technique is about capturing as much useful DATA as you can. It is not about capturing the perfect image immediately within the camera. By exposing for the highlights at +3 you guarantee yourself a good ETTR exposure that will record as much detail/data about the scene as it possibly can. You then take that data and craft it into the image you want using your raw editor. If you shoot with a Canon camera then I recommend using Neutral picture style on default settings in order to judge your +3 exposures. If your camera meter only goes to +2 then, using manual exposure, set an exposure from the highlights that gives you +2 on the meter and then simply add one more stop. You can do this with ISO, shutter speed or aperture, or a combination. If you shoot in an autoexposure mode and only have +/-2 stops of EC then you will run into a problem with my approach. Switch to manual and the problem is solved. :)

If you'd care to make available one of your blown 5D files with the cyan recovery problem I'd be interested to see how it processes in my copy of Lightroom 2.6. Personally I don't even bother to attempt recovery in DPP. Even with the relatively new highlight/shadow adjustments I find them to be crap. Lightroom is the daddy for good highlight recovery.
 
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