When working in a light-sensitive medium such as photography, it’s pretty imperative you have a firm understanding of how light works. From your camera’s in-built meter to using handheld light meters, find out how to read light to get the most out of any photography scenario.
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Handheld or external light meters are fairly uncommon these days as a camera’s in-built light meter has improved its performance capabilities drastically in recent decades. With that being said, there’s still plenty of studio and film photographers who put their faith in a handheld light meter because of its supreme ability to calculate the perfect exposure.
Let’s learn a little bit more about what a light meter actually does and why you should use one.
How Does a Light Meter Work?
A light meter is used to measure light in a scene in a number of ways. This can be ambient light, reflected or direct light. The light meter, being the ingenious piece of technology it is, takes all the guesswork out of the equation, calculating the appropriate shutter speed and aperture values in order to capture a correct and balanced exposure.
Historically, handheld light meters are used for studio photography to ensure supreme accuracy in a controlled lighting environment, or by landscape photographers hoping to achieve a wide dynamic range.
But you’re probably most familiar with the light metering modes available to you on a digital camera set-up. Depending on your camera manufacturer, these typically include the following:
1. Centre-weighted average metering: This mode prioritises the most important element of the scene, as the camera assumes its positioned centrally within the frame.
2. Spot metering: Your camera will only measure the light of a very small part of the scene in spot metering, most commonly between 1% and 5% of the viewfinder image.
3. Partial metering: This mode works similarly to spot metering but will measure a larger (but not that much larger) portion of the scene, somewhere around 10%.
4. Evaluative, matrix or pattern metering: These are all names for the same metering technique (depending on camera manufacturer), which is similar to centre-weighted averaging but takes into account other factors including the focal point and other elements in focus within the scene.
The above interchangeable modes for metering light can be referred to as TTL metering (Through-The-Lens), whereby the reflected light of the scene is measured through the lens.
The in-built camera TTL metering systems are incredibly reliable, raising the argument that handheld light meters are outdated or redundant. But photographers choose this slower technology for very good reasons, the predominant reason being that full creative control is easy with a handheld light meter, and that you (or rather your camera’s TTL metering) won’t be fooled by tricky lighting situations.
Types of Handheld Light Metering
INCIDENT LIGHT METER
Incident light metering is perhaps the most common method. Maybe you’ve seen another photographer hold a light meter right up to a subject’s face? What the photographer is doing is measuring the light falling on the meter. For an accurate reading, the bulb of the light meter is pointed back at the camera. See diagram below for further explanation. Incident metering is often referred to as ambient metering.
REFLECTIVE LIGHT METER
Whereas incident light metering measures the light falling on your subject, reflective light metering, as it sounds, measures the amount of light reflecting off your subject. Reflective light metering is the approach all TTL methods utilise in-camera.
Spot metering allows you to measure a very, very small portion of a scene to correctly expose for a certain area i.e. the cheek of a portrait subject. Particularly if the subject is backlit, the camera can confuse the contrast within the scene and mistake the correct exposure.
Spot metering is also used outside the studio in landscape photography. A landscape photographer may take several different spot meter readings of shadows and highlights and midtones to calculate an average exposure time.
A spot meter is a specific type of handheld light meter with an eyepiece for pinpointing your desired reading location.
How to Read a Light Meter
Light meters are pretty user-friendly devices. Seeing as you’re proficient in the language of f-stops and shutter speed fractions, you’ll really only need to familiarise yourself with the functionality of the handheld light meter, which changes depending on make and model. Common features include setting aperture or shutter speed priority, as well as ISO and flash compensation.
Best Light Meter for Photography
The best light meter depends on your needs as a photographer. Most photographers will find that the TTL light metering is perfectly suitable to their style of photography. Some professional photographers however, may find that a handheld light meter is required for complete precision in the studio.
That being said, if you are going to purchase a handheld light meter, we advise investing in reputable brand names like Sekonic. Check out the Sekonic L-858D Speedmaster. Nearly all light meters include incident and reflective metering options while more advanced devices have the added benefit of spot metering, such as the Sekonic mentioned above.
Best Light Meter Apps
Light meters, though useful, can be particularly expensive to introduce to your photography kit. Fortunately, there’s a number of free light meter apps available on iOS and Android worth downloading and experimenting with. Most of these apps are tested against traditional Sekonic or similar light meters to ensure the utmost accuracy.
iOS: LUMU LIGHT METER
Lumu is a very popular app for iOS that uses your phone camera as a reflective light and spot meter. An app such as this is a must-have for film photographers who don’t (or can’t) rely on any in-built metering system. Simply set your ISO or ASA, and see what aperture and shutter speed settings are recommended.
Lumu also has the ability to measure incident light, colour temperature and flash with the addition of the Lumu Power, a nifty little external light meter that plugs into your phone.
Get it on the App Store for free here.
ANDROID: LIGHT METER – FREE BY WBPHOTO
This app for Android systems is of equal user-friendliness as Lumu for iOS. Offering both reflected light metering with spot metering and incident light metering (with the plug-in), Light Meter by WBPhoto is a state-of-the-art photography tool. In addition to all the light metering functions, the app also has the added benefit of a Sunny 16 Calculator and even a Depth of Field Calculator.
More than 500,000 downloaders can’t be wrong. Search “Light Meter – Free by WBPhoto” in your Android app store.
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