Small glass wall cases {shadow box}| can display objects.
Holders {stereopticon} can have picture for left eye and picture for right eye, to better show depth [1838].
Horizontal platforms {sundial}| can have markings for daylight hours, and a middle rod or plate casts a shadow to indicate time.
In dim light, leaving lens open {time exposure}| can make photographs.
Copying machines {mimeograph}| can use blue dye pressed onto sheet, which then transfers to other sheets using solvent.
Light reflected from an image can make an electrostatic pattern on a plate, to which carbon particles cling and from which ink transfers to paper, to dry by heating {photocopier}| {xerox}.
Re-photographing a photograph through a glass screen that has 55 to 130 lines per square inch, vertically and horizontally {photoengraving}|, makes a negative that has very small dots.
process
Zinc or copper sheets {plate} with film emulsion receive negative. Light shines on plate to deposit silver. Developing plate and washing with acid dissolves zinc or copper at locations that have no silver. A roller applies ink to plate. Machines {printing press} press paper onto plate, to make heavy, medium, and light dots.
color
Color prints require yellow, red, blue, and black color plates {four-color process}. Art magazines use six plates and colors: yellow, red, blue, black, green, and white.
photographed document {photostat}|.
Photocopying {scanner, computer}| can transfer image to computer file.
Dry copying {xerography} can use electrically charged resin.
Transparent film slide is in front of oil lantern or light bulb {magic lantern}|. Light focuses on screen using lenses.
Projectors {movie projector}| can use holes in film sides {sprocket, movie film} to position new film frames behind lens, 16 or more times a second. Movie projectors hold film frames for 1/30 second. A rotating disc blocks light while film frames change. Film moves by gears pulling film through by film sprockets. Take-up reel turns as main reel turns.
Still cameras {camera}| can expose film to light to record images.
lens
Cameras can move lens forward or backward {focus, camera}, to make picture clear. Close-ups use lens far forward. Cameras can have bellows or extension rings to allow lens to go far forward. Special lenses {zoom lens} can keep focus at different magnifications. Special lenses {telescopic lens} can magnify. Special lenses {fish-eye lens} can be wide field.
diaphragm
Cameras can make smaller or larger openings {diaphragm, camera} {iris diaphragm} {f-stop}, so picture is not too dark or light. Diaphragms usually have an iris of overlapping metal leaves. Diaphragms have positions 2 for wide open, 2.8, 4, 5.6, 8, 11, 16, 22, and 32 for almost closed. Larger numbers reduce area by half.
shutter
Cameras can open for periods {shutter, camera}. Shutters are fast, so motions are not blurs. Shutters open long enough to receive enough light. Shutter irises can be set near lens {between-the-lens shutter}, which have speeds from 1/2000 second to several seconds. Shutters used in small cameras can be rectangles, which pass across opening near film at fixed speed but which have adjustable size.
Camera shutter speeds are usually 1/25, 1/50, 1/100, and 1/200 second. Times of 1/50 second or faster prevent unsteady-hand blur.
accessories
Camera accessories include three-legged stand {tripod}, colored plastic disc {filter, camera}, and electronic flash {flashgun}.
Cameras {movie camera}| can have a shutter that repeatedly opens for 1/30 second. Cameras use holes in film sides {sprocket, film} to position new film frame behind lens, 16 or more times a second. Cameras hold film frames for 1/30 second. Cameras repeat the process. Film moves by gears pulling film at film sprockets. Take-up reel turns as main reel turns.
Mirrors reflect image onto ground glass screen {reflex camera}|.
Film lines or spots {blip}| can be for timing or counting.
A hot smooth metal plate {ferrotype}| pressed against paper emulsion can make glossy paper, or dark enameled metal can create a direct positive image.
Emulsions {film}| can contain silver-compound molecules.
camera
Light enters camera lens and focuses on film. Black-and-white film has silver bromide or silver iodide crystal emulsion embedded in cellulose acetate. Light separates silver from silver bromide, to make latent image. People remove film from camera in the dark.
develop
Chemical treatment {developer, film treatment} makes actual image. Developer chemicals liberate more silver around silver already present, to bring out image. Chemical treatment {fixer, film treatment} {hypo} sets image permanently {negative film} in transparent reverse image. Fixer washes away remaining silver bromide, so film cannot change anymore if exposed to more light.
printing
Passing light through negative and lenses {enlarger, photography} can make a larger print {positive film}. Print paper has silver bromide crystals in gelatin {emulsion, film}. Print paper develops and fixes. Negative can be directly on top of print paper and have direct exposure to light {contact printing, film}.
transparency
Transparent negatives {slide, film} {transparency, film} can be for projection.
color
Color film has three layers, one for red, one for blue, and one for green. Layers have dyes to filter out other colors.
instant
Instant picture cameras {Polaroid camera} transfer negative to positive by pressing both together to release chemicals.
non-glossy surface {matte, surface}|.
Film can display all colors {panchromatic}|.
Telescopes and microscopes have a lens {magnifying lens}| that enlarges images.
Telescopes and microscopes have a light-gathering lens {objective lens}|.
Telescopes and microscopes have a lens {ocular}| near eye for magnifying.
Thin fused silica, glass, or plastic rods {optical fiber}| can transmit light. Outside layer {cladding} reflects rays. Absorbing high-angle rays and reflecting low-angle rays makes one axial light ray. Refocusing light by refractive-index gradient makes one axial light ray. Wavelengths amplify in region with rare-earth erbium ions added, which laser excites. Over 150 wavelengths can be in fibers using multiplexing {dense wavelength division multiplexing} (DWDM), which allows 400 gigabits per second.
Blocks {superlens}| {metamaterial} can have thin wires in parallel planes {split-ring resonators} (SRR) a short distance apart, which have negative electrical permittivity and negative magnetic permeability and so negative refractive index. Forces from arrays push back on photons. Negative refractive index makes receding object blue-shifted. Cerenkov radiation travels in opposite direction, not forward. Refraction at boundary from positive to negative refraction bends light more, so it bends past perpendicular.
two attached low-magnification adjustable telescopes {binoculars}.
Electron beams can pass through {transmission electron microscope}, or reflect from {scanning electron microscope}, 0.1-micron thin slices {electron microscope}| (EM). Electric and magnetic fields focus electrons onto a phosphorescent screen. Microscopes can use electrons with energy above 1 MeV, because they act like X-rays. Electrons can pass through tissue and focus. Electron microscope resolution is 10^-10 meter.
Concave and convex lenses can focus and magnify images that are small and far away {telescope}|. Light amount increases with larger opening. Refracting telescopes have a large lens that collects light to a focal point, and a second small high-curvature lens that focuses image for viewing. Reflecting telescopes have a large lens that collects light to a mirror, which focuses light on a second small high-curvature lens that focuses image for viewing.
X-ray beams can pass through 0.1-micron slices {x-ray microscope}|. X-rays focus by electric and magnetic fields onto phosphorescent electron-gun-TV-like screen.
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Date Modified: 2022.0225