If you ever tried to photograph a high contrast scene such as a late afternoon landscape or sunset you know that it is almost impossible to get a good exposure of the sky along with detail in the foreground or shadow areas. One way to get around this problem is by using high dynamic resolution (HDR). This process requires photo software to merge several photos, each exposed for a particular section of a scene, into one photograph that is properly exposed in all areas. HDR, however, requires more screen time, something I would gladly reduce.
Neutral density graduated filters provide an alternative for capturing high contrast settings. By sliding the filter through its lens holder to the point just before any of the foreground starts to darken you will reduce the intensity of the sky so that you can get a more evenly exposed photograph.
I recently purchased a set of Cokin P series filters (H250A). The kit contains the filter holder and three neutral density graduated filters: 121L, 121M, and 121S. The first reduces exposure by 2, the second by 4, and the third by 4 with a more gradual shading from clear to neutral gray (the adaptor ring that connects the filter holder to the lens is extra). The total cost was $105, before tax.
I took a few photographs so you can see their effects (I made no processing adjustments to the photographs, other than applying lens correction to minimize distortion). The photographs were taken in mid-July at about 4:30PM. The first photograph was taken without a filter. Here, I exposed to the right (in this case 1/25 @ f22, ISO 100)–only the partial disk of the sun is overexposed.
In the next photo I used the 121L (ND2) filter (1/20 @ f22, ISO 100). Notice that the sky is a deeper blue and there is somewhat greater detail in the trees’ foliage.
The last photo shows the same scene with the 121M (ND4) filter (1/20 @ f22, ISO 100). Here the sky is darker still, yet with even greater detail in the trees’ foliage. You can also see that I did not lower the filter quite enough, as there is a lighter sky immediately above the trees. Had I lowered the filter more I would probably have even greater detail in the foliage.
Since landscapes are best shot at dawn and dusk, these filters should enable me to produce images with less contrast and more detail. Though I do like landscapes in their own right, I plan to shoot more of these to illustrate the habitats of my bird photographs. By so doing I anticipate providing greater context for describing the birds and the state of their respective populations over the past 30 or more years.
If you have been using neutral density filters in your work I would be happy to hear about your experiences with them.