Monday, August 27, 2012

Evening Paddle, and Using A Graduate ND Filter

Capturing the range of light available at dawn or dusk can be difficult. There are a number of ways to work with this light, the first way is to shoot purely for the brightest parts of the scene. This is an appealing way to shoot, as it creates silhouetted objects in the darker parts of the image. On the other hand, that is not very helpful when you want to capture detail in the dark parts of the image.

The second way to capture the scene is to expose in the middle and try to recover the highlights and shadows in post production software. This is not ideal, because you will often hit a point where you cannot recover enough of the bright or dark parts in the image. This is just the nature of digital cameras at this time, with the average camera being able to capture 10-12 stops of light in RAW files. Even high end cameras, like the Nikon D800 capture 14-16 stops of light, and in a scene like the one above that is simply not enough.

The third way to capture a scene like this is to use an HDR technique. Some modern cameras can do HDR right in the camera, while others will require you to take a series of photos at different exposures and combine them later in post processing software. HDR would work well here, but that wont work if you want to capture moving subjects in your images. That brings us to the fourth way of capturing a scene like the one above, using filters.

The fourth way of capturing a scene like this where there is a large difference in the light in different parts is to use filters. In this case I used a set of graduated neutral density filters (Grad ND). Generally speaking grad ND filters are rectangular filters, take need to be placed in a holder. The filter holder gives you the ability to use several filters at the same time, which can be extremely helpful. For the image above, an 8 stop and 4 stop (12 stop total) filter were used to extend the dynamic range that the camera could capture. By using a grad ND filter I was able to block some of the light in the brighter parts of the scene, namely the sky, without making the foreground totally dark (click on the image for a better view). By using these filters I was able to use a shutter speed that would capture the people paddling through the scene (without blur), not loose detail in the foreground and not blow out the highlights.

For a shot like this one, using graduated neutral density filters was the best solution. None of the other methods would have captured the dynamic range and frozen the action in a single shot.