Elements of Photographic Systems Flashcards
The simplest camera
Old cameras with just a pinhole for light and light sensitive material at the back wall
The simple lens camera
Old cameras with a simple lens (one simple element)
An adjustable Diaphragm
Adjustable Shutter
Diaphragm/Aperture stop
limits the amount of light reaching the film/sensor
Controls diameter (d) of the lens opening
Shutter
limits the TIME light is allowed to reach film/sensor
controls duration of exposure (t)
Exposure
The amount of energy (E) exposed onto sensor per unit sensor area
Focal length
the distance from the lens at which parallel light rays are focused to a single point
Fixed/constant in most cameras
f-stops
a measure of aperture
ex: f/1.4 or f/32
Larger f/n = smaller aperature
Which has a larger aperture/ larger opening:
f/1.4 or f/11
f/1.4 has a larger opening, letting in more light
Which has a smaller aperture/larger opening:
f/4 or f/8
f/4 has a larger opening, letting in more light
Aperture impact on brightness
Aperture has a direct impact on brightness
smaller f-stop means bigger opening and thus more light
Aperture impact on DoF
Smaller f-stop (f/1.4) will make foreground objects sharper, background blurry
Larger f-stops (f/32) bring both fore and background objects into focus
Depth-of-Field
The range of distance of the image that appears acceptably sharp
Impacted by aperture size
Shutter speed definition
How much light comes into the camera, measured in seconds.
More seconds lets in more light
Shutter speed impact on motion
faster shutter speeds (1/1000th sec) can freeze motion
Slower shutter speeds (1/2 sec) can cause motion blur
ISO definiton
Cameras sensitivity to light
Last setting to change
ISO impact on light/brightness
Higher ISO more light
Lower ISO less light
Higher ISO is subject to more noise due to more reflections
Why underexpose aerial photos
easier to fix in editing software
If overexposed then there are saturated pixels and you cant fix that
DSLR camera
Digital Single Lens Reflex
Digital sensor
Single lens
Reflex is mirror system for viewing
Reflex in DSLR
A system where a mirror splits the direct incoming light towards the optical viewfinder
Lets you see the exact view the sensor will and then flips shut when actually taking the image
Single-Lens filtering
Uses one blocking filter to capture 3 different wavelengths
These are vary wide bands subject to contamination from neighboring data
Fine for mapping, not great for remote sensing
Multi-Lens filtering
each lens has a devoted filter
Narrower bands
Better separation and identification of features
