Exam Flashcards
3 elements of exposure
Shutter speed, aperture, ISO
What is a stop?
The term for a camera change that doubles or halves the light
What is noise?
An image problem resulting from high ISO
What is 18% grey?
The tone that centre-weighted light meters average light to
What is reciprocity?
Multiple settings providing the same exposure value
What is my camera’s X-Sync speed?
1/250 of a second
What is a guide number?
A measurement of flash output
What is dragging the shutter?
A technique for using a slow shutter with flash
What is off-camera or oblique flash?
The flash method used to bring out surface detail
What is inverse square law?
The rule that describes how flash light falls off over distance
What is the rule of thumb for minimum shutter speeds for handheld photos?
The reciprocal of the focal length of the lens
What is exposure compensation?
The tool for adjusting exposure or flash to suit an individual scene
What is a normal 50 mm lens?
A lens that gives perspective similar to the human eye
What is evaluative metering?
Canon metering system that uses an algorithm to determine exposure
What is the aperture that gives the shallowest depth of field on your macro lens?
2.8
What is the preferred f-stop for taking photos of fingerprints with the 100 mm macro?
f/11
What is the hyperfocal distance?
The distance that you would focus to obtain maximum depth of field
What are the 3 factors that affect depth of field?
Distance, f-stop, and focal length
What are circles of confusion or blur circles?
A lens creates these geometric shapes in images that affect apparent sharpness
What is the type of file format that provides a “digital negative”?
RAW
What is a “working copy”?
Forensic image enhancement must only be applied to this copy of a file
What is JPEG?
The file format that continually compressed files every time it is resaved
What is TIFF?
The common file format considered “lossless” compression
JPEG is classed as what type of compression format?
Lossy
When should scale be included?
With any photo that may be used for comparison with a known source
What is “filling the frame”?
A strategy for maximizing use of the surface area of the image sensor in close-up photos
What lens to subject angle should be used to minimize distortion?
90 degrees, perpendicular to the subject
What does SWGIT stand for?
Scientific Working Group on Imaging Technology
What is SWGIT used for?
Forensic photographer follow the standards set by this group
What type of lens should be used whenever you are attempting to minimize distortion?
A “normal” lens
What is the f-stop that your flash must put out to achieve f11 at life size on your macro lens?
f22
What are the 3 elements of the exposure triangle?
Aperture (Av), shutter speed (Tv), ISO
What does Av mean?
Aperture
What does Tv mean?
Shutter speed
What does ISO refer to?
Sensor sensitivity
Depth of Field
Distance between nearest and furthest objects that are in focus in the camera
3 elements of depth of field
Aperture/f stop, lens distance to subject, focal length of lens
Aperture and depth of field
Large f stop (f2.8) gives shallow depth of field
Small f stop (f16) gives large depth of field
Distance and depth of field
Closer to subject gives shallower depth of field
Focal length and depth of field
Wider focal length has greater depth of field
Macro/Bellows 1:1
Requires 2 stops of additional light
Macro/Bellows 1:2
Requires 1 stop pf additional light
How to calculate guide number
GN = f stop x distance
X-sync speed
Fastest speed that allows flash units to synchronize with the shutter so that flash only fires when shutter is open
X-sync speed for our camera
1/250
