Knowing how to read the scene to be photographed, understanding how the flashmeter or light meter works, knowing the exposure metering modes and determining which one is the most appropriate at each moment can make the difference between an incredible photo and an unusable one. Read on to learn how to find the right exposure in all of your photos.
We will now see the most common types of measurement that can be found on cameras with a certain ability to trigger manually. In the options menu, generally appear the symbols or numbers similar to those which we will present below.
The types of measurement offered by the camera
This exposure metering mode takes into account the brightness of the entire scene, so it seeks to achieve an average reflectance of 12%. If we observe the scene to be photographed and we notice a relatively uniform luminosity (or reflectance), we can use this mode without worry.
For what we have explained, it will work particularly well in outdoor situations, with a sky that will not be predominant but also in other situations with an average (neither low nor high) and homogeneous reflectance. It will be just as adequate when we want to balance the light between shadows and lights, even if it will be impossible to obtain information on the whole image if the difference is important. For backlighting, high key or low key photos, etc. the result will probably not be what we expected. Regardless, it’s a very handy mode that works in many situations. This is the measure the camera uses when triggering automatically.
See an example below where this mode found the exposure perfectly. As the tones were fairly even throughout the image, matrix metering had no problem giving the image the correct exposure.
To take the measurement, this mode takes into account the brightness of the whole scene but gives more weight to the central part (30% for the periphery, 70% for the center, approximately). It is indicated when the background can distort the measurement. The more typical example to illustrate the use of this type of measurement is the portrait of a face. We want it to be well exposed, before the background, so we will give it more importance when measuring. The center-weighted measurement will therefore be ideal when you want to make sure you have a well-exposed model.
As an example, we photographed a model against the light in front of a window, in the image below. As we wanted the face to be black, for an exterior landscape appearing in the window well exposed, we then opted for the weighted measurement at the center by taking the measurement on the window since the area it occupies is significant, compared to the entire image. By triggering with matrix metering, since the dark area takes up a lot of space, the contents of the window would have been overexposed and the shadows would have presented detail, something that was not wanted on this occasion.
With this measurement, only one “point” of the scene is taken into account. A point is understood to mean a very small area with respect to the entire image, of the order of 5% of the total area of the scene. The closer we get to the object, the more precise we will have. The measuring point corresponds to the point chosen next for focusing.
This measure is strongly recommended if you have the time and want to work in zones. It is also a good measure to apply a rectification technique which consists in underexposing the brightest point of the scene by one or two stops to generate an image with the maximum information. With this technique, the final exposure adjustment is made during digital development. And point measurement is especially appropriate to ensure that an element of the photo will be perfectly exposed , no matter how small on the composition, such as the light of a candle, the white of a wedding dress, etc..
This mode is most often used by many expert photographers because it allows maximum control and great precision on the measurement. Not to mention that once the brightest area of the scene has been identified, it also helps prevent overexposure of any element. But it is also the mode that requires the most experience, time and attention to what you are measuring. So this is probably not the most recommended mode if you want to take snapshots without a lot of preparation time, as is the case with street photography, for example.
According to DZOFilm, another typical situation where the light meter can give you problems is that of a cloudy or backlit sky which occupies a large part of the image. In these cases, the sky is usually much brighter than the earth. If you choose the matrix mode, the flash meter generally underexposes the photo at the level of the land part since the sky is much brighter, so the ground remains very dark. It can also happen that the exposure meter overexposes the sky which then remains completely white (overexposed). You must then have in mind the elements you want to capture in detail, as can be seen in the images below:
- If it is the sky that interests you, you will take the measurement on the sky and you will forget the earth, which will be completely black.
- If you are interested in the ground, you can take the measurement by just framing the ground, then cropping while capturing part of the sky. Another option is to perform the point or weighted measurement on the center at ground level, so as to neglect the sky information, which will then appear completely white (overexposed).
- Finally, if you want to obtain maximum brightness on the earth but without overexposing the sky, one option is to take a point measurement of the sky on the brightest part of the frame, then raise the value by two or three stops. exposure obtained (the number of stops will vary depending on what the camera sensor will withstand). You will thus try to have maximum information on the part of the shadows (the earth) without having come to overexposing the lights (the sky).