camera usage photography i com 241. single lens reflex camera uses interchangeable lenses higher...
TRANSCRIPT
Camera Usage
Photography I
COM 241
Single lens reflex camera
• Uses interchangeable lenses
• Higher quality image than point and shoot cameras– Greater resolution
• DSLR– Digital single lens reflex
Exposure
• Shutter speed + aperture = exposure
• Basically correct exposure tells camera how much light to let in camera to produce the best possible image
• Shutter speed controlled in camera– Shutter opens and closes
• F-stop controlled by lens– Size of hole that light comes thru
• Both control how much light let into camera
Shutter• Amount of time the shutter is open
– Controls amount of light that enters camera
• Settings are in fractions of a second– So a shutter speed of 4 = 1/4 of a second– A shutter speed of 60 = 1/60 of a second
• Each shutter setting is half (or double) the next
• Typical shutter speeds– 1, 2, 4, 8, 15, 30, 60, 125, 250, 500– Little different on digital cameras
Slow shutter speed – 1/8 to 1/30 of a second
Fast shutter speed – 1/125 to1/500 of a second
Bike rider: slow shutter speed during the day (pan shot)
Car lights: slow shutter speed at night (time exposure)
Fast shutter speeds during the day
Camera motion• Faster shutter speed, less camera movement
• Longer the focal length of lens, more have to worry about camera movement
• General rule of thumb– Shutter speed greater than or equal to focal
length of lens*
Aperture
• Opening in the lens thru which light enters camera– Control this by making
opening larger or smaller
• Measured by f-stops– f/1.4, f/2, f/2.8, f/4,
f/5.6….f/64
The aperture, or hole in the center of the lens, gets smaller as f number or f-stop increases
• Each f-stop is half as fast as the previous one
• f/1.4 is largest and “fastest”– Admits the most light
• When go from f/2 to f2.8, that’s referred to as “stopping down”
Shutter closed Shutter open
Depth of field/aperture
• Area of focus is known as depth of field
• As decrease size of aperture, depth of field increases– More in photo (background and foreground) is
in focus
• Shallow depth of field, lower f-stop
• Greater depth of field, higher f-stop
• shot at f/2.8• focus is on boy in
middle
• aperture setting is f/16
• focus is on boy in middle
Determinates of depth of field
• Aperture– Smaller aperture, greater depth of field
• Lens– Shorter the lens, the greater depth of field
• Wide angle vs. telephoto
• Distance from subject– Greater distance from subject, greater depth of
field
Aperture / shutter speed
• Each smaller f-stop cuts amount of light in half
• Each increase in shutter speed cuts amount of light in half
• Maintain the same exposure by:– Increasing shutter speed, decreasing f-stop– Or vice versa
500 / f2250 / f2.8125 / f 460 / f5.630 / f8
15 / f118 / f16
Correct exposure
Open up f-stop, use faster shutter speed
Stop down f-stop, use slower shutter speed
• Difference is in motion and depth of field– Faster the shutter speed less blurring– Higher the f/stop (f/16) greater the depth of
field
• 1/4 sec, f/16
• Small aperture (f/16) produces great depth of field
• But bird’s wings are blurred
• 1/250 sec, f/2.8
• Freezes bird’s wings
• Background is now out of focus
ISO
• Sensitivity to light
• Higher ISO, more sensitive to light– Good for low light, fast action– Makes image look more coarse, grainy
• Low ISO gives better resolution
• 100, 200, 400, 800, 1600
• Can change on each shot– Digital camera
Determinates of exposure
• Shutter speed– Faster shutter speed, less light strikes film
– Stop action
• F-stop– Smaller aperture (f/16), less light strikes film
– Depth of field
• ISO• Sensitivity to light
– 800 ISO is more sensitive than 200 ISO
– Also looks a little grainer
Light meters
• Reflected– Meters light reflected from subject– Built into cameras
• Incident– Measures light falling on subject
What light meter “sees”• Averages all tones in a scene
• Converts them to 18 percent gray
High contrast scenes
• Light background– Causes subject to be underexposed
• Dark backgrounds– Causes subject to be overexposed
How to compensate
• Move in closer
• Meter the palm of your hand
• For landscapes tilt the camera down