Explore the
Universe

Step 1 of 2

Create your profile to get all your Alpha Program notifications in one convenient location.

The Basics

Must contain at least 8 characters, an uppercase character, a lowercase character, a number and a symbol.
By joining the Alpha Universe community, you agree to the Terms and the Sony Electronics Inc. Privacy Policy and certify that you are a U.S. resident. (CA Privacy Notice).
Next

Personalize Your Profile

Step 2 of 2

Create your profile to get all your Alpha Program notifications in one convenient location.

Your Specialty *

(Select All That Apply)


I am a... *

(Select All That Apply)


(Optional)


What kind of camera(s) do you shoot with? *

(Select All That Apply)

The Techtionary is an interactive tool to explore and learn about photography and terms and technology. Search for a term, or just explore. Click on a term to learn more about it, including links to specific articles and deeper information.
Neutral Density (ND) Filter | a neutral-density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving no changes in hue of color rendition. It can be a colorless (clear) or grey filter, and is denoted by Wratten number 96. The purpose of a standard photographic neutral-density filter is to reduce the amount of light entering the lens. Doing so allows the photographer to select combinations of aperture, exposure time and sensor sensitivity that would otherwise produce overexposed pictures. This is done to achieve effects such as a shallower depth of field or motion blur of a subject in a wider range of situations and atmospheric conditions. For example, one might wish to photograph a waterfall at a slow shutter speed to create a deliberate motion-blur effect. The photographer might determine that to obtain the desired effect, a shutter speed of ten seconds was needed. On a very bright day, there might be so much light that even at minimal film speed and a minimal aperture, the ten-second shutter speed would let in too much light, and the photo would be overexposed. In this situation, applying an appropriate neutral-density filter is the equivalent of stopping down one or more additional stops, allowing the slower shutter speed and the desired motion-blur effect.
A
Aperture
Aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. More.