Dynamic Range and your Digital Camera

Dynamic Range

OK, the details about dynamic range get a little tricky. But here's my favorite analogy: You know how on a really bright day, if you look at a scene, say a house, with the bright sky behind it, it takes your eyes a few seconds to “adjust” to the point where they start to see the details of the house in the shade? But eventually you begin to see the door, and the windows, and even the shrubs in the flowerbed.

This lack of response to contrasts happens to cameras too – film and digital both. Film has a better range of brightness just by nature of the way it’s made. Negative film has better range than slide film.

Most digital cameras, I’ve found, are similar to slide film, except for possibly one type of shot – but one that is critical for landscape photographers.

It's the landscape scene with the landform or subject against an overcast or partially cloudy sky. What happens in most cases, is the sky gets "blown out" if you expose for the shadow areas. Blown out means that there is no picture information there at all – no colors, no nothing. This is not good, because if there’s no information there, you can’t do anything to fix the image afterwards.

If you expose for the sky, the shadows are to dark. If you expose for the shadows the sky is blown out.

All this makes exposure for these scenes with a digital camera a little more tricky than you may be used to. I’m a big believer is making the photo as much in the camera as you can. Photoshop is great, but too much tweaking breaks down your image and can cause all sorts of ugliness. So if just like film, you take an accurate exposure, with all your filters etc. at the time of shooting, your final image will just be that much better.

So, before I started on my soap box there, my best fix is to use a graduated neutral density filter for my Nikon D70, that decreases the exposure for the sky by a several stops (depending on the filter used).

Cokin makes a good one – it’s a square piece of plastic that fits into a special holder. The P Series fits most digital SLRs like theNikon D70.

However, if you have a point & shoot digital camera, you may have trouble finding a proper filter to fit on your lens. My Olympus 5050 has an optional extension ring (CL1-A) that makes it possible to use regular screw mount 55 mm filters. And Cokin makes adapters for this size ring, so you could get the 55mm adapter ring for Cokin’s system, and get the filter holder and the filter itself. It’s a bit cumbersome, but worth it – especially for landscape shots.

Next, to Depth of Field - quite a surprise!

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