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Topic: Entrance pupil

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	Lens hoods
		The red bars mark the lens entrance pupil, which is the image of the aperture stop (the fl bars) seen by an observer looking into the lens from the front.
		Here, the lens hood completely obscures the entrance pupil (the small circle in the circle plot) and no light is passed on to the image corner.
		A nice description to figure out the optimum length, by inspection of the exit pupil rather than the entrance pupil, is available as a pdf file [1].
	www.vanwalree.com /optics/lenshood.html (2418 words)

	MICROSCOPE - LoveToKnow Article on MICROSCOPE (Site not responding. Last check: )
		The principal rays, which on the object-side connect the object-points ~sith the centre of the entrance pupil, intersect the axis on the image-side at the centre of rotation M of the eye.
		The centre of the entrance pupil is the point of intersection of the principal rays; and it is therefore determinative for the perspective representation on the plane focused for.
		The distance of the centres of the semicircular entrance pupils and their distance from the object regulates the difference of the two perspective representations, which are presented one to the right eye and one to the left.
	23.1911encyclopedia.org /M/MI/MICROSCOPE.htm (22295 words)

	Pupil - Wikipedia, the free encyclopedia
		In humans and many animals (but few fish), the size of the pupil is controlled by involuntary contraction and dilation of the iris, in order to regulate the intensity of light entering the eye.
		The reasons for the variation in shapes are complex; the shape is closely related to the optical characteristics of the lens, the shape and sensitivity of the retina, and the visual requirements of the species.
		In strong light, the pupil constricts and is small, but still allows light to be cast over a large part of the retina.
	en.wikipedia.org /wiki/Pupil (695 words)

	Stops and Apertures
		The entrance pupil is the opening an observer would identify as the limitation on the solid angle of rays diverging from an on-axis object point, i.e.
		The angular field of view is the angle formed by the edges of the entrance window at the on-axis position of the entrance pupil.
		The exit pupil therefore is the image of the objective formed by the eyepiece.
	electron9.phys.utk.edu /optics421/modules/m3/Stops.htm (1771 words)

	LENOX - LoveToKnow Article on LENOX (Site not responding. Last check: )
		The centres of the entrance and :xit pupils are thus the intersections of the principal rays.
		If the entrance pupil is narrow, then the section NO, in which the vignetting is increasing, is diminished, and there is-really only one division of the section M which can be reproduced, and of the section P which cannot be reproduced.
		If, for instance, the entrance pupil is imagined so small that only the principal rays pass through, then they project directly, and the intersections of the principal rays represent the projections of the points of the object lying off the plane focused for.
	43.1911encyclopedia.org /L/LE/LENOX.htm (8903 words)

	Photographic Lenses Tutorial
		This virtual image is called the entrance pupil.) Analogous to the entrance pupil is the exit pupil, which is the virtual image of the aperture as seen though the rear elments.
		The pupil magnification is the ratio of exit pupil diameter to the entrance pupil diameter.
		The essence of the approximation is the distinction between the axial distance to plane of the entrance pupil and the distance along the hypotnuse to the edge of the entrance pupil, which is the really correct form.
	www.faqs.org /faqs/rec-photo/lenses/tutorial (5148 words)

	Camera Optics Subassembly (COSA)
		However, the used area of the entrance pupil is limited to an approximately rectangular area 20 mm x 32 mm, as sketched in figure3.11.
		Reminder: the entrance pupil and pupil of the ground imager are not physical apertures, but relate to the image shape at the entrance and within the ground imager.
		The pupil of the ground imager is not physically defined by an aperture near the Scrambling Window, but by the aperture of the diffraction grating in the spectrometer.
	envisat.esa.int /dataproducts/meris/CNTR3-1-2-3.htm (1044 words)

	Locating the center of the entrance pupil of an eye after pupil dilation - Patent 5740803
		When the reference image is positioned on an image of the anatomical landmark appearing in the second image, the center of the undilated pupil referenced to the reference image defines the center of the entrance pupil of the eye.
		Entrance pupil 22 appears at a position that is 3.05 millimeters from interior surface 14 (measured along optical axis 18) or 0.55 millimeters closer to interior surface 14 than natural pupil 20.
		Recall that the center of entrance pupil 22 (i.e., prior to dilation) is optical axis 18 in FIG.
	www.freepatentsonline.com /5740803.html (3360 words)

