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Photography basics: Exposure triangle, RAW and JPEG

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tagsglossar, foto, medien

2 min read

Photography basics: Exposure triangle, RAW and JPEG

In short: The exposure of a photo depends on aperture, shutter speed and ISO; RAW stores all sensor data for later editing, JPEG a finished processed image.

In more detail: Whether smartphone or SLR camera: photos arise from light falling on a sensor. Three settings control how much light arrives and how the image looks.

In Depth

The exposure triangle

  • Aperture (f-number, for example f/1.8, f/8): opening of the lens. Small number = large opening = much light, shallow depth of field (blurred background, portraits). Large number = little light, large depth of field (landscape).
  • Shutter speed (1/1000 s, 1/60 s, 2 s): how long the sensor collects light. Short = movement frozen (sport); long = motion blur, needs a tripod; rule of thumb against camera shake: time ≈ 1 / focal length.
  • ISO (100, 400, 1600 …): sensitivity/amplification. Low = clean; high = brighter but image noise. If you change one value you must compensate with another: doubled light = “one stop”.

More basics

  • Focal length (wide-angle, normal, tele): image section and perspective.
  • White balance: colour temperature (daylight, artificial light), otherwise colour cast.
  • Focus (autofocus, focus area), composition: rule of thirds, lines, framing, foreground, light (soft light in the morning/evening, “golden hour”).
  • Smartphones compute a lot (HDR, night mode) and combine several shots.

RAW or JPEG?

  • JPEG: the camera processes the image (sharpness, colour, contrast) and compresses lossily; finished, small, little room for corrections.
  • RAW: raw data of the sensor (more dynamic range, 12 to 14 bit); huge, must be developed (Lightroom, Darktable, RawTherapee, Capture One), allows strong correction of exposure, white balance, shadows/highlights without quality loss. Saving both in parallel is common. Formats such as HEIC/DNG exist on smartphones.

Tips and rights

Practise with semi-automatic modes (aperture priority A/Av, shutter priority S/Tv), look at the histogram, shoot a lot and cull. Back up (3-2-1) valuable photos. Right to one’s own image: publish people only with consent; children especially sensitive; remove location data (EXIF) before sharing. Copyright: your photos belong to you, others’ only with licence.

See also: Raster and vector graphics, JPEG, Right to one’s own image, Backup strategy