'evening, Constable

Not really a trip out to this week, more of a quick dash. Early on Saturday evening I noticed the sky was rather dramatic, with a mixture of white clouds, darker rain clouds and still some areas of blue sky. So I quickly made the 15 minute drive to Curbar Edge to see if I could get some dramatically lit landscapes. With it being near to the longest day I knew I had a good hour or so in which to work, before the sun got too low. I have plenty of sunsets taken in this area so I was looking for late evening shots rather than sunsets.

By the time I got there the ratio of clouds to blue sky had increased, but there were still patches of blue sky, and the promise that there might be some strong sunbeams appearing between gaps in the clouds. Because of the increase in clouds the land itself was quite dark in relation to the sky. Exposing correctly for the sky, would almost certainly cause the land to be underexposed.

There are several techniques for dealing with this situation. About the only option for slide film photographers, is to use a graduated neutral density filter. This is dark at the top and gradually gets lighter and then clear at the bottom. This is used to make the sky darker so that that relatively low latitude of the slide film can encompass both the sky and the land. Colour negative film photographers have another string to their bow: they can use the extended latitude of the film. A straight print from the negative will either be correct for the sky or the land, but not both. But by dodging and burning during the printing stage the best result for both sky and land can be arrived at.

For the digital photographer, in addition to the graduated neutral density filter, there are three other ways to beat the problem.

The first way is to use a good solid tripod and make at least two, and preferably more, exposures of the same scene, each exposed differently. One could be exposed to show all the detail in the sky correctly (resulting in very dark land), one could be exposed to show detail in the shadow areas on the land (resulting in a blown out sky) and the third could be an in between exposure that is correct for the midtones in both sky and land. Then within a photo editing package various techniques are available to merge the three separate exposures together so that the correct exposure for each area of the scene is used.

If no tripod is available another technique can be used. A single compromise exposure can be made with a raw file. The raw file can then be developed three times using the fact that raw file developers can, in effect, give a slightly underexposed image, a slightly overexposed image and an in between image. The three resultant exposures can then be merged, as in the previous technique.

And finally, the way I usually do it: I take a single raw exposure making sure that the histogram of the file is 'exposed to the right', but without too much clipping of the highlights. Some clipping of white clouds is in fact essential, because, although I am shooting a raw file, the histogram I see on the camera screen after exposure is not in fact the histogram of the raw file, but the histogram of a jpeg thumbnail file which the camera produces and embeds with the raw file for review puposes. Now when I develop the raw file on my pc, I set the raw developer to 'recover' the clipped highlights, whilst at the same time not clipping the shadows. This will usually give me a fairly flat result with a well exposed sky and a fairly dark land. This file is then passed into my photo editor, as a 16 bit file, where final processing is performed. This final processing mimicks the 'dodging and burning' which would be used by the colour negative photographer during the printing stage. I use this technique because, as an ex wet darkroom person I understand dodging and burning and I want my digital 'dry darkroom' processing to be as similar as possible to my previous experience. The actual way I achieve the dodging and burning, is to use selection tools, with various amounts of feathering, to select specific areas, and then use the levels tool on the selection to get the optimum exposure level for that area.

A picture is worth a thousand words so here is a jpeg produced from my raw file before I have done the dodging and burning:



And now the result of a lot of dodging and burning:



Notice how I have also made the sky a bit more dramatic, by selecting it and applying levels to 'stretch' the histogram so that some mid grey areas have been darkened.

This technique can be overdone to the extent that some results can look more like paintings than photos. I try to avoid that, but maybe the above example is approaching that level. I do however like fairly dramatic skies and think that on this particular evening I got one or two lanscapes with skies that are reminiscent of those in Constable paintings: