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2.4 - Confusing Terms >

General Terms

Overexposure & Underexposure


An underexposed photograph is too dark—too little light reached the sensor.


An overexposed photograph is too light—too much light reached the sensor.

The terms below are even more confusing because their meaning changes depending on their context.

Fast & Slow


Fast Slow

ISO is a rating of how sensitive a sensor is to light. A fast ISO is more sensitive to light. It has a larger ISO number.

A slow ISO is less sensitive to light. It has a smaller ISO number.


Fast Slow

A fast lens has a large lens opening, such as a f/2.8 zoom lens.

A slower lens has a smaller lens opening, such as f/4.

Shutter Speed

Fast Slow

A fast shutter speed lets less light reach the sensor.

A slow shutter speed lets more light reach the sensor.


Wide Lens Opening

A wide lens opening is a large lens opening, such as f/4. The lens opening is physically wide or large.

Wide Lens

A lens that "sees" a wide angle of view.

Opening Up & Closing Down

The Lens Opening

Opening Up

When you open up the lens opening, say from f/16 to f/11, you're letting more light into the camera.

Closing Down

If you close down the lens opening, such as from f/4 to f/5.6, less light is reaching the sensor.