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Book Bag: Understanding Exposure
14 March 2016
The fourth edition of Bryan Peterson's Understanding Exposure will be released tomorrow. We paged through an advanced copy for this review of the 176-page book which features all new images for this edition plus a new chapter on using flash.
We had a lot of fun, frankly.
We had fun because Peterson has a habit of leaving crucial bits of information out. It was a thrill to read through a section and stop every few lines to wonder why he didn't mention this or that, which (you know) might have affected his argument.
You may not enjoy that as much as we did, though. So lets give you a few examples of what we're talking about.
Take the title, for one. He left out the word "Manual." Properly titled, the book should be called Understanding Manual Exposure.
Peterson is an advocate of manual exposure. And we applaud that approach, certainly. As he points out, it isn't that tough. And automated exposures are wrong just enough to make the manual approach rewarding.
But he doesn't mention that he's referring primarily to outdoor shooting. You know, where the sun or cloud cover maintains a pretty constant illumination. Manual exposure can be untenable in a venue where the light changes constantly. In that case, you control what really matters to you and let the camera take care of the other factors.
You only have to wait until page 10 to get Peterson's magic formula, listing those factors:
A correct exposure is a simple combination of three important factors: aperture, shutter speed and ISO. Since the beginning of photography, these three factors have been at the heart of every exposure, whether that exposure was correct or not, and they still are today -- even with digital cameras. I refer to them as the photographic triangle.
You probably knew about aperture, shutter speed and ISO already. It's pretty old news.
Peterson has a soft spot for old news, though. He's not particularly impressed with modern camera technology, which he suggests resembles "the cockpit of a Boing 747-400."
So don't be surprised that he isn't charmed by high ISOs. And high for him is anything over 400. On page 15 he shows us a night shot of Prague taken at ISO 400 instead of "super-high" ISO 1600.
But here again, he's omitting some important information. He doesn't want to lose the highlights in the image, so a high ISO (even though it's a night shot) is not appropriate. He wants something that will hold the detail of the buildings illuminated by street light. And the darkness beyond should be dark, not middle gray.
It's a whole different story when the baby comes home and grandma holds the peanut in an easy chair across the room from the only table lamp. Then you'll want ISO 1600. And Auto 1600 would be even better so the camera can swing back to ISO 400 when Mom takes the baby back under the table lamp. You can follow the action instead of worrying about your camera settings.
His discussion of light meters is critical to understanding what your camera is telling you about the light but again he leaves out an important reason to use an external meter. He does mention their existence but he doesn't tell you (as we have) that only an external meter can take an incident light reading.
He does mention that cameras are capable of "upwards of 9 stops of light to dark exposure, and at this rate a sensor soon will be recording the human eye's ability to see a 16-stop range." But here's how Ansel Adams explained the same issue:
We must also consider the nature of a photograph. A black-and-white print has a maximum range of brightnesses (reflection densities) of about 1:100, or occasionally more. That is, the deep blacks of a print made on glossy paper reflect about 1/100 as much light as the lightest areas. No matter how great the scale of brightness in the original subject (which can be as high as 1:10,000) we have only this range of 1:100 in the print to simulate it.
Adams begins with the print and Peterson never mentions it. Cameras don't see, they capture. The data they capture is reproduced in a print or on a monitor, both of which limit the range of brightness that can be represented.
What does that imply about a "correct exposure"?
When Peterson says "correct exposure" he means a balanced one in which highlights are not blown and shadow detail is no more muddy than it has to be. But is he talking about exposing for the limited range of a JPEG capture or exposing for the larger range of a Raw capture? And what's the difference?
He doesn't say.
We get a hint when he talks about his preferred white balance setting. Because, you know, Raw captures don't record white balance. He doesn't mention that either. So we can assume he's shooting that Nikon D800E of his in JPEG mode.
And don't mention post processing. Peterson omits that too.
If you learn one thing from our Friday Slide Shows, it's that post processing is half the fun. It's only in post that you can see all the options your Raw capture contains. Move the Shadows slider or the Highlights slider, adjust the Clarity slider and the image is transformed in ways no correct exposure can deliver as a JPEG.
In fact, it's a little odd that someone who would argue for manual exposure would accept automatic JPEG conversion as the test of his camera settings.
Well, now you can see what fun we had going through this book. If you leave out enough information, you can argue that there is such a thing as a correct or preferred outdoor manual exposure for a JPEG. And this will matter to sports shooters or anyone on a deadline.
But for the photographer that wants to take advantage of what the blessings digital technology hath wrought, Understanding Exposure leaves a lot out.
Understanding Exposure by Bryan Peterson, published by Ten Speed Press, 176 pages, $26.99 (or $16.06 at amazon.com).