Physics 3

Front 1

chromatic abberation

Back 1

dispersion causes different color lights to refract differently

needs to choose whether blue or red is focused

Front 2

achromatic doublet

Back 2

made of 2 different types of glass

converging glass converges more blue than red

diverging glass diverges more

Front 3

spherical abberation

and

how to correct

Back 3

when the top and bottom of the lens converges more than middle, creates circle of confusion

solved by putting in a stop, creating aperture (too small, no light)

Front 4

F-stop

Back 4

changes aperture

Front 5

stopping down

Back 5

makes aperture shrink

Front 6

concave lenses are ____ lenses

Back 6

diverging

Front 7

convex lenses are _____ lenses

Back 7

converging

Front 8

large aperture =

small aperture =

Back 8

lots of light and distortion

less light, less distortion

Front 9

depth of field

Back 9

distance object can change position by and still be in focus

Front 10

problems with viewfinders

Back 10

viewfinder image and real image are slightly different

composition will be different

cant tell if you are in focus

Front 11

parallax problem

Back 11

misalignment of what you see in viewfinder and what lens picks up

heads can be cut off

Front 12

ground glass

Back 12

transparent and rough surface, allowing to see image on other side

slow because glass must be removd after photo is set and photo film must be inserted in dark

Front 13

reflex camera

Back 13

light goes in , hits mirror and bounces up to viewfinder

mirror then moves, allowing light to hit film

distance from mirror-ground glass matches mirror-film so in focus in both places

Front 14

parts of reflex camera

why is prism needed?

Back 14

lens --> mirror --> prism --> eye

prism flips image right way up and inverses lateral inversion caused by mirror

Front 15

Biprism

Back 15

2 prisms - when image is in focus it is forming in middle of two prisms.

unfocused --> biprism splits

mounted in center of ground glass screen

Front 16

Auto focus

Back 16

sends out pulse of infrared , hits object then bounces back to camera

sensor chip measures time wave took to get back, calculates distance

Front 17

Regular cameras underwater?

Back 17

Autofocus doesnt work because sensor calculated for wave speed in air

Components calibrated for air, image in air and water form at different distances

Front 18

Magnification =

Back 18

image size seen through camera / image size viewed directly

= f (lens) / f (eye)

Front 19

standard lens

Back 19

50mm since f (eye) = 50mm

no difference between size in photo and actual size

Front 20

telephoto lens

Back 20

makes image bigger, used for far off objects

f>50mm

bigger f value --> bigger image

Front 21

lenses and distortions

Back 21

wide angle/fish eye causes barrel distortion

telephoto causes pincushion distortion

Front 22

macro lens

Back 22

uses telephoto lens to enlarge scene

difference between normal telephoto lens -- no distortions

Front 23

shutter

Back 23

speed window moves same always, width of window moving across film changes

quick exposure = narrow window
slow exposure = wide window

normal = 1/60 of a second

longer shutter is open --> more blur on moving objects

Front 24

Problems with fast exposures

and Solutions

Back 24

little light on film

solution: bigger lenses increase stop aperture, increasing light

Front 25

stop apertures and f numbers

Back 25

stop aperture given by "f number"

f number = focal length of lens/diameter of stops hole

f number indicates amount of light per unit area falling on film

large f --> dim

Front 26

Series of steps in photography

Back 26

Fast Object

fast shutter to reduce blur

less light

open stop (small f)

1. more distortion
2. small depth of field

Front 27

depth of field depends on...

Back 27

focal length of lens
object distance
stop size

Front 28

problem with fixed focus cameras

Back 28

very small aperture, very little light

Front 29

camera vs. eye

Back 29

compound lens = cornea and lens
stop = iris
aperture = pupil
film = retina

Front 30

eye diagram on pg 383

Back 30

know iris, pupil, cornea, lens, retina, vitreous and aqueous humor, fovea

Front 31

inverting spectacles

Back 31

proves that brain flips things right way up for us to see

Front 32

focusing in the eye

Back 32

most converging occurs at cornea surface

eye lens fine tunes the convergence so that the image is focused at retina

Front 33

accomodation

Back 33

muscle contraction produces change in lens curvature

how we ensure things stay in focus

Front 34

eye defects

Back 34

myopia - cornea converges too much

and

hyperopia - doenst converge enough

Front 35

myopia

advantage?

Back 35

too much convergence, problems focusing at infinity

focus in middle of eye

corrected using diverging lens or surgery

near point closer than normal

Front 36

hyperopia

Back 36

too little convergence, problems focusing close

focus behind eye

corrected using converging lens

Front 37

improvements to reduce spherical abberations

Back 37

graded index lens

aspheric lenses

Front 38

chromatic abberations in eye reduced by

Back 38

lens material has low dispersion

short wavelengths absorbed by lens

brain removes it

Front 39

plexiform layer

Back 39

nerves connecting to brain

recieves light converts to electricity for brain

Front 40

two types of detectors in eye

Back 40

rods and cones

Front 41

cones

Back 41

sensitive to color (wavelength) , produce a sharp image . need more light to function

Front 42

rods

Back 42

require low level of light

less refined

Front 43

fovea

Back 43

no rods, all cones centered there

directly behind lens, recieves images from center of scene being viewed

Front 44

how many cones in human eye?

how many rods?

Back 44

6 million , most located in fovea

120 million rods spread across retina

Front 45

adaptation

Back 45

response of rods and cones to changing light conditions

Front 46

photopic

and

scotopic

Back 46

photopic = cone dominated

scotopic = rod dominated

Front 47

lateral inhibition

Back 47

makes contrast more apparent

form of retinal processing

Front 48

what determines the color of an object?

Back 48

if the light waves are on or off resonance for the object

ex: for leaf, green is off resonance and thus not absorbed so leaf appears green

Front 49

when you shine light on a white object,

when you shine light on a black object,

Back 49

all colors are reflected so it appears white

all colors are absorbed, appears black

Front 50

3 parameters to describe complex colors

Back 50

hue

saturation

lightness

Front 51

hue

Back 51

spectral color that dominant wavelength corresponds to

nearest spectral color to the peak reflection

Front 52

saturation

Back 52

purity of a color

concentrated and steep wavelength graph, broader and more spread out (desaturated)

Front 53

most desaturated color?

Back 53

white

desaturated creates grayscale -- added colors , less concentrated

Front 54

lightness

Back 54

more light reflected = lighter

darker colors reflect less light

add black to make darker

Front 55

primary colors

secondary colors

Back 55

red green blue

cyan magenta yellow

Front 56

color mixing:

blue + green =

red + green =

blue + red =

blue + green + red =

Back 56

cyan

yellow

magenta (non=spectral color)

white

Front 57

why is magenta not a color?

Back 57

does not have a hue

Front 58

complimentary colors

example?

Back 58

two colors acting as one

blue + red + green = white
but
red + green = yellow

so blue + yellow = white and they are complimentary

Front 59

additive color mixing

Back 59

when different color lights overlap

color determined by adding distribution curves

ex: stage lights, pointillist painting

Front 60

subtractive color mixing

Back 60

when different colors are removed

ex: filters

Front 61

Filters

Back 61

Removes a color of light

example: complimentary colors yellow and blue

yellow + blue = white
so
blue - white = yellow

Yellow filter removes blue light!

Front 62

Subtractive process

Back 62

cyan - yellow = green
cyan - magenta = blue
magenta - yellow = red
cyan - yellow - magenta = black

Front 63

interference

Back 63

constructive --> bright
destructive --> dark