Pillars of Photography Shutter 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 Speed Questions?

Break 15 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.

Bringing 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.

Grain is significantly reduced due to the lower ISO. Up Close Grain 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.

ISO Questions?