CS Photography Exam 2

differences in exposure are referred to as?

stops

4 variables affecting light exposure:

shutter speed, aperture, ISO, lighting

what is ISO?

the sensitivity of the camera’s sensor to light

Sensors that require more light for a proper exposure have ____ numbers

lower

Sensors very sensitive to light, therefore requiring less light for proper exposure, have _____ numbers

higher

how do you change ISO?

by pushing the button marked “ISO” and then rotating the rear command dial

what is the rule of thumb for CSP (relating to ISO)?

Use 400 unless it is a bright sunny day or taking exam quality photos, then use 100

what are the benefits of a lower ISO?

finer detail, less noise, enlarges well (but requires more light)

in manual mode, what order should you change variables in?

ISO, shutter speed, light meter, aperture

Shutter speed can be adjusted to control time (amount of time the shutter remains open) and three types of motion, what are they?

Photographer body movements

Motion of the subject being photographed

Movement of the camera

how are shutter speeds indicated?

fractions of a second

A ____ shutter speed can actually be beneficial to remove the distraction of snow or rain (this freezes the droplets)

slow

To eliminate possible blur from hand-holding the camera, use the shutter speed that is the closest to the ____ length of the lens inverted into a _____

focal, fraction

what 3 motions affect photo clarity?

photographer body movement, subject motion, camera movement

how do you change shutter speed?

rotate the rear command dial

what is the exposure triangle?

aperture, shutter speed, ISO

what is a light meter?

on the right side of viewfinder, it indicates a perfect exposure ( + = overexposure, - = underexposure)

In non-normal scenes, the light meter suggestion may not provide a proper exposure. Non-normal scenes may include:

• very light-colored scenes

• very dark-colored scenes

• Scenes with a lot of sky in the field of view

• Backlit scenes or scenes with both bright highlights and dark shadows in the same composition

what is aperture?

Size of the Opening In the Lens

what is f-stop?

a fraction relating the size of the aperture opening to the lens focal length

what does aperture do?

Controls depth of field (the area of the photo in focus)

The smaller the aperture opening, the ____ the depth of field

larger

for f-stops: ____ opening = larger f number

smaller

how do you change f-stop?

rotate front command dial

how is ISO represented?

in 100s

what is shutter speed?

Shutter speed controls the amount of time the shutter curtains remain open allowing light to strike the sensor

what is the most common shutter speed for CSI?

1/60th

The ____ the aperture opening, the larger the f-stop, the ____ the depth of field.

smaller, greater

what is the most common aperture for CSI?

F11 or above

For crime scene photography, the preferred Focus Mode is:

auto focus- area (AF-A) and single point AF

how do you view metadata?

go to the menu

what should you do with focus brackets?

align the primary subject with them to focus

in program mode, what does the camera select?

aperture and shutter speed

what is bracketing?

The intentional overexposure and underexposure of succeeding photos, taken from the same position, to ensure at least one of the images is properly exposed.

what does the camera select in the shutter priority (S or Tv) mode?

aperture and ISO

what does the camera select in aperture priority (A) mode?

shutter speed and ISO

what is NIST and OSAC

The National Institute of Standards and Technology (NIST) oversees The Organization of Scientific Area Committees for Forensic Science (OSAC) who provides guidelines and best practices for the discipline.

____ provides guidelines on examination quality photographs which are used for comparison purposes or to calculate precise measurements

OSAC

____ ____ are recommended bc they are self-documenting

labeled scales

what is the most common digital camera format?

JPG

what are some benefits of JPG files?

Requires less space

Images processed inside camera; they do not have to be converted to be viewed or opened.

Faster processing and downloading.

Compatible with most email systems

DO NOT use ___ format to save original images that you expect to enhance later.

JPG

what are some drawbacks of JPG files?

Lower dynamic range (color capture).

Images are compressed when opened, changed, re-saved; actual sensor data is discarded EACH TIME (degrades)

what is a RAW file? is it easily shared?

unprocessed sensor data; no

what is a TIF file? is it easily shared?

The most accurate and reliable method for storing processed images captured as JPG or RAW (most reliable); not easily shared

what is resolution?

The ability of the camera system to distinguish groups of alternating line pairs

what is SWGIT?

Scientific Working Group on Digital Technology: Determined the minimum resolution to be recommended for “examination quality” digital photographs was: 8 megapixels

what is acutance?

The camera’s ability to render a sharp edge of the subject as a sharp edge in the photograph. (crisp edges)

what is sharpness?

Overall the image is in focus, meaning the light coming into the camera through the lens converges at the sensor at exactly the right point.

what does a micro/macro lens do?

Magnifies small objects to fill the frame of a photograph

what is recommended for micro photography?

a ring light

what modes are best when using a micro lens?

aperture priority and manual

what is an issue with auto focus?

s it generally focuses the camera on the object in the center of the viewfinder

what should you do to improve DOF?

select a smaller aperture setting, then adjust other variables (shutter speed and ISO) to ensure correct exposure.

what is the rule of thirds?

As a general rule, DOF extends one third in front of the point of exact focus and two thirds behind the point of exact focus; therefore, focus one third of the way into the scene to maximize DOF

what is rule of half (better for CSI)?

To maximize DOF in scenes from 5’-30’, focus at a distance that appears midway between the top and bottom of the composed scene. Bracket your photos for best DOF

where should scales be placed?

on the same plane as the evidence to maintain accurate proportions