Using Partial Dynamic Range

From Ansel Adam’s Zone System to today’s digital algorithms that make the best use of available dynamic range, is there a place for using a limited dynamic range? Using a part of available dynamic range can provide wonderful artistic images. These can be poetic, melancholic, dreamlike, dramatic or even surreal.

 

Marsh

(A photograph of marshy land. The way grass stands out in front of the distant trees is eye catching. This photograph uses almost whole of the available dynamic range but can the effect be improved upon?)

 

What exactly is Dynamic Range?

The range of maximum and minimum exposure values that a camera can capture (Exposure Values & Exposure Compensation). A range of 12-14 exposure values is common in today’s digital cameras. A camera with a dynamic range of 12 exposure values can capture a dark area which is 12 EV lower than the brightest it can capture. A histogram of a photograph that uses the complete available dynamic range is spread across the whole of the graph area. (Understanding Histograms)

 

Limiting the Dynamic Range

This is opposite to what people usually do. By limiting the dynamic range various artistic expressions can be achieved. The high key images and low key images are two such examples. In this short articles, I’ll explain how images can be further improved by creatively using a limited dynamic range.

 

Some of the methods to limit the dynamic range :

1. Experiment with double exposure (controlled fogging of the film?)

Foggy Marsh

(Nikon camera with 135mm lens at f/5.6, ISO 200. Post-processed in Affinity Photo.)

The aim in the photograph was to limit the exposure in such a way that the bright areas retain a shade of grey which intensifies a feeling of fog and coldness, and on the other hand expose the grass in a manner that there are no overly dark spots.

In film days, the technique was to use double exposure. The first exposure used to be of an unfocused smooth background which was underexposed and the second exposure used to be of the actual subject (also a little underexposed). These two frames on getting overlapped produced low contrast images with limited dynamic range. The technique was used even by the old masters like Ansel Adams in some his iconic landscape images.

In this particular image, I was using a digital camera and the easier way out was to use layers in post processing. The first layer was a dark grey layer generated from an old photograph and then the second layer of actual image (which was also underexposed while capturing) was merged into it. Underexposing the image reduces the time required in post-processing and creating the composite (overlayed image).

Here is the histogram of the above photograph. The dynamic range is limited to central part of the histogram.

Histogram - limited dynamic range

Here is another example of a photograph created using the above technique. The only difference is that the layer which was used had a cyan hue to it. That did the magic!

Tree in Fog

 

2. High and Low Key Images

I have already written an article on it. Do check it out – Low and High Key

Just a reminder here. The low key images are dark but have character in the shadow areas. Similarly the high key images are bright but not so overexposed that the main elements end up being without any information. Do read the article that I have provided the link too. That has some more details on how to create impressive high and low key photographs.

 

3. Use natural haze

Fog, dust, rain, smoke and anything that reduces visibility can be useful in limited dynamic range photographs. In fact, the photographs in the above examples were also helped by presence of some amount of fog.

Snow and Fog

 (Maini’s Hill Cottages – photographed from some distance using a mild telephoto lens. The fog present helped in creating this low dynamic range image)

This photograph of our cottages would have been spoilt, had I worked on the curves tool to bring out the blacks. The left part of the photograph is clearer than the far end of the cottages due to comparatively less amount of fog between the lens and the subject (in comparison to the fog between the lens and far end of the cottage).

Using the first technique of double exposure or overlaying, would not have worked so well here, because that would have limited the dynamic range equally all across the cottages, thereby making the effect artificial.

 

4. Shoot against the sun

This is a difficult thing, I agree. If your lens can handle it and if you can avoid obvious halos, then do give it a try. The bright light from the sun creates an overall haze and reduces the contrast. This can be used creatively for low dynamic range images.

Sunrise

(f/8 at 1/125 sec. Evaluative metering. Post-processed and cropped on Affinity Photo, without any major changes)

The surreal effect on the mountains was enhanced by shooting against the light (Contre-Jour). The cloud cover balanced the composition while adding some amount of character to the sun.

 

5. Use a relatively higher ISO and expose to the right (ETTR) – A large dynamic range is achieved by compression of minor difference. In the kind of photographs, I am discussing here, this compression may look like banding or sudden change in color or light gradient. By using raw files with a higher ISO (usually lower side of middle readings, actually it depends on your camera) and ETTR, the effects of this compression are reduced but at the cost of dynamic range, but then, that does not matter here since we are already trying to utilize a small part of the range. While post-processing, correct the exposure. This technique will have the added advantage of reducing the noise.

 

6. Post process and use the curves tool

For details on using the curves tool, check out this article – Curves Tool at your service

The curves tool is a very strong aid available now which can be useful to reduce the contrast in the images. Try an ‘inverted S’ curve to reduce the contrast.

Raising or lowering the overall curve can also help in reducing the perceived dynamic range (by lightening or darkening the whole image). Raising the curve gives a better perception than lowering it, especially if you are planning on displaying the image electronically.

Mountain Landscape

(A mountain landscape. The curves tool was used in post-processing. By raising the curve a little, the overall dynamic range appears to be constrained to a small region. This is not exactly limiting the dynamic range but still works fine in many cases)

 

So, go grab your camera and try out capturing low contrast images. Use the dynamic range extending over just a few EVs and see the art come alive. Use this method to express your own feelings.

 

 

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