Ten stops of a 5DII

<p>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.</p>

 

<p>I shot a gray card in the sun.</p>

 

<p>Yes, as I wrote, boring.</p>

 

<p>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.</p>

 

<p>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.)</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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.</p>

 

<p>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?</p>

 

<p>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.</p>

 

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

 

<p>Cheers,</p>

 

<p>b&</p><div></div>

<p>In case anybody’s interested, here’s a graph of the numerical values.</p>

 

<p>Cheers,</p>

 

<p>b&</p><div></div>

<p>I got about half way through it and the boring part really hit home!</p>

<p>Very nice, Ben. For what it's worth, DPP shows the transfer function in its RAW tab, which looks very much like your charted values at its standard settings for Neutral/Faithful . The Standard/Portrait/Landscape curve is similar but with slightly more rounding in the shoulder. I have little doubt most cameras will show a similar response curve for a similarly carefully shot series. In any case, ACR and DPP have very similar, if not identical, response curves.</p>

 

<p>Good, Ben! I assume you filled the frame with the gray card and the ambient light didn't change (or not by any significant amount) during the exposures. The graph looks very smooth and nearly identical to that in DPP as Michael mentions.</p>

<p>Boring? Not at all...I'm going to do the same thing just as soon as I get over the excitement of cleaning the algae from the fish tank. ;-) (Seriously, thanks for posting!)</p>

<p>Thanks, Michael and Mark. Walter, don’t say I didn’t warn you!</p>

 

<p>I rarely venture into DPP any more, but I’ll have to have a look at this Transfer Function

doohickey of which you both speak.</p>

 

<p>Mark, I did fill the frame with the card — it took a couple tries because I did it all handheld,

probably would have been quicker to haul out the tripod anyway. But it was direct sunlight and clear

conditions, so the only source for variation would have been the angle between me, the card, and the

sun. And I don’t think I sway all <em>that</em> much for it to have a meaningful effect!</p>

 

<p>Cheers,</p>

 

<p>b&</p>

<p>Just one suggestion Ben. The "natural" ISO of the camera is 200, not 100 I believe.</p>

<p>I think you lost some highlights by exposing at ISO 100 instead of ISO 200, but you may have gained a little bit of shadow.</p>

<p>B G,</p>

 

<p>You may be thinking of Nikon instead of Canon. With Canon cameras, the lowest normally-

selectable ISO is 100, with 50 (usually) being available through expansion.</p>

 

<p>There have been some suggestions, based on image analysis, that the base ISO is really 160. But,

frankly, I wasn’t interested in anything quite so subtle.</p>

 

<p>Really, I wanted to get a better understanding of how the camera renders a scene, and

that’s what I got. I’m not interested in squeezing an extra fraction of a stop out of the

camera, but in controlling how real-world tones get mapped to the print. When I’m out in the

field, I’m really not going to be worrying about whether something is going to wind up in Zone

XIII.3 or XII.9.</p>

 

<p>Cheers,</p>

 

<p>b&</p>

With mine I just press the shutter release when I see something interesting. Ends up working out OK...

<p>I'm really glad that you did this so that I don't have to! What I didn't quite understand was why you had to do it?</p>

<p>John, Simply, to illustrate and understand how metering and exposure compensation relate to tone placement in the image, in his particular camera, for his particular initial development settings. He had to do it because the details that influence how he interprets the results are known to him. Conversely, secondhand reports found on the web are always suspect because of uncertainty of the conditions and the care taken or not taken in preparing the samples. It needs to be done, either personally or vicariously, as the first step in the guesswork game of setting exposure on the camera, whatever your fundamental beliefs. For an eggshell white texture, is +2 EV enough or too much? What, exactly, do the blinkies on the LCD preview mean when you shoot that egg at +2 EV?</p>

<p>Thanks Michael - I actually did understand his methodology and what he was trying to achieve. I would question whether or not it "needs to be done" though in the great scheme of creating images. </p>

<p>There are many facets to photography, enough to satisfy the interests and demands of everyone from scientists to artists to many different types of professionals to collectors. While it's not important to a scientist to be able to spot every iteration of a Leica from 50 yards, it's not important for a collector to know every nuance of bit depth, color space and the results of pixel peeping lens resolution charts. </p>

