Viewing and Lenses

2021 ◽  
pp. 47-75
Author(s):  
James E. Cutting
Keyword(s):  
Visual Fields ◽  
Image Artifacts ◽  
Wide Angle ◽  
Depth Of Focus ◽  
Screen Size ◽  
Aspect Ratios ◽  
Emotional Effects

How do displays—those of smartphones, tablets, laptops, televisions, and movie screens—fit with how people see? This chapter discusses acuity, visual fields, and how aspect ratios and screen size interact with them. It also considers lenses to photograph and project movie images, their lengths, their angles of view, and other effects such as their falloff in luminance and image artifacts that they create—bokeh and flare, depth of focus, and distortions of shape. Finally, it considers types of lenses—wide-angle, normal, and telephoto; spherical and anamorphic—and discusses how these are used by cinematographers to create emotional effects, the buildup of anxiety and the change of emotion, and how they can induce fearfulness.

Evaluation of Two Night–Vision Devices

1990 ◽  
Vol 84 (10) ◽  
pp. 539-541
Author(s):  
J. Robinson ◽  
S.M. Story ◽  
T. Kuyk
Keyword(s):  
High Intensity ◽  
Night Blindness ◽  
Visual Impairments ◽  
Visual Fields ◽  
Night Vision ◽  
Wide Angle ◽  
Blind Individuals ◽  
High Intensity Light

Night-blind individuals often have restricted visual fields or other visual impairments that limit their ability to travel at night. The study reported here compared two night-vision devices: one wide-angle light and one with a high-intensity beam. It concluded that no one night light is best for all individuals and that depending on the cause of the night blindness, a smaller angle, high-intensity light may be more useful than a wider angle one.

The eye of the humboldt penguin, Spheniscus humboldti : visual fields and schematic optics

1984 ◽  
Vol 223 (1231) ◽  
pp. 197-222 ◽  
Keyword(s):  
Pupil Size ◽  
Visual Fields ◽  
Depth Of Focus ◽  
Maximum Width ◽  
Image Brightness ◽  
Vertical Extent ◽  
Binocular Field ◽  
The Mean ◽  
Schematic Eye ◽  
Humboldt Penguin

Construction of a schematic eye indicates that the eye of Spheniscus humboldti is aquatic in design. The lens has a power of 100 dioptres (D) while (in air) the cornea has a power of 29 D. In air, the eye is myopic (approximately 28 D) but in water it is emmetropic. Minimum pupil size would seem insufficient to allow the pupil to function as a stenopaic aperture and increase depth of focus sufficiently to overcome the eye’s aerial myopia. Entry into water reduces maxim um image brightness by approximately three times. In air, the maximum width of the retinal binocular field is 45° and this occurs approximately 10° above the line of the bill. The bill intrudes into the retinal field and binocular field width in the plane containing the bill and the optic axes is 28°. The vertical extent of the binocular field is 125°. In the plane containing the optic axes the cyclopean field equals 282° and the optic axes diverge by 116°. In this plane the mean uniocular field is 155° with the temporal hemifield approximately 11° larger than the nasal hemifield. Entry into water reduces the widths of the visual fields such that maximum binocular field width is only 17° and the vertical extent is reduced to about 80°. Binocular vision is lost in the plane of the bill, and the uniocular retinal field is reduced by 32° and the cyclopean field by 36°.

A Study of the Effectiveness of the Wide Angle Mobility Light

1985 ◽  
Vol 79 (3) ◽  
pp. 109-111 ◽  
Author(s):  
Diane L. Morrisette ◽  
Gregory L. Goodrich ◽  
Michael F. Marmor
Keyword(s):  
Night Blindness ◽  
Visual Fields ◽  
Error Rates ◽  
Night Vision ◽  
Wide Angle

The Wide Angle Mobility Light (WAML) is a commercially available night vision aid. The present study tested the effectiveness of the device in helping night-blind subjects walk a course of residential streets at night. It was found that the WAML significantly reduced error rates ( p< .05). The results suggest that the WAML can be a useful device for most individuals who have night blindness with constricted peripheral visual fields.

CBED Shadow Images and Cs:Aberration Measurement

1982 ◽  
Vol 40 ◽  
pp. 696-697
Author(s):  
R. W. Carpenter ◽  
I.Y.T. Chan ◽  
J. M. Cowley
Keyword(s):  
Focal Point ◽  
Spherical Aberration ◽  
Optic Axis ◽  
Wide Angle ◽  
Caustic Surface ◽  
Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

Record Wear Studies by Scanning Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 364-365
Author(s):  
M.D. Coutts ◽  
E.R. Levin ◽  
J.G. Woodward
Keyword(s):  
Electron Microscopy ◽  
Constant Velocity ◽  
Peak Velocity ◽  
Great Depth ◽  
Depth Of Focus ◽  
Sweep Frequency ◽  
Transmission Electron ◽  
Test Record ◽  
Lateral Mode ◽  
Scanning Electron

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.

Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

Developmental Risk Through a Wide-Angle Lens

1987 ◽  
Vol 32 (1) ◽  
pp. 54-55
Author(s):  
Jack P. Shonkoff
Keyword(s):  
Wide Angle ◽  
Developmental Risk ◽  
Wide Angle Lens
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