DSLR and Film cameras don’t just have one metering mode, they usually have three or four different modes. How does one know which mode is most appropriate for any given situation?
As with most things related to photography, the answer is to know what each of these modes does. We start by understanding what a light meter does. Let’s look at what 4 of the most well-known camera metering modes do, and how you can use them.
We’re not dealing with Mirrorless cameras in this article, as they’re more advanced and have even more metering options. However, these fundamental modes remain the same. So, read on…
What Does a Camera’s Light Meter Do?
Your camera has a light meter (aka Exposure meter) built into it. This meter measures the light coming Through The Lens (TTL) and helps the camera (or you) to adjust your shutter speed, aperture, and ISO appropriately so that you get a well-exposed image.
Remember that a light meter by itself does not know what you want the photograph to look like. Its job is to make the picture 18% grey (aka Mid Grey). Today’s cameras have algorithms that understand what a camera’s sensor is looking at (for example a face). The algorithm prioritizes those areas over other areas of a photograph when setting exposure.
However, older DSLR cameras and film cameras did not do that. They either sensed how much light was coming into the lens overall, or how much was landing on specific areas of the frame. How the light meter reacted to these ‘zones’ of sensitivity determined which areas were given priority.
Let’s take a look at the various metering modes that you’re likely to encounter on a DSLR or Film camera in order of decreasing difficulty.
1. Spot Metering
Hand-held spot meters are expensive and very specialized. They read light from a very narrow angle-of-view; usually just 1 degree of view. Cameras replicate this functionality to some degree, by reading light off a very small area in the center of the focusing screen.
When Should You Use Spot-Metering on Your DSLR?
When exposure in a certain area is critical, and there is a lot of contrast in a scene. For example, when you’re shooting a concert, you may face very bright or very dark stage settings. If exposing for the entire scene, you may risk blowing out the artist’s face to an over-exposed white. However, you can meter off their face, and when set to manual, you’ll be exposed correctly most times. Most regular metering modes will have trouble getting the right exposure for just the artist’s face.
All you have to do is point the center dot at the spot that you want to be exposed correctly, set your exposure manually, and take your photograph.
What Else is it Good For?
It’s good for measuring the contrast range of a photograph and deciding your exposure based on multiple readings. You’d do this when you want to get really technical about your exposure, but for most people and purposes, it’s not necessary with today’s technology.
Level of Difficulty
2. Partial Metering
Partial metering is very much like spot-metering, but reads light from a 10-15% area around the center of the viewfinder. Unlike Center-Weighted metering, There is no weightage…
When should you use Partial Metering on your dSLR?
Use it in situations where you need to accurately meter an area of your frame that’s slightly larger than a 1-degree spot. It’s also useful if you need to average out the lighting in a certain region, but where the area that is under similar lighting is slightly larger. Useful in back-lit situations.
Level of Difficulty
3. Center Weighted Averaging
This is the kind of metering that most cameras had when I was growing up. It reads about 80% of the scene, giving more weightage to the center of the frame. This is because most people compose their photographs with the subject in the center.
Think of an oval area in your viewfinder with its edges almost touching the 4 sides. That’s the approximate area that this mode reads light from, but with more importance given to the center of the frame. Some manufacturers also add a little extra weightage to the bottom of the oval. I guess that they’re assuming that in a scene being photographed, the subject would not be pointing down from the sky. :P
When Should You Use Center Weighted Averaging metering?
Use this metering mode when you’re shooting with a more or less even lighting in your scene; for example, when the light is behind you, and you’re shooting with your subject in the center of your frame.
Most family and group pictures fall into this category. It’s an all-purpose light metering mode, but one that has now become outdated because of the invention of multi-zone metering systems.
Level of Difficulty
4. Multi-Segment Metering / Matrix Metering
Also known by proprietary names such as Matrix Metering (Nikon), Evaluative Metering (Canon), Honeycomb Metering (Minolta of old), and others…
Multi-segment metering divides up the frame into different parts, which are then evaluated for exposure separately and compared against a database of lighting situations that are stored in the camera’s processor. The camera then selects an appropriate exposure setting.
When Should You Use Multi-Segment Metering?
Today, the cameras we use are quite well-programmed, and for most purposes, there’s no need to ever take your camera off whichever Multi-Segment option your camera manufacturer provides. However, there are some lighting scenarios that prove to be too difficult for the camera to handle. Knowing this comes from knowing your equipment, and from using it often.
Level of Difficulty
Metering on Modern DSLRs and Mirrorless Cameras
Today’s cameras are very intelligent. They literally can detect what the lens is capturing in real-time.
For example, Sony and Canon mirrorless cameras have eye focus which allows the autofocus to lock on to features of a person or animal’s face. Canon’s R3 even detects cars and other automobiles. All this data also informs the camera about which areas are important and can be used to pick an exposure to favor these areas when used in automatic modes.
We’ll look into metering on mirrorless cameras in a future article, so subscribe to our email newsletter or social media to stay in the loop.
Want To Know More?
Let us know if you’ve got any questions about metering light for photography. Also, feel free to leave suggestions in the comments.
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Published: June 19, 2012 | Last Updated: August 16, 2021