Using EXIF for Troubleshooting Image Problems
Back in the old days, photographers often carried a notebook to record details regarding the shots they took. Nowadays, those details are digitally burned into every image we take. But such details can be both a help and a hindrance when troubleshooting image problems.
Photographic exposure lends itself to description by means of basic equations utilizing a few simple variables. If we hold ISO sensitivity constant, exposure is controlled by just two settings, shutter speed and aperture. Throw in focal length, and you can boil down each image to a collection of just these three values. Serious photographers have always been expected to be able to quote such data on demand when asked about their work.
I remember trying to learn how to take better photos. Yes, I'm old enough to have learned with film and converted to digital only once it became practical to do so. Back then, I really couldn't see the results of my labors until I got the developed film back from the lab once I got home. Sometimes I was pleased, and sometimes not. When looking over each image, it was frustrating not knowing exactly what I did to cause that result. Some days had passed since I shot those images, and I couldn't easily recall the details for each shot. If a shot came out well, it would have been great to know how I did it so I could repeat my successes. If a shot came out less than optimal, it would have been great to know what caused it so I could avoid my failures. And yet there wasn't any easy way to know.
At times, I tried jotting relevant details down in a small notebook but that was cumbersome. With a notebook in one hand and a pen or pencil in the other, I had no hands left for the camera gear. And as soon as I put the notebook down, I would become absorbed in taking photos and the notebook would go unused. I often ended up with lengthy blank stretches in my note taking. At one point I tried a small handheld tape recorder that I could operate one handed, but that proved awkward for other reasons. I just couldn't get used to speaking into my hand like a secret agent when other people were around. I guess today everyone has a mobile phone and other gadgets they can talk into and resemble spy gear, but not back then. I felt seriously out of place. As such, it took me a long time to learn my craft, lacking what I had been told were important metrics.
But just how important are such details? Exposure isn't just the camera settings. There's clearly more to it than that. Simple ambient brightness obviously has a significant bearing on exposure. It takes a longer exposure or wider aperture to get a good exposure in dim light when compared to broad daylight. Yet few photographers I've ever encountered logged any form of absolute EV setting with the other data they recorded. The use of filters, extension tubes, teleconverters and other accessories also influence light transmission on its way to forming an image. Similarly, focal length only tells part of the story regarding image framing. Subject distance influences not only subject size, but also the relative size and perspective of that subject to everything else in the frame. But I've never heard of anyone pulling out a tape measure to collect such details in the field.
These days, digital cameras record vastly more information than we ever could back in the days of film photography. The amount of EXIF metadata recorded by modern digital cameras as part of each image is quite extensive. Yet no camera can record every facet of information that would be needed to statistically describe an image and how it was taken.
Does this mean that such efforts are ultimately futile, that recording such details serves no purpose? Of course not. Within the limits of situation and circumstances, metadata details can indeed shed light on why things may have gone awry when images don't come out as expected. Or why they worked out so well when the results are pleasing. Hopefully, by comparing such details, you'll be able to have more occasions when the latter happens than the former. That's the aim, after all — to learn and improve at photography.
But photography is both a science and an art. Not everything lends itself to statistical analysis. With the ease of access to such metadata today, I find some photographers too concerned with such details. A good image is more than just a good exposure. The creative side of photography may have "rules" such as the rule of thirds, but these aren't really rules in the literal sense. They serve merely as conventional templates on how to organize the parts of an image. Many times they work, sometimes they don't. There simply can't be a substitute for the eye of the photographer and the esthetic sense that goes along with it. Sometimes troubleshooting an image problem may have nothing to do with the collection of numbers that describe it and no amount of study of such details can tell you how to improve it. One of the most important things to learn about photography is that it goes beyond such rational analysis. Good photography touches the soul.
I'm not saying not to make use of the EXIF data. Had I had it back when I was first starting out, I'm reasonably sure it would have accelerated the learning process. Or at least it would have cut down on my frustration over not having such data.
But sometimes, it's better to ignore the EXIF data and just look at the image. Follow your feelings, not just the numbers.