Time to put things in clear order: All the terms related to exposure gathered on one page and how they are connected in a nutshell. With links to all more detailed pages around exposure.

White orchids with different exposure

Orientation map about exposure

Aperture, shutter speed, ISO – the controls for exposure

We start with three faithful companions who will be around you all the time in photography, today just as they have been through the decades of analogue photography:

  • Aperture
  • Exposure time
  • ISO sensitivity.

Each by itself has a certain effect on the look of your photos:

  • Aperture → Depth of field
  • Exposure time → motion blur and camera shake
  • ISO sensitivity → image noise.

All three together make up the exposure → the image brightness.

You can think of this as a kind of mixer with three sliders for image brightness. With each one you can increase or decrease the image brightness. And if you move one up, another one has to go down to keep the brightness the same.

Exposure metering and control – setting the sliders

overview chart with key terms around exposure

Exposure metering measures the brightness of the subject and then knows how far all three sliders in combination should be turned up.

You can leave this to the camera or have a say in it yourself:

  • Type of exposure metering → where in the frame should the camera measure the exposure?
  • Exposure lock → measure the exposure with a different image section than your later photo.
  • Exposure compensation → correct the result of the automatic exposure measurement upwards or downwards.

There are a several combinations of the three controls that provide the same image brightness and match the result of the exposure metering.

The exposure control picks one of the possible combinations of aperture, shutter speed, ISO sensitivity. Again, you can leave this to the camera or sit down at the mixer yourself:

  • With the camera mode you instruct whether the camera alone decides on aperture and shutter speed or what you want to do yourself.
  • You can select the ISO sensitivity yourself or let the ISO automatic adjust it up and down in a flash, depending on the camera mode, .

A guided tour about exposure

Here is the list of the more detailed pages on exposure. They form a circuit like a guided tour past all the sights on the map shown above:

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