The Basic Functions of The Basic Functions of aa

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Exposure BasicsExposure Basics

The basic function of a 35 mm The basic function of a 35 mm Camera is to make a photographic Camera is to make a photographic Image.Image.

To make a good photograph you To make a good photograph you need the correct exposure.need the correct exposure.

To get the correct exposure you need to To get the correct exposure you need to expose the film or sensor to the right expose the film or sensor to the right

amount of light.amount of light.

There are 4 things that There are 4 things that control exposure.control exposure.

The LightThe Light The ISOThe ISO

Film/Sensor Film/Sensor

Sensitivity to LightSensitivity to Light

The ApertureThe Aperture

Expressed as f-stopsExpressed as f-stops

The ShutterThe Shutter

Expressed as fractionsExpressed as fractions

Light Affects Exposure.Light Affects Exposure.The amount of light available determines the The amount of light available determines the

ISO setting, ISO setting, the aperture setting and the shutter speed.the aperture setting and the shutter speed.

CloudyOvercast

Sunny night

The ISO number indicates how The ISO number indicates how sensitive the sensitive the

film or sensor is to light.film or sensor is to light.

The higher the number the more light The higher the number the more light sensitive.sensitive.

50 100 200 400 800 160050 100 200 400 800 1600

Less SensitiveLess Sensitive More More SensitiveSensitive

The aperture controls how much The aperture controls how much light passes through the lens to light passes through the lens to

the film or sensorthe film or sensor

○○ ○ ○ ○○ ○○ ○○ ○○ ○○

○ ○ ○○32 22 16 11 8 5.6 4 32 22 16 11 8 5.6 4

2.8 1.4 2.8 1.4Small Aperture opening Less Light

Large Aperture Opening

More light

The bigger the hole the smaller the number

Aperture numbers are fractions

The shutter opens and The shutter opens and closes and controls how closes and controls how

long the film long the film is exposed to light.is exposed to light.

2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/10001/500 1/1000

More time More light

Less time Less light

Shutter speeds are expressed in seconds and fractions of a second.

A Good exposure is a A Good exposure is a combination of ….combination of ….

1. Just the right amount of light 2. The Correct ISO 1. Just the right amount of light 2. The Correct ISO SettingSetting

3. The Correct Shutter Speed Setting 4. The Correct 3. The Correct Shutter Speed Setting 4. The Correct Aperture SettingAperture Setting

Bad ExposureBad Exposure Over ExposedOver Exposed

Too much lightToo much light

Under ExposedUnder Exposed Not enough lightNot enough light

The Bucket AnalogyThe Bucket Analogy

The goal is to open the faucet (aperture) for the The goal is to open the faucet (aperture) for the right amount of time (shutter) to fill the bucket right amount of time (shutter) to fill the bucket (film) with the right amount of water (light).(film) with the right amount of water (light).

A good exposure A good exposure is not all there is is not all there is to making a good to making a good

photograph.photograph.

The aperture controlsThe aperture controlsexposure AND depth of field…exposure AND depth of field…

○○ ○ ○ ○○ ○○ ○○ ○○ ○○

○ ○ ○○32 22 16 11 8 5.6 4 32 22 16 11 8 5.6 4

2.8 1.4 2.8 1.4Small Aperture opening Less Light Deep Depth of Field More in Focus

Large Aperture Opening

More light

Shallow Depth of Field Less in Focus The bigger the hole the smaller the

number Think Fractions

Shallow depth of Shallow depth of fieldfield

Deep depth of fieldDeep depth of field

Less in focus from near to far More in focus from near to far

The shutter controls exposure AND The shutter controls exposure AND motion…motion…

2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/10001/500 1/1000

More time More light Shows Motion

Less time Less light

Freezes Motion

Fast shutter speedFast shutter speed Slow shutter speedSlow shutter speed

Frozen motion Shows motion

The shutter speed and the The shutter speed and the aperture have a reciprocal aperture have a reciprocal

relationrelation If one goes up the other has to go If one goes up the other has to go

down to get an equivalent exposure. down to get an equivalent exposure. If you change the aperture you have If you change the aperture you have

to change the shutter speed.to change the shutter speed.

