- published: 20 May 2013
- views: 1762371
In optics, an 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. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp for things at the correct distance. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time). In the human eye, the pupil is the aperture.
An optical system typically has many openings, or structures that limit the ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point.
Happiness is somewhere i have been before-
A blurry photograph that i have since ignored.
I'll carefully adjust the aperture once more,
Until i set the record straight.
I'll brush aside the dim, make room for the bright.
I'll be an editor, no, a curator of light.
I'll let my better angels always set me right,
Until i even out the score.
Until i even out the score.
God, it has been quite a year-
I've lived a little bit and i've died a little more.
I know that i've asked it before,
But please let the scale tip here in my favor.
What was once the sweetest melody i've heard
Is now a memory reduced to little words.
I'll tune the orchestra and play the overture,
Until i pinpoint every note.
Give me the heart of an archeologist,
That i may dig until i prove that i exist.
A subterranean cathedral in my midst,
Where echos come to rest.
Where echos come to rest.
Is this where echos come to rest?
God, it has been quite a year-
I've lived a little bit and i've died a little more.
I know that i've asked it before,
But please let the scale tip here in my favor.
Until i set the record straight,
Until i set the record straight,