GRADUATED NEUTRAL-DENSITY FILTERS
When a scene has extreme exposure differences, like a landscape where the sky is much brighter than the foreground, a graduated neutral-density filter helps you expose for both by putting the darker part of the filter over the sky.
The Heliopan screw-in graduated neutral-density filters are available in strengths from one to three stops, and filter sizes from 49mm to 77mm. The Grad ND 4X provides two stops of density in a standard, calibrated rotating mount with front threads. Estimated Street Price: $149.
Singh-Ray graduated ND filters are available in two "soft-step" and two "hard-step" models. The soft-step filters work for scenes with no distinct boundary between the light and dark parts. The hard-step filters are ideal for scenes where sky and foreground areas are separate, usually at the horizon. Estimated Street Price: $99 to $400.
Filters also can create a variety of special effects in your photos.
Tiffen produces nearly every kind of special-effects filter you could ask for, from Fog models that mimic the look of natural fog to Glimmerglass, which softens fine details while adding a mild glow to highlights and reducing contrast. The company also offers filters for black and white, contrast control, tone control and color. Estimated Street Price: Varies.