This article describes managing digital image capture to achieve optimal, or at least intended, dynamic range and how to determine the most appropriate camera range settings to accomplish this.
The Zone System
The simplest takeaway from the oft-misunderstood Zone System, is that an image should be exposed to utilize most or all of the range from black to white, without unintended clipping of near-whites, or blocking up of near-blacks. If the image does not incorporate the full dynamic range in a scene, the photographer should have done this by intent.
In digital photography, the most commonly recommended camera settings involve protecting detail in the brightest parts of the image, and correcting everything else in post-processing.
Errors that Affect Image Quality
It’s true that the biggest image-killer is over-exposing the whites, preceded only by the errors of blur and incorrect focus. Please don’t make the mistake of assuming that these last two items are not relevant to this article: camera settings can cause camera-blur, or motion-blur, as well as shorter or longer than desired focal zones. Other errors that are difficult, if not im- possible to correct in post-processing include noise from excessively high ISO settings, and noise in the darks from too short an exposure or too restricted an aperture. High dynamic range cameras and excellent noise reduction software reduce the impact of these problems, but they do not eliminate the importance of using settings that capture cleaner images. In other words, it’s important to “get it right in the camera.”
The opening paragraphs of this article may be a restatement of the obvious to experienced photographers, but they tend to be an eye-opener to shooters who became serious about photography after the digital revolution. “You mean there is more to camera settings than shooting in Aperture Priority, and adjusting exposure bias to avoid highlight blowouts?” Yes, there is. The next question is: how to best determine optimal camera settings, including ISO, white point, aperture, exposure and even choice of lens, in the digital age? Is an old fashioned handheld light meter still needed, or can the camera’s metering be trusted? Is there a third method that should be considered?