Most DSLR’s will give you some different options for metering for the light in your image, and the results you get can vary tremendously depending on which metering mode you use! That's why understanding the different metering modes available and how they will affect the exposure of your final image is so so important.
What is Metering?
Metering is simply our camera trying to gauge the amount of light in the scene, so it can set the correct exposure. Regardless of whether you shoot in AUTO, a semi automatic mode, or in full manual mode, you will still use your in-camera meter for assessing exposure, and knowing how it works can help you get your exposure right first time, instead of having to continually 'chimp" and assess your exposure by eye.
(By the way, you cannot change your metering mode when you are still in AUTO, so it's yet another reason to learn how to move away from AUTO settings ! Go on, you know you want to)
Let’s start by having a closer look at the three main metering modes that both Canon and Nikon have. The yellow shaded areas in the pictures below represents the area that the camera meters for.
Evaluative (Canon) / Matrix Metering (Nikon)
This will be the default setting on most cameras. It basically takes all the pixels present in the entire scene tries to even them out. It’s like AUTO for metering! As with shooting in AUTO mode, this can be great, since the camera is pretty much making all of the decisions for you, but the downside is that in tricky light, you aren’t likely to get your exposure right since not all scenes will "even out" - for example if you had bright light behind your subject, the camera will end up giving you an underexposed image. Remember, your camera is just a piece of equipment and can't read and see light in the same way we do, all it can do is make an educated guess.
That said, it can be a good all-rounder and is probably the easiest to use, but the downside is, it gives you the least control. If you are shooting in Manual Mode, and you have a good feel feel for how your camera's meter actually works, you can use this in some situations, knowing that you will need to expose "over" or "under" - but you do need experience for that!
Centre-Weighted (Canon & Nikon)
In this mode, the camera gives more weight to the tones in the centre of the image although it will also take some information from the outer meter points. It’s probably easier to predict how the camera will react using this mode (rather than evaluative) but the area it meters for is still quite large, so whilst it will give a better result in some situations, it's not the ideal mode. It's basically a "middle ground" option.
Personally I'm never a fan of middle options - although they seem like the best of both worlds, they rarely are :)
Spot (Canon and Nikon)
This mode tells the camera to meter from a very small specific area of the scene (around 3% of the frame) Therefore instead of judging exposure based on the entire scene, it just focuses it’s metering on a very small spot - in portrait photography this will be the person (just a small element of them in fact!). This helps the camera by pinpointing EXACTLY the area that you want the camera to expose for. It is the most precise and gives you the most control over the exposure of your image by far. This means that your metering becomes more accurate from the get-go, and you will have less twoing-and froing to get your image correctly exposed.
In some camera models you may also have a PARTIAL metering mode (or you may have this but not SPOT metering) This works in the same way as SPOT metering, but the area of the scene it meters from is larger - up to 15%. So, if you find you don't have SPOT, you'll have this instead.
So, which metering mode should you use?
Although you might want to stick with evaluative to begin with – it’s a good all rounder and will work quite well in the majority of scenes - it will be better to move onto Spot Metering as this will give you a better “reading” and allow you to get your settings right much quicker. It will also allow you to be more creative in your shooting, for example creating a silhouette. For those reasons, when you are happier with manual mode and metering in general, I would suggest moving onto spot metering as your default metering mode. Although this may be also more difficult to use to begin with, the payoff is you rarely then need to make any big changes from when you take your test shot, as it will be very close from the start! As I said earlier, once you have a good understanding of how your camera is likely to react to certain scenes, you can absolutely switch back to evaluative from time to time!
If you are not sure about how to shoot in manual mode then you might want to check out Auto to Awesome - it's a step by step program for taking control of your camera that really breaks this all down (and more!) down for you.
How to change your metering mode
If you want to change your metering mode, it's pretty simple to do! Here's how to do it on a Canon, but the process is similar on a Nikon, it just looks a bit different.
- Press the Q for Quick Settings and find the icon that looks like the ones below, and select it.
- Use the main keys or dial to switch between the available metering modes (you may have more than these three available)
- Press the "SET" button to make the change.
That's it! You can now practise on your new metering mode - have fun!