How Much Dynamic Range Do You Need?
If you thought last week's discussion was heated, this one will probably contribute to global warming. This week's image, by the way, was taken with a Nikon V1.
By my calculations, I needed a minimum of three more stops of dynamic range to fully open up the shadows on the left side, even more to get fine detail on the shady right side. Even then, given the low light and the small sensor, I'd be fighting with not enough electrons.
Or maybe not. I've deliberately left this rendering dark for a couple of reasons. First, I want to provoke a discussion of dynamic range;~). Second, it was dark. Not only is there no internal lighting during the day in most of this Quito church, but it was late in the day and the sky was full of menacing rain clouds. The feeling you got inside the church was pretty much what the designers probably intended: look up at the stained glass and the light from above. Thus, I've tried to express that in my post processing.
But let's say I had a camera that gave me unlimited dynamic range. What would happen then? I'd still have to post process, because our output media (prints, displays) has limited dynamic range capability. Anyone who talks about wanting more dynamic range also has to confess that they're a tonal rearranger. 14 stops of dynamic range rendered straight will look very flat in a print. Post processed correctly, it will look, well, dynamic.
So that brings me to this: the V1 is a small-sensor camera with little dynamic range, right? This image, though, proves it has more than enough for very tough subjects. Say what? Well, that wall on the right? It's post processed +3 stops and then carefully brought down in tonal value to where I want it. The stained glass you're looking at? Post processed -2 stops with 100% recovery. So whatever the base dynamic range of the V1 in a regular conversion, I've actually extended it 5 stops here via my post processing. And then, in order to recreate the visual impact of a church interior lit only by ambient light coming through stained glass, I actually took a lot of that dynamic range and either removed it in places, or moved it more than a stop in tonal position.
Is there noise? Surprisingly, not really. I didn't use any noise reduction at all in the conversion or post processing. There is a slight blockiness to the deep shadow detail that I've had to spend some extra time working on, but in a 24" print of this I doubt anyone would really expect it was an image taken with a small sensor camera.