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My Lightmeter Lies

April 22, 2012

Did you ever see a breathtaking scene that you just had to capture, only to find when you downloaded the pictures, they were very disappointing? Too dark, too light or just not as you “remembered” it. We all have and generally we blame the camera.  Did the light-meter just lie, or did you do something wrong? Sorry to lay blame, but unless the meter was broken (unlikely), it was probably your fault. Here, I am referring to cameras with inbuilt meters and they are all pretty reliable. However, they are dumb. All they can do, is take an average reading of the light being reflected from the scene and set the camera’s exposure accordingly. With strong back light, or sidelight or any spectacular light that is in some way uneven, they will get it wrong. It is up to you to help them. Thankfully, camera manufacturers have put in various modes to give the meter a better chance to get the exposure right. Most people don’t use these modes (or even know about them), to advantage. Let’s explore in more detail.

Multi-Metering The most general mode is named multi-metering, or matrix metering. Each manufacturer has their own terminology, but the way they all work is similar. They read the light from various areas of the scene, giving weight to different segments. More importance and exposure to the centre, and a bit less to the top, bottom and sides of the frame. Great in good light with an evenly lit subject. e.g. family groups, landscapes in daylight, centered subjects etc. Multi-metering won’t generally give you a bad exposure, but you won’t necessarily get a great one either, unless all conditions are average. This general setting is the one to use most of the time when the light is good and the subject well lit.

Center Weghted Shooting a portrait against a window? Here’s where centre weighting is the best choice. This mode gives majority of the exposure (60%-70%) to a fixed area in the the middle of the frame and only 30%-40% to the rest of the frame. Voila, the subject is lighter and you can see their faces rather than a silhouette. Naturally, the background may be too light, but the subject will be perfectly exposed. The size and strength of the area devoted to centre weighting varies by manufacturer, but it is the most effective method of setting exposure numerous cases. I mentioned backlit portraits in windows, but sidelit landscapes, sunsets, and subjects such as flowers all benefit from centre weighted metering. If your subject is looking too dark, change to centre weighted metering, your results will immediately improve.

Spot Metering This is the most specialised mode of all, but when you need it, it is a picture saver. It is simply a variation of center weighing, but with only a very small portion of the image area used to measure exposure. i.e. a spot. No exposure input is used from any other part of the image area. It is perfect for stage photography where you place the spot on the subject to measure only that light. In several of my cameras, the spot can be made to coincide with the focus point and shifted to allow focus an light measurement from the one position. Spot metering requires a little practice, but it can be a photo saver.

The next time you get frustrated by your “dumb meter,” ask yourself whether you helped it enough. Try changing metering modes. Your pictures will be much better for it and you will find your meter isn’t as dumb as you first thought.

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