Photography Reference
A practical reference for exposure, lenses, focus, composition, color, and digital image files.
Updated 2026-08-12
Exposure
Exposure describes the amount of light recorded by the camera. Aperture, shutter speed, and sensor sensitivity are commonly adjusted together, but each also changes the appearance or quality of the image.
| Control | Primary effect | Common tradeoff |
|---|---|---|
| Aperture (f-number) | Controls the lens opening and contributes to depth of field | Wider apertures admit more light but may reduce the in-focus range |
| Shutter speed | Controls how long light is recorded and how motion appears | Long exposures increase motion blur and camera-shake risk |
| ISO setting | Changes the camera signal gain or output brightness target | Higher settings commonly reduce usable dynamic range and increase visible noise |
Lenses and Field of View
| Term | Meaning |
|---|---|
| Focal length | An optical property of the lens that, together with sensor size, determines field of view |
| Prime lens | A lens with one fixed focal length |
| Zoom lens | A lens whose focal length can vary across a stated range |
| Angle of view | The angular extent of the scene recorded by a particular lens and image format |
| Perspective | The apparent spatial relationship between objects, controlled primarily by camera position |
| Crop factor | A comparison between a sensor format and a reference format, often 35 mm full frame |
Focus and Depth of Field
Depth of field is the range of distances that appears acceptably sharp. It depends on aperture, focus distance, focal length, image format, output size, and the chosen sharpness criterion.
Autofocus modes are generally optimized either for a stationary subject, continuously changing subject distance, or automatic selection between those behaviors. Manual focus remains useful when contrast is low or precise focus placement matters.
Composition and Light
| Concept | Practical use |
|---|---|
| Visual hierarchy | Use placement, scale, contrast, color, and focus to make the intended subject clear |
| Leading lines | Use edges or repeated forms to guide attention through the frame |
| Negative space | Leave deliberate open space to separate the subject or convey scale and mood |
| Hard light | Produces relatively crisp shadow transitions from a small apparent source |
| Soft light | Produces gradual shadow transitions from a large apparent source |
| Dynamic range | Describes the span between recordable dark and bright tones before detail is lost |
Color and Digital Files
| Term | Meaning |
|---|---|
| White balance | An adjustment that maps the scene illumination toward a chosen neutral color appearance |
| RAW | Camera-specific sensor data requiring processing before ordinary display or delivery |
| JPEG | A widely supported lossy image format, normally produced after in-camera or desktop processing |
| Bit depth | The number of encoded tonal values available per channel or sample |
| Color space | A defined model and gamut used to encode and interpret color values |
| Metadata | Information stored with the image, such as capture settings, time, rights, and location |