Canon vs Nikon. They never end. Lucky Sony, Olympus, Pentax and other underdogs for not having to deal with the stupid arguments. But this post isn’t about brand wars.
Expose to the right (ETTR) is a common advice in digital photography. It simply means, try to make sure that you expose your shot with bias towards the right end of the histogram. Make it as bright as practically possible without blowing out the highlights. If you understand how digital photos are stored, this makes sense. You want to maximize every bit of those 12-14 bits.
There is danger in blindly following this advice since the linear profile of digital camera sensors is not very forgiving. Once you clip past a certain limit, no data is stored in the photograph. This is characterized by blown highlights. Unfortunately, it is a lot easier to blow the highlights than lose the shadows.
There is something I discovered just a few months ago that I would like to share with you: It is better to underexpose than expose to the right. Not just underexpose but severely underexpose especially if the dynamic range of the scene is too wide.
Have a look at this photo because I quite pushed the camera beyond its limits when I took the shot:
Very dark isn’t it? The exposure was ISO 400, f8, 30 seconds after +2.5 stops of exposure compensation from the metered reading. That’s pushing the sensor a bit too much. I could have opened up to f5.6 but my cheap lens is very soft at that aperture. Going ISO 800, on the other hand, will only introduce more noise.
Now have a look at the same photo after post processing:
That’s a world of difference! I just pushed the exposure by +1.35 stops and then pulled some of the shadows with fill light. I have managed to extract details in the shadows while preserving the highlights. There’s more: peep all you want but there is barely a trace of luminance or chroma noise even after brightening the shadows. Amazing!!!
The photo was captured with a Pentax K5. It’s really amazing how modern sensors have improved. I would expect the same performance in the Nikon D7000 and Sony A55 because all of them use the same Sony sensor (surprise?!!!).
This is not the only instance where I managed to salvage a seemingly hopeless exposure. I do a lot of HDR work when the scene is too contrasty and I normally bracket at -2,0,+2. Many times, I was able to scrap the HDR because I was able to extract enough information from the -2 frame. Single exposure shots are still way cleaner than HDR so I always try to pull the shadows if I can.
Experiment with your own camera and see how much you can extract from a severely underexposed image. Make sure you shoot RAW.
So who’s coming with me to the dark side?
My new iPad blogging software ruined the original post. Lesson for me: sticking to one buggy software is sometimes better than switching software.