When taking photos with your mobile camera in Manual mode, there’s a setting that very few mobile photographers pay attention to-- metering.
Although some may deem it unnecessary, metering can help you control exposure and take awesome photos in various lighting situations.
First, let’s look at…
What is metering?
Metering is your camera’s best guess as to what the appropriate exposure for the scene should be depending on the metering mode selected. This is based on the amount of light that appears to be in the scene.
Basically, metering refers to the measurement of light in a scene in order to set the appropriate exposure. Light is measured with photographic light meters, which fall under two categories: reflected light meters and incident light meters.
Incident light meters are hand-held devices that measure the light that hits the subject directly. Reflected light meters measure light reflected from the subject to determine how much light is hitting the subject.
Not surprisingly, incident light meters are more accurate and used prominently in professional photography.
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Some digital cameras have built-in light meters which, by default, are reflective light meters. Others including smartphone cameras measure the amount of light that hits the sensor based on reflected light.
Although not as accurate as measuring incident light, reflected light metering can be useful provided you understand its shortcomings.
How does metering work?
Smartphone camera light metering measures reflected light. This means that based on the camera’s analysis of the scene, it guesses how much light is hitting the subject and illuminating the scene.
Depending on the metering mode selected, the camera will analyse that portion of the frame and determine whether the shot is overexposed or underexposed.
Based on its calculations, the camera will adjust the exposure settings to better suit the selected metering area.
Each metering mode focuses on a specific area of the frame, so you can pinpoint precisely which area you want to have exposed. By default, most camera apps with Manual mode are set to analyse a large portion of the frame.
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Advantages of metering
If you’re new to shooting in Manual mode on your smartphone and are not familiar with the ideal relationship between ISO and shutter speed, then it would be useful to use metering.
The meter will provide you with the best setting to achieve the exposure you want.
To better understand the relationship between ISO and shutter speed when trying to get the correct exposure, I recommend you read up on the exposure triangle.
Understanding how it works can help you greatly improve the quality of your mobile photographs.
Problems with metering
As helpful as metering is, it only works well when the lighting is even. The minute you have differing light levels and intensities in the same shot, it becomes very challenging for the light meter to determine the best exposure settings.
By default, camera meters are set to read and analyse light levels of the entire frame. If there are many objects in the frame that are dark and bright, the camera will try to find the middle ground, although it might not be the best setting.
Metering modes
In the metering section of your camera app’s manual settings, you’ll find three metering modes. Each one of them has its own way of evaluating the contents of the frame and set the ideal exposure for you.
Spot metering
Spot metering is the most precise of the three metering modes. When this mode is engaged, the camera only evaluates the exposure around your focus point and nowhere else in the frame.
Spot metering works well for back-lit subjects because of the small area it evaluates. If matrix metering or centre-weighted metering were used, the subject would be a silhouette.
When to use
You can use this mode for smaller subjects. For example, if you were taking a photo of someone and they had the sun behind but they only occupy a small part of the frame, you can use spot metering to get the correct exposure just for the area where they are.
Centre-weighted metering
Centre-weighted metering is concerned with exposing for a fairly large area in the middle of the frame. Everything else that is far to the sides and the corners of the frame is ignored.
What’s more, centre-weighted metering does not take into account where the focus point is, it only evaluates the area in the middle of the frame.
When to use
Centre-weighted metering should be used when your subject fills up the majority of the frame such as in the case of close-up portraits.
Also, this works well for exposing the subject’s face if you’re taking a headshot of a person with the sun behind them. The downside is everything else will probably get very overexposed.
Matrix/Evaluative metering
By default, most smartphone cameras are set to matrix metering. With matrix metering, the camera calculates the amount of light in multiple areas of the frame.
The frame of the camera is divided into zones and, depending on how much light is in these zones, the camera will calculate the average brightness and adjust the overall exposure accordingly.
The most important factor in matrix metering is the focus point. After analyzing the light information in all the zones of the frame, the metering system will look at the area where the focus is set and regard that as important.
But because this mode is evaluative in nature, the contents of the rest of the frame will have an impact on how the focal point is exposed.
Other variables that are evaluated in this type of metering are the distance between the subject and the camera, the colours in the scene, highlights, etc.
When to use matrix metering
When exposure is not going to be a problem and you have a broad subject matter to include in your frame, then this is an ideal metering mode to use.
How does a smartphone camera estimate exposure?
Remember, smartphone camera sensors are colour blind. They see everything in black and white, and various shades of grey. Halfway between absolute black and absolute white is middle grey, which reflects 18% light. This is why it’s sometimes referred to as 18% grey.
Digital camera meters are calibrated at 18%. In other words, when a camera comes across a scene that is below middle grey, it will regard it as underexposed and lift up the exposure.
If the light meter reads it as above middle grey, it will bring down the exposure because it believes the image is overexposed.
When using evaluative or matrix metering, the total brightness of the entire scene should be around 18% or middle grey. With spot metering and centre-weighted metering, only the area of interest needs to match up to middle grey.
As mentioned before, smartphone cameras don’t have built-in light meters. Instead, the rely on the light intensity information from the pixels on the sensor.
After evaluating this info, the camera then adjusts the exposure settings according to metering mode chosen.
How to change the metering mode
To change the metering mode of your camera, you need to switch to the Manual mode of the camera app. This is also known as Pro mode on some devices.
You will recognize the metering mode icon usually by a rectangle with a circle in the middle or any other metering icon.
Exposure compensation
As mentioned before, incident light meters like the ones used by smartphone cameras are not accurate. So, it’s easy for them to get the calculations wrong and over- or underexposed.
If this happens, you can use exposure compensation (EV) to increase or decrease the exposure by a couple of values. This is a very useful setting that can be found in the Manual mode of your camera app.
If you don’t have a Manual mode on your camera app, then you need to download an app that does. Being able to manually control the camera’s settings as the pros do is definitely one of the reasons why you should shoot in Manual mode.
If you’re not familiar with Manual mode and all the settings in there, then check out this complete and comprehensive guide to manual mode.
If you want to learn about how to improve your smartphone photography, download the 5 Ways To Improve Your Smartphone Photography ebook by clicking on the banner above or by clicking here. There’s a lot to learn in its 22 pages of content and it’s ABSOLUTELY FREE!!!
Otherwise, for some quick tips on how to capture great photos with your phone, check out these 15 Tips on How To Take Amazing Photos With Your Phone.
