Today, I will try to answer the question about exposure measurement. You’ve asked me a lot about the difference between center-weighted, spot, matrix, or evaluative metering. So, the first thing I would like to say on this topic is that in the majority of cases, it is an issue that is not important to you, that you don’t have to worry about. In most situations, leave on the default measure, which is therefore the evaluative or matrix measure, depending on the names of the different brands. The default metric, in the majority of cases, does its job very well.
So this is really in very special cases, and I myself, today, quite honestly, hardly ever use any other measuring mode than the default measuring mode.
So in the majority of cases it is part of what I call “overthinking”, that is, asking yourself too many questions before taking a photo, when in fact, we could just let the default choice and not bother more than that.
It must be said that there are certain settings that it is not essential to choose absolutely before shooting, so if you already choose the main exposure parameters, that is to say the aperture, shutter speed and ISO – even just two out of three – this is already more than sufficient in the vast majority of situations.
What is a measurement mode?
You should know that the camera, when you are in semi-automatic mode, therefore Program, Aperture priority and Shutter priority, as it is in these modes, to determine on its own which is the right one. exposure, it makes a measurement.
That is, he looks in front of him at what there is as light and he takes a measurement to determine what is going to be the right exposure. And for him, the right exposure is what we call a “medium gray” or “18% gray.”
So what is this gray? As the name suggests, it’s really a medium gray, it’s right between black and white, to give you an idea. In fact, this is what is supposed to cause an exposure for the eye, and therefore an overall brightness of the image which is harmonious in the majority of situations.
So in evaluative or matrix measurement, the default measurement, it will therefore measure this light over the entire image. That is to say, it will measure the light over the entire image and determine the exposure so that the average brightness is this famous medium gray.
So it will take into account the shadow zones, the light zones, etc., it will take into account the whole image and give you an exposure so that it is this famous medium gray.
So this is the default mode and in most situations, the device is doing very well. And besides, it improves quite a bit over time; with more modern and / or more high-end devices, in general the exposure measurement is even better and manages, we will say, to understand that certain parts of the scene are really very bright, but that it should not be take it into account, that’s it, it improves over time.
There are mainly two other measurement modes:
The spot metering mode : the spot metering mode will make the same measurement, but on a small part of the image. That is to say, the device will only take this part of the image into account to determine this famous 18% gray.
For example, if you do the spot metering on a very bright part of the image, it will expose that part, that is to say that this part will be in the middle tones, therefore pleasant to the eye, we will say to simplify as much as possible, and against all the areas that will be brighter or darker, it will not take into account at all.
They could possibly be well exposed, especially if they have the same brightness they will be well exposed too, since they have the same brightness, on the other hand if they are much brighter or much darker than the part you used, they will be either completely white or completely black, because the device will not take it into account at all.
So this spot measurement will be done, on some cameras, only on the central circle that you will see in the viewfinder, this is particularly the case with Canon cameras in general, and on some cameras, it will be done on the collimator that you will see in the viewfinder. you will use to focus.
So it really depends on your model, we can’t say a general rule about it. In general, at Canon it is in the center, at Nikon it is on the selected collimator, for reflexes, for hybrids it depends a little. On my hybrid, this is where we focus, so it’s more practical, it really depends on your camera, so that, I can’t tell you precisely, you have to look at your manual to find out if it’s in the center or on the collimator where you focus.
So that can be useful for you to expose well, for example if you have a subject which is in front of a window in broad daylight, the window will be very bright and it will be a little in the shade since it is inside, and you’re going to want to expose that subject well and make the background completely white, it might be useful to spot metering on that subject and make the background white.
If it is done on the center of the image only and you do not want the subject in the center, you should also use AE lock. I will not explain to you in detail in the video because it is a video which is meant to be short, but I will put a small link below the video to an article where I explain it in more detail. This is the spot measurement.
There is another metric called a center-weighted metric. So there, it’s not going to measure either on the whole image or on a small part, but it will in fact take into account both, but differently.
It will mainly take into account the center of the image, as on a spot measurement, but it will also take into account the rest of the image, but to a lesser extent. That is, it will still prioritize the small spot metering circle, but it will also take the rest into account anyway. He’s not going to completely forget about it.
In all cases, these different measurement modes are made to indicate to the device on which part of the image it must concentrate in order to determine the exposure. Check for more on dzofilm.com
So, you have this exposure lock tool to correct the camera if it ever gets it wrong in the exposure, if the image is ever too dark or too light, but it’s not, let’s say, the most practical tool, this measurement mode, because it is not necessarily very intuitive.
The most intuitive for me, and which I advise you to use in most situations, is still exposure compensation.
The exposure compensation is really very simple, if your image is too dark, well, you are going to tell the camera to brighten the image by putting towards the more, by telling it “expose the photo more, gives more light ”, and if the image is too bright, the other way around, well you’re going to do just the exact opposite. You will decrease this exposure compensation towards the minus by telling the camera “gives less light, makes the image darker”.
It’s really very simple, it’s very intuitive, and it seems to me a much easier tool to use, a lot less headache for you than asking yourself if you should change the measurement mode, etc.
Now I hardly ever use any metering mode other than evaluative metering, because it works well.
And if the camera ever gets it wrong, which happens regularly, not in most situations, but regularly, well, just make an exposure compensation. It’s really very simple, it works well, and it will save your life in any situation where the exposure is not the right one by default.
It really just do that, so I’ll answer anyway on the side “What metering mode does what”, but ultimately it’s a tool I’d suggest not specifically to use, especially if you do not understand very well how it works. Exposure compensation will be much more effective for you.