On my way to see Anthony's first ski experience earlier in the month, I stopped by the Shirohige Shrine on the waters of Lake Biwa, in Takashima Japan, to take a few pictures. I posted a “washed out” picture of the shrine's main gate in the middle of the water that I'll repeat here:
I really like the washed-out effect in this shot, even though it's the exact opposite of what I generally try to get. I usually try to get the sunburst streaming in, like in these shots from my blog archive: Kouri Island (Okinawa) and Midwest America (Ohio) and Shogunzuka (Kyoto).
I'd like to say that the effect seen in this washed-out shot was one that I crafted using skill, experience, and natural talent, but it was due to none of those. Rather, it's the result of taking a high-speed burst of “bracketed” exposures, just to see what would happen.
I told the camera to capture as quickly as it could a wide breadth of exposures from way overexposed to way underexposed, and in less than 1.5 seconds, it took 8 shots: the most overexposed one allows more than 120× the light of the most underexposed one.
Along the same lines as the interactive Spot Metering Basics post from earlier in the month, here's an interactive way to visualize the over- and underexposing of an image: mouse over the green buttons to see different exposures of the same scene...
|-3 EV||-2 EV||-1 EV||base||+1 EV||+2 EV||+3 EV||+4 EV|
The center photo marked “base” has the exposure that the camera deemed proper at the time. Each one to the right (+1 EV, +2 EV, etc) is overexposed by double with each step, so the “+4 EV” photo allowed 16× the light as the base photo. Conversely, each one to the left (-1 EV, -2 EV, -3 EV) allowed half the light.
(“EV” means “exposure value”, and refers to how much light takes part in the making of the image. The term has an entry in Wikipedia)
Let's get more interactive...
One reason I shoot in raw format instead of jpeg is the latitude it affords in recovering from exposure disasters. It's somewhat academic, but I wondered how each of the non-base shots would look if I tried to correct each “wrong” exposure after the fact, in Lightroom.
If each raw image had perfect data, I could correct the underexposure or overexposure to arrive back at the base image, but since there is necessarily a limit on how much detail an image can hold, we would expect to lower quality in the results, and indeed that's the case. Click this button to enable another row of controls under the photo above....
Upon clicking the button, a yellow set of controls appears under the photo, which bring up copies of the photos that have been normalized to the base exposure. Again, if raw files had infinite detail, all the images in the yellow row would be identical to the green “base” image. (The yellow “base” image is the same as the green one; they're the same photo.)
For the severely-overexposed “+4 EV” green original, this attempt at correction during post-processing means attempting to reduce the exposure by four stops, but as the yellow “+4 EV” image shows, the result is pretty bad. (Toggle back and forth between the yellow “+4 EV” and the base photo to see what detail could not be recovered, even from the raw file.)
Still, when limited to +/- 2EV or even +/- 3EV, the results one can get from the raw files are not too bad... certainly, better than nothing, in a pinch. But what if I had shot in jpeg instead? How much could I have recovered from a wrong exposure then? Let's look...
Clicking on this button enables a third set of controls under the photo, blue ones which attempt to normalize jpeg versions toward the “base” exposure, just as the yellow buttons attempt to normalize raw versions. Again, the “base” photo is identical in all three rows.
Here, it's interesting to compare between the yellow and the blue rows. The lack of difference between the yellow “-3 EV” and the blue “-3 EV” tells me that the jpeg holds details in the shadows very well, and so when those shadows are boosted to compensate for the underexposure, the result is pretty good. It's very comparable to the raw version.
Highlights are another story, as there's notable degradation even in the blue “+1 EV” version, and it only gets worse further right.