<p>Having been a professional photographer for over 25 years - shooting 8x10, 4x5, 6x7, 35mm and now both MF digital and DSLRs I know for sure that I actually don't need to do the above test to do my work. I shoot every day and process RAW files every day - I know exactly what highlight and shadow detail I can control and the contrast range of my images, experience - not scientific testing - has taught me that. However, photography for me is not about science, collecting or academic arguments - it's about images and everything else is secondary to that... composition, lighting, impact, emotion, mood, timing, etc. As long as my equipment and knowledge does not in any way hold me back, technically or creatively, I can concentrate on creating images for my clients and leave the minutia of testing sensors and shooting resolution charts and gray cards to the scientists.</p>

<p> </p>

<p>John,</p>

 

<p>You see, I <em>don’t</em> have 25 years of experience as a professional photographer. Not

even close. And I’ve only ever shot digital, not film.</p>

 

<p>Surely you’ve made test strips in your time? Did you never do a similar exercise as a

student?</p>

 

<p>As a child of the digital age, I’ve been brainwashed in the cult of ETTR. Exposure is

supposed to be all about histogram evaluation — worse, not about making sure that tones get

placed properly on the histogram, but about bunching the histogram as far up against the right side as

possible without blowing things out, and then fixing it on the computer.</p>

 

<p>Well, that doesn’t work — at least, not for me. I finally realized that I get the best results out of RAW files that need minimal fixing in post-processing, which

means I need to learn how to nail the exposure at the time I press the shutter. And, in order to do that, I

need to know how the meter relates to the result of developing the RAW file. That’s what this

exercise was all about.</p>

 

<p>Saturday afternoon, after finishing that exercise, I wandered around the yard and house with the

camera. I looked at an object, decided how I wanted to develop it, put the meter’s bug on it

accordingly, and shot a picture. First, I shocked myself at how close I was getting, right out of the gate.

Second, I surprised myself — I knew it already, but hadn’t really internalized the fact

— at discovering that, in a scene with the same lighting, if I was trying to match the exposure to

the scene, it didn’t matter what I metered; the final exposure wound up the same. That is, if I

metered something medium-light and set the bug a stop high, and then metered something

dark and shadowed and set the bug a few stops low…the on-camera exposure was exactly the

same.</p>

 

<p>Obvious, I know, but it’s not how we’re taught to meter a scene these days. I had to

learn it the hard way, and this exercise did a great deal in helping me do exactly that.</p>

 

<p>And, in mixed lighting, I had no trouble figuring out what would block and what would blow, and

therefore set an exposure that kept just what I wanted. One frame with the colorful sky richly rendered

and the shed and weeds in deep gloom, another with the shed and weeds merely moody and a pastel-colored sky, and a third with the shed and weeds in bright, diffuse light and a sky nearly devoid of

features. With (virtually) no guesswork. No way could I have done that before this exercise.</p>

 

<p>It also means there won’t ever again be any guesswork about HDR. I’ll know before I press the shutter if I’ll need it, and then I can make exposures for the different renderings of the different parts of the scene, already ready to be masked together after minimal development work. No more of this five-stop-spray-and-pray-bracketing bullshit and then trying to figure out what to do with it all.</p>

 

<p>If and when I ever upgrade bodies again, I’ll probably repeat this exercise. If there’s a

significant difference, I’ll remember how each camera behaves. If not, that’ll probably be

the last time I perform the exercise.</p>

 

<p>Cheers,</p>

 

<p>b&</p>

>>> However, photography for me is not about science, collecting or academic arguments - it's about images and

everything else is secondary to that... composition, lighting, impact, emotion, mood, timing, etc.

 

Yes, what photography is really about...

<p>Brad,</p>

 

<p>I agree completely. But it was John’s next sentence that got to the point of my

exercise:</p>

 

<blockquote><p>As long as my equipment and knowledge does not in any way hold me back,

technically or creatively [….]</p></blockquote>

 

<p>My knowledge had been holding me back, both technically and creatively. Doing the exercise gave

me knowledge I didn’t have before, knowledge that I can now easily apply to creative

decisions.</p>

 

<p>Cheers,</p>

 

<p>b&</p>

<p>Hey Ben, it sounds to me as if it was a useful and productive exercise for you - anything that helps with the learning curve can only be a good thing! </p>