	Reflective optical triplet having a real entrance pupil - Patent 4733955
		Because the entrance pupil of the system is real and not virtual, the aperture stop of the system is coincident with the entrance pupil, resulting in a significant reduction in beam wander about the front of the optical system.
		The real entrance pupil of the system also allows the system to be utilized for applications where it is required that the system view distant objects by means of a small viewing port, window or object space scan mirror.
		A typical requirement of an imager is that the entrance pupil of the imager match the relatively small exit pupil of the focal telescope.
	www.freepatentsonline.com /4733955.html (3954 words)

	Modeling off-axis vision - I: the OPTICAL effects of decentering visual targets or the eye's entrance pupil
		The close correspondence between the center of the natural pupil and the visual axis indicates that the eye's pupil is located to provide best image quality in the fovea.
		Although the geometrical center of the eye's entrance pupil may be decentered, the effective pupil center (the central moment of the SCE-weighted decentered pupil) will be approximately anchored near the peak of the SCE (and hence near the center of the natural pupil).
		The angular horizontal disparity (the ordinate in Fig.
	research.opt.indiana.edu /Library/ModelOffAxisI/ModelOffAxisI.html (8512 words)

	1978 IPS Perimetry Standards
		Since we often cannot control pupil size in the clinical environment, the least we can achieve is to specify luminance at the center of the entrance pupil of the eye, and to request the examiner to record this luminance and the entrance pupil size at the time of the measurement.
		Luminance at the center of the entrance pupil of the eye should be specified for defined operating conditions of properly centred light sources and associated optics.
		This requires the center of the entrance pupil of the eye to lie at the center of curvature of the hemisphere.
	webeye.ophth.uiowa.edu /ips/GEN-INFO/standards/IPS78.HTM (3601 words)

	External pupil lens system - US Patent 6563654 (Site not responding. Last check: )
		The pupil distance (from the entrance pupil to the first lens) of a typical external pupil lens system is limited to about 0.7 of the effective focal length (EFL).
		A conventional external pupil lens is therefore a very complex optical system, consisting of many lenses of complex design, some of which are made of special glass materials which are expensive and difficult to fabricate, and having an entrance pupil distance limited to about 1.5 times the EFL.
		The entrance pupil (also called the aperture stop, which determines the amount of light that traverses the optical system) is located external to the lens system, 7.5 inches in front of the first lens, which is more than three times the EFL.
	www.patentstorm.us /patents/6563654.html (2913 words)

	LABORATORIO DE OPTICA: JOSA95 (Site not responding. Last check: )
		One of the pupils was 1.5 mm in diameter, yielding a single pass image which was close to that of a diffraction limited system, and the other pupil was significantly larger.
		For the unequal entrance and exit pupil case, and in particular when one of the pupils is small enough to consider the eye as diffraction limited, the complete optical transfer function, including phase, can be computed by dividing the Fourier transform of the double pass image by the diffraction limited MTF.
		The 1.5-1.5 mm pupils retinal image is circularly symmetric and in consequence does not affect the shape of the double pass images obtained with unequal entrance and exit pupil sizes.
	iriso.fcu.um.es /publications/JOSA95/josa95.html (4171 words)

	Vignetting while Digiscoping
		It is the depth of the entrance pupil for the range of camera focal lengths that is the primary determinant of how easy it will be to get a good unvignetted zoom range in an afocal system.
		So it is no surprise that the location of the entrance pupil is seldom accurately known and is typically deduced by noting the eye relief needed to give the camera the full AFOV of the eyepiece.
		If the exit pupil of the eyepiece and entrance pupil of the camera lens are very close to coincident, then stopping down the camera lens (changing to a larger f-number or smaller aperture diameter) will not affect vignetting.
	www.jayandwanda.com /digiscope/vignette/vignetting.html (2313 words)

