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FSC303 > L2-3: camera, photography, note taking > Flashcards

L2-3: camera, photography, note taking Flashcards

1
Q

how does a digital camera work [prob don’t need to know this for exam]

A

shutter opens and allows light to pass through the lens and strike a photosensitive material

  1. take picture, light passes into lens of camera
  2. image is focuses on CCD
  3. CCD generates an analog signal that represents the image
  4. the analog signal is converted to a digital signal by an ADC
  5. a processor in the camera adjusts the quality of the image and usually stores the digital image on a miniature mobile storage media inserted in the camera
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2
Q

2 sensors for digital cameras

A

CCD [charged couple device]
and
CMOS [complimentary metal oxide semiconductor]

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3
Q

explain the CCD sensor

A
  • horizontal and vertical row of charge capacitors
  • contains light sensitive pixels that measure the light energy striking each pixel
  • a colour filter [bayer filter] sits on top which allows certain pixels to only measure certain colours of light waves
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4
Q

bayer filter

A
  • colour filter in CCD sensor
  • RGB primary/additive colours
  • each pixel only reads one colour
  • weighs out the light to determine colour
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5
Q

explain the CMOS sensor

A
  • each pixel has its own ADC [analog to digital converter] attached, information gets converted immediately

ADC:
- as light hits the pixels, an electric charge is created and a measure in the change of voltage is recorded at each pixel sight
- the data collected in each pixel gets converted into a digital signal

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6
Q

what is SWGIT

A

scientific working group on imaging technology

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7
Q

what is the goal of SWGIT

A

to ensure the successful introduction of forensic images in a court of law

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8
Q

what are not acceptable means of introducing photographs in court [SWGIT]

A

cell phone images
special effects
filters

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9
Q

what is an accepted imaging practice in forensic science, law enforcement, and the courts [SWGIT recco]

A

digital imaging [section 1.4]

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10
Q

what are SWGIT equipment requirements for digital photography [SWGIT recco]

A

[section 2.1] image capture devices should be capable of rendering an accurate representation. different applications will dictate different standards of accuracy

equipment:
- DSLR camera
- interchangeable lenses
- off-camera flash
- remote shutter release
- tripod and tripod mount
- SD cards

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11
Q

interchangeable lenses

A

zoom lenses
- telephoto lenses

fixed lenses
- macro lenses
- wide angle lenses

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12
Q

zoom lens and use

A
  • 24-70mm, 18-55mm
  • variable focal lengths

use
- incorporates wide angle to telephoto in one lens - able to change focal lengths on the fly
- overall, midrange photos

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13
Q

fixed lenses [prime lens] and use

A
  • macro lens [60mm, 105mm]
  • wide angle lens [20mm]

macro lens use:
- take extremely close photographs, making smaller objects appear bigger
- close ups

wide angle lens use:
- wider angle of view
- effect of moving subject away from camera
- wider field of view
- landscapes, cityscapes, architecture

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14
Q

types of digital file types

A

JPEG - joint photographic experts group
TIFF - tagged information file format
RAW - unprocessed data, contains all of the image info captured from the camera’s lens

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15
Q

what file format does STPS use and why

A

JPEG - for court purposes
RAW - for analysis/comparison purposes

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16
Q

FRONT camera parts and functionality [L2:37]

A
  • sub command dial: adjusting aperture
  • mode dial: change the mode of camera [manual, auto, aperture, etc.]
  • activate in-camera flash button
  • lens release button
  • auto focus mode: switching between manual and autofocus
  • lens: to focus light from what is being photographed, and allow it to pass through the lens to further generate a photograph
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17
Q

LENS parts and functionality [L2:38]

A
  • mounting index dots: to help mount and remove lens [match up dots from lens to camera]
  • lens-release button: to release lens
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18
Q

TOP camera parts and functionality [L2:39]

A
  • accessory shoe: for optional flash unit
  • power switch: on/off
  • record button
  • shutter release: to take picture
  • mode dial: change camera mode
  • release mode dial: changing release mode [what happens when shutter is released]
  • metering mode: changing metering mode [camera’s way of measuring light of the scene]
  • exposure compensation button: used with command dial to manually increase/decrease exposure
  • diopter: controls lens system in viewfinder, can adjust to match focus of viewfinder to you eye
  • control panel screen: displays settings - aperture, shutter speed, etc.
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19
Q

