Pillars of PhotographyShutter Speed and ISO

Shutter Speed

Controls how long the camera’s “eye” is open.

Measured in fractions of seconds, minutes or hours 1/60th of a second, 1/2000th of a second, etc

Fast shutter speeds will literally stop motion. Water drops can be caught in mid air

Slow speeds will cause motion to blur Water in a stream can be made to look like

milk.

Types of shutters

There are three basic types of shutters Electronic Shutter

No moving parts, the sensor simply applies power when the release is depressed and begins to record the image for the amount of time specified by the cameras computer.

Leaf Shutter Often referred to as an Iris, or Diaphragm

Shutter; this mechanical device copies the action of your eye through overlapping metal leaves.

Normally employs an odd number of leaves. (3, 5, 7 , etc)

Types of shutters

Focal Plane Shutter Most commonly used with DSLR, (Digital Single

Lens Reflex), Cameras. When release is depressed, the Front, (or First),

curtain moves over the sensor until it is fully open.

Once the shutter has been open for the desired amount of time, the Second, (or Rear), curtain begins to move until the sensor is again fully concealed.

Advanced shutter control is often called “First Curtain Sync”, or “Second Curtain Sync”

Long shutter speed

•Often referred to as a long exposure

•Normally requires a tripod

•Allows for deep depth of field

•Captures motion as motion

•Normally requires a smaller aperture (F16 –

F22 for example)

Fast shutter speed

•Can be easily hand held•Allows you to stop motion•Normally uses a wider

aperture (F2.8 – F 5.6 for example)

•Normally will result in a shallower depth of field.•Often used in sports or

action shots.

Shutter SpeedQuestions?

Break15 minutes

ISO (ASA)Speed vs quality

What does it mean

ISO, is an acronym that stands for the International Standards Organization. It was formerly known as ASA, (American Standards Association).

This is an expression of how sensitive a sensor, or film, is to light. Normal expressions are:

100, 200, 300, 400, 500, etc, etc Each step is twice as sensitive to light as the last. Problem with higher ISO is greater incident of grain in

your image. Lower ISO generally makes for a cleaner image.

High ISO

Pumping up the ISO value will make your sensor more sensitive to light, this will allow you to take pictures in darker areas without the need of a flash. This is useful in sports arenas, birthday parties and

museums where using a flash is unwelcome, or of no use.

The price you have to pay for a higher ISO is that your image will be more grainy. Modern digital cameras are making headway

regarding this issue, however a difference can still be detected by the human eye on 90% of high ISO shots.

Advantages of High ISO

Higher ISO will allow you to use a faster shutter speed. Useful if you do not have a tripod, or you are at a

sporting event where the use of a tripod is impractical.

Taking pictures at a birthday party when they are blowing out candles; a flash will ruin a shot like this.

You intentionally want the grain in the shot for artistic reasons.

Taking pictures in a confined area where only hand holding will work and flash will be too powerful. i.e: Home inspection of an attic.

Example of High ISO

• Shot in mixed light• Animal was moving quickly, so higher ISO was needed to support higher shutter speed at lower light.•Settings:• ISO: 400• Shutter Speed: 1/2000 • Focal Length: 200mm• Aperture: F4

This could normally be accepted as a decent photograph, look closer, the higher ISO shows itself.

GrainBringing the image to

100% shows the grain in the image.

This amount of grain is often deemed “Not

acceptable” by most professional

photographers, however to someone not in the field, they would likely not care

unless they had something to compare it to.

NORMALLY, this amount of grain would not be as

visible in a physical print.

Slower ISO

You will require a longer shutter speed, as the sensor or film is not as sensitive to light.

Depending on your situation, a tripod or other support will be needed or else your image will be blurry. Your heartbeat can be enough to blur a shot.

Cleaner image, less grain.

Not always the best choice for moving objects.

Advantages of Slower ISO

Better detail

Some cameras may find better color (Not always)

Little or no grain.

Using a tripod will allow you to gain massive depth of field for landscape shots

Useful for making star trails or light painting

Best for reproduction or art shots.

Slowing it down• ISO: 100• Focal Length: 135mm• Shutter speed: 1/30th of a sec• Aperture: F 5.6

Clear and tack sharp, the lower ISO allows for much finer grain and recording of detail.The cost of that detail is the speed of the shutter, this image had to be shot at 1/30th of a second, which is too slow to hold by hand, even with the use of strobes.Let’s take a closer look.

Up CloseGrain is significantly

reduced due to the lower ISO.

Detail is much sharper.The price to be paid

however is a shallower depth of field as we needed to open the

aperture to get as fast as 1/30th of a sec.

Any slower and the subject would likely have blurred due to breathing

or blinking.

ISOQuestions?