	OHP Preprint No. 126 (Site not responding. Last check: )
		It causes a densification of the exit pupil, in comparison with the entrance pupil: the size/spacing ratio of the sub-pupils is considerably increased.
		The displacement of the diffraction function sketched in figure 3 is negligible when the pupil is highly densified, in which case the image of an extended object is a convolution of the intensity distributions in the object and the interference function, followed by a multiplication with the diffraction function.
		Indeed, the densified pieces of the wavefront collected in the entrance pupil cannot be distinguished, in terms of diffraction, from the continuous wavefront in the exit pupil of a conventional telescope.
	www.obs-hp.fr /www/preprints/pp126/pp126.html (4225 words)

	Entrance Pupil Database - PanoTools.org Wiki
		Wouldn't it be great if everyone entered their values for their NPP / Nodal Point / Entrance Pupil for lens and camera combinations.
		Facing the side of the lens, the distance from the base of the lens to the Entrance Pupil.
		To calculate the Entrance pupil distance add the Tripod Mount Length (L1) from the camera and the Entrance Pupil Length (L2) from the lens.
	wiki.panotools.org /Entrance_Pupil_Database (555 words)

	The Role of the Pupil
		Pupil size is arguably the most important predictor of night vision disturbances, but obtaining an accurate measurement is sometimes difficult.
		When pupil size is measured, the observer sees a virtual image of the pupil formed by the cornea (33).
		In cases where the pupil dilates larger than the optical zone, the ratio of relative retinal irradiance between the image and the blur circle may be more important in determining who develops night vision disturbances (7).
	www.refractivesource.com /doctors/clinical_pearls/role_pupil.htm (2520 words)

	Journal of Vision - Ophthalmic lens effects in hartmann-shack measurements, by Campbell, Bueno, Hunter, & Kisilak
		The third effect of auxiliary lenses on aberrations is due to their magnification of the entrance pupil of the eye.
		If the pupil minification is not considered, these samples will be analyzed as if they originated from smaller pupil sizes and the amount of aberration intrinsic to the eye will be overestimated.
		Conversely, for the analysis of a fixed pupil size, the minification of the entrance pupil by the spectacle lens will increase the aberration of the spectacle/eye combination relative to the eye alone.
	www.journalofvision.org /3/12/29 (359 words)

	BirdForum - View Single Post - Fuji 6900 (Site not responding. Last check: )
		On my CP5000, the iris/shutter (which we are assuming is approximately where the entrance pupil is located) seems to move quite a bit forward during some portions of the lens' movement.
		What we are seeing is a good indication that the entrance pupil is very far back from the front lens element.
		The entrance pupil is very far away from the scope's exit pupil.
	www.birdforum.net /showpost.php?p=183118&postcount=16 (389 words)

	Machine Vision Guide - Lens Fundamentals (Site not responding. Last check: )
		Everything in front of the entrance pupil is said to be in object space.
		The entrance pupil is generally located within the physical lens, but not always.
		The exit pupil may be in front of or behind the entrance pupil.
	www.mellesgriot.com /products/machinevision/lef_4.htm (623 words)

	December 1999 Newsletter
		However, as you get older the entrance pupil is no longer able to open fully to 7mm, but rather only to about 5.5mm.
		When the exit pupil is 0.5mm or less, the bundle of light entering your eye may be obstructed by floaters, those little crappy junky dudes that are floating in your eyeball.
		I guess the third way is to have a doctor give you eyedrops and measure your pupils, but not being an astronomer, he/she may not be concerned enough to measure that as accurately as you want.
	astro.sci.uop.edu /~sas/Newsletter/TTN_Pupils.html (1045 words)

	OHP Preprint No. 125 (Site not responding. Last check: )
		the images obtained from each sub-aperture, with the exit pupil distorted in such a way that the sub-pupils are magnified with respect to their spacing, the pattern of their centers being conserved, as shown in the example of figure 1.
		This pupil densification shrinks the halo of diffracted light otherwise generated by Fizeau-type recombiners, thereby concentrating the energy in the central peak and neighbouring sidelobes.
		The former requires a compact pupil with little obscuration, which is in principle achievable with careful densification as sketched in figure 1.
	www.obs-hp.fr /www/preprints/pp125/pp125.html (3618 words)

