Photography is the art and science of recording light to create an image. A camera helps you choose what to include, how bright the photo should be, and how motion or focus appears. Learning the basics lets you make stronger portraits, action shots, landscapes, and creative project images.
It also connects to physics because every photo depends on light, lenses, sensors, and timing.
The three main exposure controls are aperture, shutter speed, and ISO. Aperture changes how much light enters and how much of the scene looks sharp, shutter speed controls motion blur, and ISO changes the sensor's light sensitivity. Composition tools such as the rule of thirds, leading lines, and framing help guide the viewer's eye.
Good photographers combine technical choices with creative goals, such as freezing a skateboard trick, blurring water, or making a dramatic low light portrait.
Key Facts
- Exposure depends on aperture, shutter speed, and ISO working together.
- Aperture is written as f-number, such as f/2.8 or f/11, where a smaller f-number means a wider opening.
- Shutter speed is the time the sensor is exposed to light, such as 1/1000 s for action or 1/30 s for blur.
- Doubling ISO, such as ISO 200 to ISO 400, makes the image about twice as sensitive to light but can add noise.
- Lens relationship: f-number = focal length / aperture diameter.
- Rule of thirds places important subjects near lines or intersections that divide the frame into 3 equal rows and 3 equal columns.
Vocabulary
- Aperture
- The adjustable opening in a lens that controls how much light enters the camera.
- Shutter speed
- The amount of time the camera sensor is exposed to light when taking a photo.
- ISO
- A camera setting that controls how strongly the sensor responds to light.
- Composition
- The arrangement of subjects, lines, colors, and space inside a photograph.
- Depth of field
- The distance range in a photo that appears acceptably sharp.
Common Mistakes to Avoid
- Using a slow shutter speed for fast action, which causes blur because the subject moves while the sensor is recording light.
- Raising ISO too high in bright scenes, which can create unnecessary grainy noise and reduce image quality.
- Centering every subject automatically, which can make the photo feel flat when a different composition would guide the eye better.
- Ignoring the background, which can distract from the subject with clutter, bright objects, or awkward lines.
Practice Questions
- 1 A lens has a focal length of 50 mm and is set to f/2. What is the diameter of the aperture opening in millimeters?
- 2 A photo is taken at 1/60 s. If you change to 1/240 s, how many times shorter is the exposure time?
- 3 You want to photograph a friend jumping in the air at sunset. Explain which shutter speed, aperture, and ISO choices would help freeze the motion while keeping the photo bright.