Tag Archives: Great Sand Dunes National Park

The Tonal Range Myth (or, Why I Don’t Use HDR)

Great Sand Dunes National Park No. 2

I’ve met a number of photographers who seem obsessed with translating the tonal range they see with their eyes into the images they make on paper.  For these folks, it’s almost a crime for an image to have areas of pure, featureless black.  Every shadow must have detail, and the failure to preserve detail in the shadows not only is a serious technical failure, it’s just about a sin against photography.  It probably comes as no surprise after viewing the image in this post, “Great Sand Dunes National Park No. 2,” that I’m not one of those people.

By way of background, when I say tonal range, I’m basically referring to the spectrum of tones available in a black and white photograph, from pure featureless black, through the full range of grey tones, up to pure featureless white.  Estimates seem to vary, but it’s probably fair to say most people agree that the human eye can perceive a wider tonal range than is able to be captured by most cameras.

The image in this post, for example, was captured as the sun was setting over Great Sand Dunes National Park in Colorado’s San Luis Valley.  As the sun went down, the tops of the dunes caught the last of the light, while the troughs of the dunes were in dark shadow.  With my eye, I could still plainly make out the details in the troughs – the texture of the sand, the patterns of ripples, etc.  But since my camera’s dynamic range – it’s ability to capture tonal range – was smaller than that of my eyes, the image rendered by my camera made the dune troughs much darker in comparison to the dune tops than how my eyes perceived them.

Several technical workarounds exist to address this situation.  One commonly used approach with digital photography is HDR.  HDR stands for High Dynamic Range, and essentially involves taking multiple images of a scene – for example, one exposed to get details in the highlights and one exposed to get details in the shadows – and combining them using computer software so that the final  image has detail throughout the tonal range.  As a result, the tonal range of an image captured with a camera can be expanded, for example to more closely approximate what the eye actually saw.

Now, I’m sure my explanation of HDR probably is giving it short shrift, and that there’s more to it than I’m letting on.  I wouldn’t know, because I’ve never felt the need to use it.

I like that cameras have a limited dynamic range.  It forces you to place your limited budget of tones right on what the most important part of the scene is – here, for example, the tops of the sand dunes.  Moreover, having the less important parts of the scene fall into the shadows forces you to compose wisely, so that you arrange the areas of highlight and shadow to emphasize the subject and create a pleasing composition.

To me, large areas of deep, featureless black can be a powerful compositional element of an image.  Here, for example, I think the deep blacks of the shadow areas add weight and substance to the implied bodies of the dunes, and set off the more delicate, sunlit strips of the dune tops.  Because these deep, black shadows flow right across to the sides of the frame, I also think they create a significant degree of left/right movement through the frame, allowing the eye to freely travel across the image.

Additionally, pure black looks great on paper.  High contrast images can pack a great punch, and deep, inky shadows shine (yes, shine) when placed up against bright white highlights.

I don’t have anything against HDR.  As with most technical aspects of photography, it’s a tool that does a job, and I’ve seen many images where HDR was employed to spectacularly good effect.  However, not every job requires this tool, and not every image requires a full range of tones, especially in the shadow areas.  It’s a myth, and I’m happy not to go along with it.

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