Midtones and Metering Modes: how to ensure an accurate reading

    | Photography for Beginners | 30/08/2012 17:57pm

    Metering Modes & Midtones: how to ensure an accurate reading

    When photographers talk about ‘taking a reading’ or ‘metering a subject’, they’re usually talking about taking a Spot or Partial meter reading from a specific area in a scene and locking the exposure in. This guarantees that the subject you’re metering for will be exposed correctly.

    However, you need to make sure that the area you’re taking a reading from is a midtone. If the area is dark in tone, and you don’t dial in ‘-’ exposure compensation to make it dark, this area will be set as the midtone, and the picture will be overexposed.

    If the area is bright in tone, and you don’t dial in ‘+’ exposure compensation to make it bright, then this area will be set as the midtone, and the picture will be underexposed.

    In our examples below we show you the effects of different metering modes and where within the frame you should take your reading.

    Evaluative metering mode

    1/100sec at f/22

    Evaluative metering
    Evaluative has done a good job here, although the highlights are slightly blown.

    How Evaluative metering gets it wrong
    Your Evaluative metering mode is reliable and accurate in the majority of day-to-day shooting situations. However, the exposure it comes up with is linked to the focus point (and AF points that have almost achieved focus), and this can cause problems if the subject in focus is very dark or very light in tone.

    The solution, as always, is to check the histogram, and dial in exposure compensation if required (What is exposure compensation? See our cheat sheet).


    Spot metering - highlight

    1/500sec at f/22

    Spot metering – highlight
    Taking a reading from the white area makes the picture underexposed.


    Spot metering - shadow

    1/30sec at f/22

    Spot metering – shadow
    Taking a reading from the black area makes the picture overexposed.


    Partial metering

    1/125sec at f/22

    Partial metering
    Taking a reading from the grass (a midtone) creates a balanced shot.

    Exposure and metering adjustments


    Capturing the optimum exposure in-camera is critical if you want to get the best-quality results, and whichever metering option you choose there will often be some room for improvement. Your DSLR has a wide range of features that you can take advantage of to ensure you end up with the best-possible exposure, even in the most demanding of lighting conditions.

    Exposure compensation

    Exposure compensation
    By rotating the Quick Control dial or pressing the ‘+/-’ button and turning the control dial (depending on the camera), you can apply compensation in 1/3 or 1/2 stop increments up to +/- 5EV. Reset to 0 when you’re done.


    AE Lock

    AE Lock
    Your AE Lock function enables you to lock an exposure setting independently from the focus, then re-frame the shot. Dab the shutter release to activate the metering system, fill the frame with the subject you want to meter, then press the ‘*’ button and recompose the shot.


    Exposure bracketing

    Exposure bracketing
    The auto exposure bracketing (AEB) function enables you to take three consecutive shots: one as-metered, one slightly overexposed and one slightly underexposed. You can set the bracketing increments, and use AEB in conjunction with exposure compensation.


    When to use spot metering
    Metering mode cheat sheet: how they work and when to use them
    44 essential digital camera tips and tricks
    Dial M for… Your exposure modes exposed

    Posted on Thursday, August 30th, 2012 at 5:57 pm under Photography for Beginners.

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