	Adapter for optically coupling a photographic camera with a viewing device - Patent 4157216
		Located within the housing in the plane in which the first relay lens forms the aerial image is a diffuser structured for spreading the optical viewing device's exit pupil so that it substantially matches the size of the camera's entrance pupil.
		As is apparent, the entrance pupil 44 of the camera's viewing system occupies only a portion of the entrance pupil 42 of the camera's objective taking lens 16 and is also laterally offset with respect to the optical axis of the camera's taking lens 16.
		The field lens 74 is structured in a well known manner to form an image of the endoscope's exit pupil 55 as seen through the first relay lens 72 onto the entrance pupil 42 of the camera 12 as seen through the second relay lens 78.
	www.freepatentsonline.com /4157216.html (3005 words)

	BioMed Central \| Full text \| Variability of wavefront aberration measurements in small pupil sizes using a clinical ...
		Prior to the presentation of the results for the scaled pupils it is of interest to report on the variance of the raw wavefront aberration data (50 measurements) for the full-size pupil of each subject.
		This observation, in conjuction with the high accuracy of the refraction estimated objectively from wavefront aberration data when small (~3 mm) pupils are used[13,39,40], is of considerable importance, as this means that the COAS clinical aberrometer may be used as a reliable and accurate autorefractor.
		However, care must be taken when large pupils are tested, as the objective estimation of refractive error may lead to ambiguous results, due to the influence of higher-order aberrations on the determination of correction[40,41].
	www.biomedcentral.com /1471-2415/4/1 (4533 words)

	DOF Calculations for Telephotos
		The f-number is defined as the focal length divided by the diameter of the entrance pupil, not the aperture as such.
		The entrance pupil is the aperture as seen through the glass of the front lens cell, so if that cell has a high power the size of the entrance pupil can be fairly different from that of the hole formed by the aperture blades.
		is the diameter of the entrance pupil, the corresponding substitution
	www.largeformatphotography.info /lfforum/topic/499305.html (2036 words)

	Nodal Point - PanoTools
		Those communities have no special name for the no-parallax point, and their term "entrance pupil" properly refers to a region around the no-parallax point, rather than the point itself.
		(The entrance pupil is the image of the limiting aperture or diaphragm, as seen through the front of the lens.) Sigh...
		Some lenses, notably fisheyes, do not have a single no-parallax point because the location of the entrance pupil depends on the angle away from the lens axis.
	www.panotools.info /mediawiki/index.php?title=Nodal_Point (346 words)

	[No title]
		(4) The entrance pupil is located 12.5 mm to the right of the lens based on the results in (1).
		The diameter of the entrance pupil is 15 mm based on the result in (2).
		The entrance window coincides with the object plane and has size 4 cm.
	www.nova.edu /~bjiang/lectures_files/GO_problems_Ch_10.doc (435 words)

	Entrance Pupil Database - PanoTools
		This is easy to measure and is dependent only on the camera body The second table shows the actual entrance pupil distance which is only dependent on the lens itself.
		A negative value means the entrance pupil is before the lens base.
		To calculate the Entrance pupil distance add the Tripod Mount Length (L1) from the camera and the Entrance Pupil Length (L2) from the lens.
	www.panotools.info /mediawiki/index.php?title=EntrancePupildb (466 words)

	Journal of Refractive Surgery
		The parallax error associated with localizing corneal positions by tracking the subjacent entrance pupil center was quantified.
		Thus, if the eye tracker registers a lateral shift of the entrance pupil of 0.2 mm away from the tracking reference axis, the point of interest located on the cornea would essentially be 0.26 mm away from this reference axis.
		The fact that corneal displacement was generally underestimated by up to 30% of the measured entrance pupil shift demonstrates the severity of the parallax effect.
	www.journalofrefractivesurgery.com /showAbst.asp?thing=8585 (316 words)

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