○○ ○ ○ ○○ ○○ ○○ ○ ○

○○○○○○32 22 16 11 8 5.6 4 32 22 16 11 8 5.6 4

2.8 1.4 2.8 1.4

2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 2’ 1’ 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 1/1000

Aperture Setting

More light

Less light

Shutter Speed Setting

Less light

More light

If you open the aperture you have to speed up the shutter, if you close the aperture, you have to slow down the shutter.

Lets say your f stop is set at f22 and your shutter Lets say your f stop is set at f22 and your shutter speed is set at 1/60. You are making a portrait of speed is set at 1/60. You are making a portrait of your grandmother and you want a shallow depth your grandmother and you want a shallow depth of field to eliminate a distracting background. of field to eliminate a distracting background.

If you change your aperture to f5.6, what is the If you change your aperture to f5.6, what is the correct shutter speed setting that will give you correct shutter speed setting that will give you an equivalent exposure?an equivalent exposure?

2’, 1’, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000,

1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32,

Apertures

Shutter speeds

The correct equivalent exposure is f/5.6 The correct equivalent exposure is f/5.6 @ 1/1000@ 1/1000

You have to change your shutter speed You have to change your shutter speed the same number of “stops” as you the same number of “stops” as you change your aperture, to get the change your aperture, to get the equivalent exposure.equivalent exposure.

In this case the aperture has moved 4 f-In this case the aperture has moved 4 f-stops (apertures) to let in more light, stops (apertures) to let in more light, so the shutter has to move 4 stops to so the shutter has to move 4 stops to let in less light.let in less light.

What shutter speed would you use if What shutter speed would you use if you want to show movement?you want to show movement?

1/301/30thth or slower or slower But…But… Be sure to use a tripod…Be sure to use a tripod… Or….you will get camera shake.Or….you will get camera shake.

Hand-holding the camera when using a Hand-holding the camera when using a shutter speed slower than 1/60 will shutter speed slower than 1/60 will cause the photograph to be out of focus. cause the photograph to be out of focus.

You are photographing a beautiful flower You are photographing a beautiful flower and your aperture is set at f/8 and your and your aperture is set at f/8 and your shutter speed is at 1/15shutter speed is at 1/15th. th. You forgot your You forgot your tripod so you need a faster shutter speed.tripod so you need a faster shutter speed.

What should you change??What should you change??

Aperture SettingsAperture Settings1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32,1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32,

Shutter Speed SettingsShutter Speed Settings2’, 1’, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 2’, 1’, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250,

1/500, 1/10001/500, 1/1000

You must change both the aperture and You must change both the aperture and the shutter…the shutter…

You need to speed up the shutter to You need to speed up the shutter to prevent camera shakeprevent camera shake

So you will need to change the aperture So you will need to change the aperture too, for an equivalent exposure.too, for an equivalent exposure.

A good exposure could be A good exposure could be F/4 @ 1/60F/4 @ 1/60thth

F/2.8 @ 1/125F/2.8 @ 1/125thth F/2 @ 1/250F/2 @ 1/250thth

Next you are shooting a landscape and you have a Next you are shooting a landscape and you have a meter reading that tells you to use f/5.6 @ meter reading that tells you to use f/5.6 @ 1/2501/250th,th, but you want a deeper depth of field. but you want a deeper depth of field. What would be a good exposure to get a deeper What would be a good exposure to get a deeper depth of field???depth of field???

Aperture SettingsAperture Settings

1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32,

Shutter Speed SettingsShutter Speed Settings

2’, 1’, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 2’, 1’, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000,1/500, 1/1000,

F/8 @ 1/125th F/8 @ 1/125th F/11 @ 1/60thF/11 @ 1/60th F/16 @ 1/30thF/16 @ 1/30th F/22 @ 1/15F/22 @ 1/15thth

All of these exposures would give you All of these exposures would give you an equivalent exposure and each an equivalent exposure and each aperture will give you a different aperture will give you a different depth of field. depth of field.

Have Fun Have Fun and and

Keep on ShootingKeep on Shooting