• Optic
  • Larger stops can cause the intensity reaching the film or detector to fall off toward the edges of the picture, especially when, for off-axis points, a different stop becomes the aperture stop by virtue of cutting off more light than did the stop that was the aperture stop on the optic axis. (wikipedia.org)
  • retina
  • The high pigment content blocks light from passing through the iris to the retina, restricting it to the pupil. (wikipedia.org)
  • The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. (wikipedia.org)
  • This may be due to the fact that the reflection of one's image in the pupil is a minuscule version of one's self The pupil is a hole located in the centre of the iris of the eye that allows light to strike the retina. (wikipedia.org)
  • These include having a larger eyeball, a larger lens, a larger optical aperture (the pupils may expand to the physical limit of the eyelids), more rods than cones (or rods exclusively) in the retina, and a tapetum lucidum. (wikipedia.org)
  • lens
  • An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide "color-blind" animals with a way to distinguish colors. (pnas.org)
  • A simple cosmetic solution is a specialized cosmetic contact lens with an artificial pupil aperture. (wikipedia.org)
  • For a pupil size of ≥ 3 mm, distinctive MTF peaks were observed for all lenses: two peaks for the extended depth of focus and bifocal lenses with +1.75 and +4.00 diopters (D) addition, respectively, and three peaks for the trifocal lens with +1.75 and +3.50 addition for intermediate and near vision, respectively. (escrs.org)
  • For small pupil apertures, the MTF peaks for the far and intermediate focal distances of the trifocal and extended depth of focus lenses overlap, but the trifocal lens presented an additional MTF peak for the near focal points. (escrs.org)
  • For example, in a telescope, the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). (wikipedia.org)
  • In addition to an aperture stop, a photographic lens may have one or more field stops, which limit the system's field of view. (wikipedia.org)
  • The centre of the diaphragm's aperture coincides with the optical axis of the lens system. (wikipedia.org)
  • A lens that is focused onto the point source will have optics that change the spherical wave front into a planar wave before it passes through the pupil or aperture stop. (wikipedia.org)
  • These two strata are continuous with each other at the cup margin, which ultimately overlaps the front of the lens and reaches as far forward as the future aperture of the pupil. (wikipedia.org)
  • telescope
  • These objects, being more difficult, can offer dramatically different images depending on the telescope aperture and sky quality. (uv.es)
  • One then speaks of a telescope as having, for example, a 100-centimeter aperture. (wikipedia.org)
  • An astronomical telescope requires a large pupil because it is designed to be used for looking at dim objects at night, while a microscope will require a much smaller pupil since the object will be brightly illuminated. (wikipedia.org)
  • thus
  • 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). (wikipedia.org)
  • The location of the exit pupil thus determines the eye relief of an eyepiece. (wikipedia.org)
  • It is thus possible to deduce the point-spread function of the out of focus point source as the Fourier transform of the pupil function. (wikipedia.org)
  • brightness
  • The aperture stop is the aperture setting that limits the brightness of the image by restricting the input pupil size, while a field stop is a stop intended to cut out light that would be outside the desired field of view and might cause flare or other problems if not stopped. (wikipedia.org)
  • In general, these structures are called stops,[citation needed] and the aperture stop is the stop that primarily determines the ray cone angle and brightness at the image point. (wikipedia.org)
  • typically
  • The maximum pupil size of a human eye is typically 5-9 mm for individuals below 25 years old, and decreases slowly with age as shown as an approximate guide in the table below. (wikipedia.org)
  • dilate
  • Many fish have neither, and, as a result, their irides are unable to dilate and contract, so that the pupil always remains of a fixed size. (wikipedia.org)
  • Furthermore, the pupil will dilate if a person sees an object of interest. (wikipedia.org)
  • passes
  • The size and shape of this disc is crucial to the instrument's performance, because the observer's eye can see light only if it passes through this tiny aperture. (wikipedia.org)
  • refers
  • In contrast, the terms direct and consensual refers to the side where the light source comes from, relative to the side of the reacting pupil. (wikipedia.org)
  • displaystyle
  • The light may also be attenuated differently at different positions ( u , v ) {\displaystyle (u,v)} in the pupil, sometimes deliberately for the purpose of apodization. (wikipedia.org)
  • Such change in amplitude of the light wave is described by the factor A ( u , v ) {\displaystyle \mathrm {A} (u,v)} . The pupil function is also directly related to the point spread function by its Fourier transform. (wikipedia.org)
  • R , {\displaystyle \mathrm {P} (u,v)=0,\forall u,v:{\sqrt {u^{2}+v^{2}}}>R,} where R {\displaystyle R} is the pupil radius. (wikipedia.org)
  • lenses
  • Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system. (wikipedia.org)
  • light rays
  • A clear vial of milky fluid can also be used to visualize the light rays, which appear as an hourglass shape converging and diverging as they exit the eyepiece, with the smallest cross-section (the waist of the hourglass shape) representing the exit pupil. (wikipedia.org)
  • It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil. (wikipedia.org)
  • limits
  • in practice these conditions may not be realized, and the images projected by uncorrected systems are, in general, ill-defined and often completely blurred, if the aperture or field of view exceeds certain limits. (wikipedia.org)
  • rays
  • The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. (wikipedia.org)
  • If an aperture is wide, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. (wikipedia.org)
  • A narrow aperture admits uncollimated rays, resulting in a sharp focus only for rays coming from a certain distance. (wikipedia.org)
  • Only rays which pass through this virtual aperture can exit the system. (wikipedia.org)
  • image
  • The bizarre off-axis pupils of these animals can be understood as an adaptation that maximizes spectral information, even at the expense of image acuity. (pnas.org)
  • This means that a narrow aperture results in an image that is sharp for things at the correct distance. (wikipedia.org)
  • radius
  • Posters and online campaigns promoting the search for Madeleine use the word "Look" with the first "O" in the word being drawn in the shape of a coloboma radius extending from the pupil at the 7 o'clock position. (wikipedia.org)
  • Therefore
  • At this stage the pupils do not remain completely still, therefore may lead to oscillation, which may intensify and become known as hippus. (wikipedia.org)
  • Therefore, to have the same exposure at this larger aperture as at the previous aperture, the shutter would be opened for half as long (i.e., twice the speed). (wikipedia.org)
  • daylight
  • the pigment responsible of the greater eye sensitivity during the night) activation, and our eyes will work as under daylight conditions, but with a more dilated pupil. (uv.es)
  • determines
  • The distance of the exit pupil from the sensor plane determines the range of angles of incidence that light will make with the sensor. (wikipedia.org)
  • Sometimes
  • Sometimes this function is referred to as the generalized pupil function, in which case pupil function only indicates whether light is transmitted or not. (wikipedia.org)
  • small
  • It can be seen by shining the beam of a small bright light penlight through the pupil from the periphery of a subject's vision. (wikipedia.org)
  • wide
  • In the dark it will be the same at first, but will approach the maximum distance for a wide pupil 3 to 8 mm. (wikipedia.org)