Strategy exposed: See the light for good photos

By Joe Kashi, for the Redoubt Reporter

Now that “Black Friday” and “Cyber Monday” sales have expired, along with many credit cards, let’s return to getting the most out of your existing camera gear.

Used properly, many midtier and upper-tier cameras introduced over the past three or so years are more than adequate for most professional work. That’s just as well, because unless you’ve somehow qualified for top honors on Santa’s 2014 “nice” list, you may need to wait until 2015 for your upgrade to the latest and greatest.

It wasn’t so long ago that all cameras were completely manual devices with absolutely no electronics, gadgets, features or helpful suggestions summoned at the press of a button. No auto-exposure, no autofocus, no handy scene modes, no quick previews on the rear LCD screen — no rear screen at all, for that matter. The only onboard computing hardware was a knowledgeable Model 1 Mark I human brain.

Despite such “limitations,” a very high percentage of the iconic photographs in our visual repertoire were made with those “simple” mechanical cameras.

Misty nostalgia aside, those weren’t good ol’ days compared to the superb capabilities of modern digital cameras and lenses. However, the very limitations of those manual cameras forced users to become knowledgeable and to first think through the desired final result and how to accomplish it.

Setting aside for the moment more contentious issues like composition and choice of subject, effective photo technique depends on proper exposure and accurate focus. Marvelous as our modern, auto-everything cameras might be, they remain susceptible to traditional exposure errors, particularly when set to factory defaults that most users neither understand nor even know.

In past issues, we’ve discussed setting ISO sensitivity, avoiding subject motion and camera shake through fast-enough shutter speeds, and using the optimum settings for each of your lenses. It’s time to put all of that together and look at how your camera determines the overall exposure.

Modern digital cameras determine exposure somewhat differently than the handheld meters in common use 40 years ago. Those handheld meters measured the light directly striking the meter, not the intensity of the light projected by a lens onto the film or sensor, as is now the norm.

As a result, those handheld light meters and lenses had to be carefully and individually calibrated together for best results. Then, it wasn’t a matter of simply unboxing a new camera, inserting the batteries and going forth to effortlessly produce timeless art.

Manual exposure meters were crude compared to the effective, sensor-based metering modes now built into good digital cameras. Most handheld exposure meters simply read and averaged all of the light reflected from a broad subject. While that sort of exposure determination might provide a starting point, it was easily fooled by subjects that were brighter than average, such as a sunny beach, or darker than average, such as a spruce forest.

If no exposure compensation was made for those nonaverage subjects, the exposure was off, sometimes seriously so. Nonaverage subjects remain a common exposure problem with modern digital cameras, particularly when used in an averaging meter mode. That’s why a manually set exposure compensation dial is a prominent control on better digital cameras. Acquire subject, engage Model 1 Mark 1 brain, determine and set correction, and fire for effect. It’s Christmas, so be sure you don’t accidentally acquire Santa’s sled as a target or you’ll be on the “naughty” list permanently.

Spot metering is another traditional exposure method that’s carried over into modern digital cameras. It’s well suited to dealing with nonaverage situations but requires some care and patience in use. We’ll discuss how to use your camera’s spot-metering exposure method in a later article.

Averaged exposure modes have another significant failing. They tell the user nothing about the brightness of either the highlights or of the shadows, both of which remain critical elements of proper exposure. Too much exposure and highlight detail is irretrievably lost. Too little and shadows become impenetrably black.

Traditional negative films, particularly color negative films, were not as susceptible as digital cameras to blown highlights caused by severe overexposure. In contrast, underexposing shadow areas could be fatal with negative films. As a result, the better practice was to somewhat overexpose color negative films when in doubt. Color transparency (slide) films worked in an exactly opposite manner. Slide films had little tolerance for overexposure but a modest degree of underexposure was well tolerated. Good practice with color slide film was to slightly underexpose, giving deeper, richer color.

Digital photography still requires precise exposure, but it’s more akin to color slide film in that slight underexposure seems less a problem than overexposure with most cameras, especially when saving images in an RAW file format.

Personally, I’d rather deal with some measure of digital underexposure because it seems easier to retrieve good detail from underexposed shadows than from blown highlights. There’s more digital noise in underexposed images brought up to the appropriate brightness level but, unless truly severe, it’s largely correctable with a program like DXO Optics 10.

Some other useful exposure metering methods have also found their way into modern digital cameras. For example, later film cameras incorporated internal exposure meters that were “center-weighted.” This exposure method determines exposure based on the brightness of the central portion of the frame, making the reasonable supposition that most people put their subject in the middle of the frame and want the subject to be normally exposed.

Most cameras also have a matrix exposure mode, although it’s likely called something else. It’s typically the default-metering mode to which most cameras are set at the factory. With matrix metering, the camera measures several small areas of the subject, likely metering in the process some shadow areas, a highlight or two, and the main subject’s brightness. By taking all of these different brightness areas into account, matrix metering is programmed to set what it believes to be the best compromise exposure.

Many matrix-metering arrangements can be customized to some extent, allowing the user to specify the size and number of measurement areas. I’ve tended to shy away from matrix metering because, in my limited experience, it seems to overexpose images, the worst sin with digital images as it is with politicians’ images.

A bit of experience will show whether your camera’s matrix metering tends toward perfect exposure, underexposure or overexposure. Once its programmed bias is known, you can revert to that handy exposure compensation dial that we mentioned above, dial in a correction factor and be reasonably confident of good results in most circumstances.

I’ll often use the center-weighted exposure modes on my Pentax and Olympus cameras when I’m causally shooting average subjects. It’s fast and usually accurate enough in those circumstances. Minor problems can be fixed by post-processing the RAW files. More complicated exposures call for metering several spots and then mentally determining the best overall exposure.

JPEG images have little latitude for later correction with post-processing software, so JPEG exposures should be as precise as possible for best results. Although most people tend to think of JPEG files as the easy default, that’s not really the case when you want a quality end product. In such instances, using RAW files and post-processing them is actually easier and more reliable because of RAW’s greater latitude for inaccurate exposure. Significantly overexposed JPEG images are generally unusable and unrecoverable, so it’s best to err toward slight underexposure if you’re using JPEG.

Local attorney Joe Kashi received degrees from MIT and his law degree from Georgetown University. He has published many articles about computer technology, law practice and digital photography in national media since 1990. Many of his technology and photography articles can be accessed through his website, http://www.kashilaw.com.

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