Knowing how to use a light meter accurately is going to give you the edge when it comes to correctly exposing your photography.
The great thing about modern digital photography is we hardly need to do much. You could set every setting to Automatic, and let the camera do everything.
Is this the best way to photograph? Will this give you the best photographs possible? Well, no and no. Just because it’s possible, doesn’t mean we should do it.
One thing that our camera does so well is meter the light. When you look through the viewfinder of your DSLR, your settings are presented to you in tiny seven-segment indicators.
Somewhere in that finder, usually at the bottom, is the EV Scale. This, with the help of the focus button, will tell you if the scene is over-exposed, under-exposed or just right.
What Is a Light Meter?
Some scenarios and settings have complex levels and amounts of light. This is where the metering modes come into play.
This will depend on what metering setting you currently use on your camera. These are:
- Matrix metering – Here, the camera looks at the light in the entire scene and averages it.
- Center-weighted metering – Here, the camera looks at the light of the entire scene and averages it, emphasis on the centre.
- Spot metering – Here, the camera measures the light only in a small area around the central autofocus point.
- Partial metering – Here, the camera measures the light only in a small portion of the centre of the frame, slightly bigger than the spot meter.
These are important, as each metering mode looks at the scene in different ways, and makes its evaluation based on these modes.
You will find it complicated to get the exposure you want if these metering modes aren’t set correctly for your scene.
Before digital photography utilised these light meters in-camera, they were stand-alone devices. Handheld light meters helped analogue film photographers nail that perfect exposure.
Studio photographers still use them today to make sure their capture has the correct exposure. It’s also a great way to find out where the ‘hottest’ point of the subject is in very complex studio lighting situations.
For advice on which light meters are avaliable, read the article here.
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Types of Light Metering
Most cameras today use TTL Metering, which stands for through-the-lens. Here, our camera examines the light coming in via the lens and evaluates the brightness of the scene. Your DSLR only uses one of the two options available.
A light meter is different as you can move it around, and its only purpose is measuring the light.
There are two different types of light metering that a hand-held light meter will detect. One is looking at the incident light, and the other is the reflective light.
Incident Light Meter
An incident meter reads the amount of light falling on the subject. This can be natural light, coming from the sun, or an artificial light, such as a flash or strobe.
You hold the light meter in between the subject and the light source, as close to the subject as possible. The white dome on the device is what picks up the light reading.
By metering this way, you will disregard how light or dark your subject is. This helps to eliminate errors caused by lighting a subject from behind. This type of metering is not capable from an in-camera light meter.
Reflective Light Meter
A reflective light meter records the light levels reflected by the subject. The natural or artificial light will leave its source and bounce off the subject.
A DSLR’s light meter looks at the reflective light as that is the light that travels through the lens, hitting the sensor.
Different types of reflective meters are used, based on how much of the frame is metered:
- Matrix or Evaluative Metering breaks a frame into zones and uses an average to judge exposure.
- Center-Weighted gives the centre of the frame the most importance when measuring.
- Spot Metering looks only at a small area of a frame (where you place the focal point) to measure exposure.
Your hand-held light meter can switch between these modes well. On some models, such as the Sekonic L-308S-U, it is just a simple matter of sliding the dome from covering the sensor.
In addition, handheld light meters can read a much smaller image area than that of an in-camera light meter.
How To Meter Landscapes
An incident reading is all you need for a perfectly exposed landscape photograph. The typical way is to hold the light meter out in front of you and the camera.
Press the meter button. Read the results given to you, and set your camera’s settings to match. Now you are ready to accurately expose your scene.
You want to capture the same light hitting the scenery in front of you. As long as the light is the same, you don’t need to go traipsing to all the points in your frame.
Try not to get direct sunlight on the dome, as that would create an underexposed image. If you are capturing direct sunlight, try to cover the dome with some shade for the best reading.
For this, you need a light meter that has the capacity to spot meter. The Sekonic L-758DR-U is a perfect choice if you can find it or afford it.
When looking at the scene, you want to take at least three different readings. The darkest shadow area, the brightest highlight area, and the mid-tone areas.
These need to be committed to the light meters’ memory bank, done by pressing the memory button after each exposure.
The average button will then create an average out of the three pieces of data, giving you the settings for your camera. Hello, perfect exposure!
This technique allows you to take in a lot of light information from different areas. It can be quickly processed without boring, manual calculations.
Once you get the hang of the differences in the light intensity, these readings will happen faster and faster.
How To Meter Portraiture
In portrait photography, a light meter is an invaluable tool. Just hold it in front of the subject’s face, pointed towards the light source.
And you’re done. You now have the settings for your camera. Just make sure the lumisphere is covering the light meters’ sensor.
This reads for middle grey. If you would prefer a lighter image, just expose one stop higher than the reading.
Here, you are again trying to formulate an average exposure. This is for a standard image where an average exposure of the scene is wanted.
Complete the reading for the darkest, lightest areas and the mid-tones, committing each to memory. Create the average to get the settings for your camera.
For something a little more high-key, just read the lightest areas of the subject. This will force the rest of the image to become darker, as the settings are not averaged out over the entire scene.
A note from Josh, ExpertPhotography's Photographer-In-Chief:
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