When taking photos professionally, it is of great importance to control the exposure to obtain a successful photograph, since the environment can not always provide the lighting that we would like. For this reason, we must know the camera controls to compensate for light problems.
When it comes to photography, exposure is the term used to denote the amount of light the device’s sensor is exposed to. In this sense, the brighter the environment, the higher the level of exposure in the image, which means that the photographs are clearer.
When talking about exposure, it is important to take into account two other concepts, overexposure and underexposure. In the first case, an overexposed image is one in which we have captured too much light, which causes the photo to have very bright or completely white areas.
On the other hand, an underexposed photograph is one in which we have captured a very low level of light, which could cause images to be darker than we would like. Therefore, in most cases, the goal is to find a middle ground between both parameters to get a correctly exposed photo .
Also, it is possible to take overexposed or underexposed photos on a voluntary basis, depending on the artistic and conceptual intention of the photographer.
How to modify the exposure?
Most SLR cameras and other photo-taking devices have sensors that measure the brightness of the image. Today, many of these devices offer automatic modes to analyze the light in the center of the photo, the entire image or a specific area. However, if you want to take a more precise and professional photo, then you must know 3 basic parameters to adjust the exposure: the ISO, the aperture of the diaphragm and the shutter speed.
By carefully studying these three elements, we can understand that they are interconnected to completely control the exposure, so we cannot use just one, but the idea is to try to balance all three. This is what many photographers call the exposure triangle , because if we modify one of them, it is necessary to adapt the other two.
The ISO indicates the sensitivity of the sensor to light, so by increasing it the camera will capture more light, but this could lower the quality of the image.
As for the aperture of the diaphragm, it is the hole through which the light passes and can be increased or reduced according to the needs of the photographer. In this way, it is possible to change the exposure level without affecting the image quality. However, the exposure levels provided by the iris may be somewhat limited, and may not suit some lighting scenarios.
On the other hand, we must learn to modify the shutter speed, which can give us longer exposure times to capture more light , but at the same time it could generate blurred images, which is counterproductive when photographing people or moving objects.
When is it good to overexpose or underexpose a photograph?
The reality is that both dodging and underexposure can be very useful tools when taking a photograph. These terms are often used negatively to criticize a burnt photo or a very dark image. However, by correctly adjusting the exposure triangle, you can capture interesting photos, with some areas underexposed and others overexposed.
In this sense, we can take a good overexposed picture when we want to highlight the dark parts of an image, which can be very helpful, especially when taking pictures at night. However, it is important to know that the light areas turn white if the image is overexposed, which means that there is no information in these areas, only light. In this case, it is not possible to recover shapes or colors in post-production.
In an underexposed photo, the opposite happens to overexposure. By underexposing, dark areas could turn black, so the image has a lack of information in this part. Also, when trying to brighten a very underexposed image, we may create noise, which is just as serious.
However, the burn technique can be very useful in some cases, such as when we want to preserve the sky, since in most environments it has a lot of light, so it can look too white. Therefore, it is recommended to slightly underexpose the image to visualize both the sky and the scene correctly.
Also, underexposure and overexposure are useful for creating an effect called double exposure. In this case, you need to capture one underexposed and one overexposed photo. Next, we import the images into an editing program, layer them on top of each other, and add a filter for overlapping photos, resulting in a completely new image with a pretty cool effect. This method has been used in analog photography by exposing the same negative twice, which gave it the name of double exposure.
On the other hand, it is important to mention that the safest option to make overexposed and underexposed images that can be edited is to make them in RAW format , which provides a greater dynamic range, allowing the device to record a greater amount of information. both in the light and dark parts.
In short, many times we want to capture an image with a certain lighting level to create a specific atmosphere. However, shooting in auto mode is not always going to deliver the lighting results we need and this is where we need to put our knowledge of exposure correction to work. In this way, it is possible to use the manual settings of the camera to light a scene based on our creativity.