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