Ten stops of a 5DII

So, today, I did a boring exercise I haven’t done in ages. I’ve been meaning to do it with the 5DII for quite some time, but have’t gotten a round tuit until today.

I shot a gray card in the sun.

Yes, as I wrote, boring.

Attached is a synthesized summary of the results. The big numbers indicate how many stops over or under the center of the exposure scale the bug was at the time of the shot. The little numbers represent the L* value of the patch in the Lab color space.

I processed all pictures in Adobe Camera Raw with the most neutral settings it has, which I personally use as the starting point for all my work. That would be the development sliders set to their default position, except for blacks at 0; the linear tone curve selected; and the Camera Faithful profile. And, of course, I set the white balance off the card. (Actually, quite unsurprisingly, the auto white balance was perfect; I just made sure all frames had the exact same setting.)

Once opened in Photoshop, I used the Average filter to figure out what colors each exposure wound up being. There were a few shots with one of the RGB values different from the other two by one unit; I didn’t attempt to duplicate such insignificant hue shifts but rather made all the synthetic patches perfectly neutral. The shifts were more likely due to my lazy technique (I did the whole thing handheld, for example) than anything else.

There are a few things worth discussing, I think. First, and most obvious, is that there are a lot more shadow patches than highlight patches.

As the ETTR proponents will be quick to point out, yes, there is a lot of recoverable headroom. In this particular lighting situation of this particular (and decidedly uncommon) scene, I probably had about three stops more before it would become unrecoverable. That’s good to be aware of, but I personally think that the safety margin this represents is perfect. If I have something I want to render as bright yet retain detail and be colorful, I know that I can put the bug at or slightly beyond the top of the in-camera meter and it should be just fine. Things a few stops below that will render as mid tones, which is almost guaranteed to be what I want, anyway; if not, it’s probably HDR time.

And, indeed, that brightest patch wasn’t entirely blown, even in the ACR preview; it was about ¾ blown. A third of a stop of the exposure slider would bring it entirely out of overexposure.

Moving down the scale, the middle stop is a half a stop hot. I’m okay with that. When I’m creating art, I tend to like bright midtones. It’s also about as much baked-in ETTR as I would ever be interested in. When I’m copying art, I’m shooting tethered and I adjust the lighting until the rendered file is as close to correct as possible, so the in-camera meter doesn’t matter.

Moving down the line, the shadows are all as clean and noise-free as one could ever hope for. (Of course, I did all this at ISO 100.) The darkest could be boosted by one stop without having to do anything heroic as far as noise reduction goes, though two stops would indeed require heroism.

What I find most remarkable is that you have to go all the way down to six (or more) stops below the middle before you get to Zone 0. In practice, one would probably use the black slider to crush the shadows, but even the default settings in ACR don’t apply a full stop of black point clipping. So, as long as you don’t intend to under-expose and compensate in post-production, there’s no reason to fear putting your shadows exactly where you want them to be on the print. Make sure the darkest thing you want to retain detail is at or near the bottom of the in-camera meter, and you’re set. But if you want an all-black background (for example), be sure that your midtones are at least a half dozen stops above the background. If it’s a low-key shot against a black background, you probably want at least four stops of separation.

Combine that six-stops-under with the three-stops-over plus the recoverable two-or-three-stops-seemingly-but-probably-not-really-blown, and you get about a dozen stops of dynamic range in a single exposure. Remarkable. Of course, the extremes will likely suffer, and you’ll have a hell of a lot of work squeezing it all into something you can print, but still.

That last thought really brings me to my original point in this exercise, and why I chose the ten stops for this final rendering that I did. For me, this represents the usable tonal range of the camera-RAW converter-monitor-printer toolset. The five in-camera stops do, indeed, seem to be perfectly suited for creative expression. Put your highlights at or around the top and they won’t clip; put them a stop above only if you don’t object to clipping, and two if you really don’t care about clipping. Put your mid-tones at or around the middle and they’ll take care of themselves. Put your detailed shadows at or around the bottom and you’ll get lots of clean detail; put them a stop or two below if you just want them to be texture or if you don’t object to a bit of recoverable noise. Plan on dramatically shoving the bug to the left to get pure black, but only a stop to the right for the default RAW settings to get pure white. Which, I hope, is exactly what this chart says to the rest of y’all.

Granted, I might not be squeezing the absolute theoretical maximum possible out of the sensor with this approach. But, really — who needs more than what this represents in a single exposure that’s eventually headed to a piece of paper by way of a monitor with a gamut only slightly larger than sRGB? The camera is no longer the weakest link in the chain. And, what I get in return is a greatly simplified, more intuitive, less error-prone workflow that produces better prints. What’s not to love?

I would encourage y’all to try this experiment for yourselves, if you haven’t already, with your own favorite post-processing recipe as your starting point. If you always start with the strong contrast tone curve and the Landscape picture style with blacks set to 8, or if you use a different RAW developer entirely, you may well come up with some significantly different numbers — and it’s those numbers you should care about, not mine. If you shoot at a different ISO setting, your numbers will probably change. And they’ll almost certainly change with a different camera.

I would be curious to see those numbers and an explanation of how you got them, though….

Cheers,

b&