The light meter only updates after pressing the shutter button half way. Is it possible to show it before the shutter is half way pressed.

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  • Are you asking if the meter reading can be set to change while the shutter button is half-pressed (instead of locking in exposure)? Or if the meter can be set to remain active for longer after the half press is released? Also, are you asking about viewfinder shooting or Live View shooting? – Michael C Mar 23 '19 at 5:07

For metering to be active in any of Canon's EOS cameras, it must be initiated by one of several actions:

  • A half press of the shutter button
  • A press of the AE-L (auto-exposure lock) button
  • A press of the AF-ON (autofocus on) button (if the camera is so equipped)
  • A press of any other button mapped using the custom control menu to initiate metering

Once metering has been initiated, how long it stays active is also determined by several user selectable settings and whether one is using the viewfinder or Live View.

  • In certain metering modes, such as 'Evaluative', exposure is typically locked after initial metering as long as the shutter button is held down when in an automatic or semi-automatic exposure mode.
  • In other metering modes, such as 'Center-weighted Averaging', 'Partial', or 'Spot' metering, metering will remain active and continue to update until the shutter button is fully pressed (or metering times out). Exposure is not set until just before the picture is taken (with the exception of full 'Manual' exposure mode).
  • Metering will remain active (or locked) as long as one of the above listed buttons is pressed, until the picture is taken, or until the buttons are released and metering 'times out'.
  • Some Canon cameras allow the amount of time metering remains active after the shutter button is no longer half-pressed to be user selectable. Others do not offer this custom function and metering will 'time out' in about four (4) seconds after the shutter button (or other button listed above) is no longer pressed.
  • There's a separate setting for how long metering will be active in Live View. Options for several of my Canon cameras include 4 seconds, 16 seconds, 30 seconds, one minute, ten minutes, and 30 minutes.
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