REAR camera parts and functionality [L2:40]

A
  • playback button
  • delete button
  • menu button
  • menu icon strip
  • multi selector/ OK button
  • focus selector lock switch
  • main command dial: adjusting shutter speed
  • live view switch
  • speaker
  • memory card access light
  • rear IR receiver
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20
Q

LENS anatomy [L2:41]

A
  • filter thread [filter size]
  • front lens element
  • lens hood mount
  • zoom ring
  • selected focal length
  • distance scale and focusing range
  • lens information
  • focus ring
  • alignment dot
  • rear lens element/mount
  • serial number
  • vibration reduction controls
  • manual/auto focus switch
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21
Q

describe focal length

A
  • the distance between the lens and image sensor when the subject is in sharp focus
  • units = mm
  • lenses measured in focal lengths
  • not a measurement of the actual length of the lens – but the optical distance at which light rays converge to form a sharp image in the sensor
  • field of view = how much you can get in the picture
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22
Q

what is field of view

A

how much you can get in the picture

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23
Q

short or long focal length for wide field of view

A

short focal length

shorter focal length –> wider field of view, lower magnification [wide angle lens]

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24
Q

short or long focal length for narrow field of view

A

long focal length

longer focal length –> narrower field of view, higher magnification [close up image]

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25
Q

describe exposure

A

proper exposure means recording a full scale of tones, from detail in the dark areas [shadows] through to the brightest parts of the image [highlights]

exposure = intensity x time
- intensity/aperture
- time/shutter

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26
Q

what can exposure be controlled through

A

aperture and shutter speed

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27
Q

what is a histogram

A

graphical representation of the pixels exposed in your image

can indicate you need to adjust your exposure

28
Q

what does the left side of a histogram represent

A

blacks/shadows

29
Q

what does the right side of a histogram represent

A

whites/highlights

30
Q

what does the middle section of a histogram represent

A

mid-tones/greys

31
Q

what do higher bars on the left side of a histogram indicate regarding exposure of an image

A

image is under exposed

32
Q

what do higher bars on the right side of a histogram indicate regarding exposure of an image

A

image is over exposed

33
Q

describe ISO

A

each pixel in digital photography has a fixed sensitivity to light and is measured in ISO [international standards organization]

amplifying the signal increases sensitivity

34
Q

what happens when ISO is increased

A

sensitivity is increased –> background noise increases –> results in grainy look

35
Q

ISO scale

A

25, 50, 100, 400, 800, 1600, 3200, etc. [doubling sequence]

36
Q

what ISO level would produce a noisy image – 200 or 3200

A

3200

37
Q

describe diopter

A

a dial near the viewfinder

controls lens system in viewfinder, can adjust to match focus of viewfinder to you eye

38
Q

describe aperture

A
  • aperture = lens diaphragm
  • size of the opening in the lens
  • regulates the amount of light that passes through the lens and onto the sensor
  • similar to the function of our pupils in our eyes
39
Q

what are f-stops

A

aperture control is expressed in f-stops

f-stops are a universal system relating the focal length of the lens to the diameter of the entrance pupil

40
Q

are f-stops different for different lenses

A

no, regardless of the lens, the same amount of light is passed through at each f-stop

41
Q

what does a lower f-number mean

A
  • larger aperture
  • allow more light to enter the camera
  • shallow depth of field [ex. in 3 battery image, front battery is in focus]
  • blurry background
42
Q

what does a higher f-number mean

A
  • smaller aperture
  • allow less light to enter the camera
  • deep/greater depth of field [ex. in 3 battery image, all in focus]
  • not blurry background
43
Q

describe depth of field [DOF]

A

distance between the nearest and farthest objects which can all be brought into acceptable focus

44
Q

what is considered to be an acceptable DOF

A

1/3 in front of the subject, and 2/3 behind the subject

45
Q

when does the greatest DOF occur

A
  1. f-number is high
  2. lens focal length is short
  3. subject is distant
46
Q

describe shutter speed

A

shutter is a device that controls the length of time light is allowed to travel to the image sensor

47
Q

how is shutter speed expressed

A

as fractions of a second [ex. 1/60] or several seconds in length [ex. 5’’]

