Camera built-in flashes / Flash attachments / Flash unit

Most modern digital cameras have a built-in flash. These flashes usually only provide inadequate performance (guide number +/-12). Additionally, there are further restrictions which make using other flashes a requirement.

Camera built-in flashes

Camera built-in flashes generally provide flat light as they are set to illuminate the subject head-on (frontally) from the camera’s direction. Small reflective areas are responsible for relatively hard light. Fact: the smaller the light source’s radiating surface is, the harder the light is. The poor reputation of camera built-in flashes has resulted in them being provided on hardly any professional cameras (are provided on nearly all digital cameras). A built-in flash used as an emergency source of light or a fill flash is not to be underestimated. Before an image is unintentionally blurred or underexposed, creative aspects of lighting have to take a backseat.


  • (If provided) always available


  • Flat light
  • Limited options to control flash
  • Relatively low performance level (guide number)
  • For extreme wide angle lenses the light angle may not be sufficient and may cast dark shadows on the border of an image.
  • Use of a lens hood and/or a large lens (e.g. telephoto lens) may cast a shadow from the fast.


Flash attachments / Flash units

Especially due the camera’s built-in flash’s poor performance, many photographers use a superior flash attachment (compact flash) or a flash unit. Depending on the guide number (varies from make to make from 30-60); there are flashes with reflectors mounted on a swivel mechanism which allow you to determine the direction of the flash. In doing so, you are able to e.g. indirectly cast a soft light on the subject. The use of extreme wide angles or respective lenses (see above) can also make using an additional flash crucial. System flash units or attachments that use TTL metering are almost as easy to use as camera built-in flashes.

Advantages (compared to built-in flash)

  • High performance (depending on make)
  • Limited steering of light possible due to reflectors and light shapers 
  • Possibility to use the flash separately from the camera
  • Less sensitive to shading caused by a lens hood or a lens
  • Wide beam angle (to achieve this, a diffuser often has to cover the reflector)

Disadvantages (compared to built-in flash)

  • Requires its own power supply (rechargeable batteries, batteries)
  • Additional device that takes up space and adds additional weight
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