On ND filters

For my birthday last year, I was gifted with an ND grad (.6, i.e., two stops) filter.  I haven't used it very much in regular shooting, but a recent trip out to a local tourist trap provided some opportunities to use it.  I've been trying to refine a raw workflow, but my hardware is limited and it has been a bit of a struggle to produce images in a timely fashion.

Neutral density filters are useful for a variety of scenes.  An ND filter reduces the light hitting the sensor by some amount.  This is helpful for scenes with a wide dynamic range (e.g., a sunset) or when additional motion blur is desired.  In the former case, the filters are usually graduated so that the horizon can be set properly:  above the grade, light is reduced; below the grade it is transmitted without change.  This is the sort of filter I have, but it serves in both capacities because it is large enough to fit over a 52mm lens without touching the grade.

Images with discussion following the jump.

24mm f/2.8 @ f/11, 1/6s, ISO 100

The above image doesn't use the ND filter.  Particularly troubling for the effect we're going for is the highlight band in the top-right quadrant as the water cascades down over the stick wedged between the rocks.  The ND filter helps to mitigate some of the harshness of the highlight; combined with stopping down and a more aggressive highlight-recovery algorithm in raw development, we get something like this:

24mm f/2.8 @ f/16, 1/3s, ISO 100; .6 ND grad, handheld

The grad line is "inverted," as it were.  In a sunset, the scene above the horizon is bright while the scene below the horizon is dark.  The whole scene here is illuminated by a strong sunlight, but I wanted a darker affect on the water itself.  Lining up the horizon so it passed more light at the top allowed this.

In post I more aggressively filtered the highlights to try to get back some detail (further reducing the glare), added in a bit of blue by rebalancing around 4500K, and upped the green a bit to bring out the moss.  All in all, I'm willing to call it a success, although it's probably a fairly typical scene.

In retrospect, I wish I'd had the foresight to move the stick out of the way, and a minipod around to stabilize it a bit more.