48
Q

what does a longer shutter speed mean

A
  • longer time
  • slower shutter speed
  • more light
49
Q

what does a shorter shutter speed mean

A
  • shorter time
  • faster shutter speed
  • less light
50
Q

what are 2 reasons slower shutter speeds from [B to 1/30] are used

A
  1. when there is no movement and more light is required to properly expose the image [low light or night photography
  2. when there is movement in the image and the photographer wants to portray the movement by blurring the subject [capture movement intentionally]
51
Q

what is B in shutter speed

A

stands for bulb

this setting will hold the camera shutter open until the shutter trigger is released

52
Q

what is the minimum shutter speed for handheld use

A

1/60

53
Q

at what shutter speeds must a tripod be used to produce clear images

A

shutter speeds slower than 1/60

54
Q

rule of reciprocity – how do aperture and shutter speed work together to achieve proper exposure if an image

A
  • if you increase time [slower shutter speed], then you must reduce the amount of light [smaller aperture]
  • if you reduce the time [faster shutter speed], then you must allow more light [larger aperture]
55
Q

what is BIT depth

A

number of tones between pure black and pure white

56
Q

purposes of forensic photography

A
  • first step in recording/examining a scene
  • accurate representation of the scene and physical evidence within the scene when you arrived
  • preserves the scene as is for future viewing
  • provide a permanent record for the courts
  • provides an inventory of evidentiary items
  • images are entered as evidence in court
  • meant to tell a story as you move through the scene
57
Q

order of photos at a crime scene

A
  1. ID card – allow investigators to be able to tell who took the proceeding photos
  2. scene establishing – leading up to scene, building/ apartment/ unit number, overalls of scene [4 corners]
  3. evidence establishing – items of interest that will be swabbed or collected for further analysis photographed in-situ with identifier marker [overall and midrange]
  4. closeups – of items of interest
58
Q

how to take closeups of items of interest

A
  • items can be moved
  • placed on a non-distracting background and laid flat
  • closeup should fill frame and include scale
59
Q

considerations of forensic photography

A
  • perspective – keep the back of the camera parallel to the subject to avoid distorted perspective
  • photograph at eye-level as much as possible
  • always use flash, even for indoor scenes
  • check DOF, especially on curved objects
  • AF mode requires contrast in order for it to function properly
60
Q

importance of who takes notes

A
  • who made or influenced the notes?
  • where did the info come from?
  • independent recollection of events or the scene - do not collaborate
  • discuss only factual details
61
Q

importance of when notes are made

A

notes are made during the event or shortly thereafter in order to allow you to record most of your observations

62
Q

importance of why notes are made

A
  • memory to testify in court
  • notes are scanned and available for everyone to see
  • lets supervisors or case managers know what you did
63
Q

rules of note taking

A
  • date is underlined
  • use 24 hour time
  • don’t leave empty lines/spaces
  • list times for arriving on scene starting photos, scene completion
  • always use ink [preferably black]
  • if you make a mistake, cross it out with a single line through, initial, and make correction
64
Q

proper format of note taking [steps]

A
  1. date [yy/mm/dd]
  2. RFD - report for duty [list time]
  3. RFD location
  4. weather
  5. CD - commence duty [list time]
  6. S/D - station details, briefing, who briefed you? what info
  7. offence and general occurrence number
  8. O/S - on scene, who is on scene with you? what are their duties?
  9. scene and item descriptions [number items]
  10. list time scene examination complete
  11. sign off once finished, ROD [report off duty] and sign name
65
Q

crime scene photography settings for ID, scene establishing, overall, and midrange photos

A
  • aperture or manual mode
  • focal length = 50mm
  • ISO = 200-400
  • aperture = f8
  • metering = matrix
  • lense = variable
66
Q

crime scene photography settings for close up photos

A
  • aperture or manual mode
  • focal length = 70mm to 120mm
  • ISO = 200-400
  • aperture = f8
  • metering = matrix
  • lense = variable
67
Q

crime scene photography settings for macro photos

A
  • aperture or manual mode
  • focal length = 60mm
  • ISO = 100
  • aperture = f16 or smaller (i.e. f22)
  • metering = matrix
  • lense = macro

FSC303 (9 decks)

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