Understanding Exposure in Photography

Exposure is one of the key elements that will determine what is stored in the sensor of a camera or photographic film. You need to understand this term in photography to get the best shots as possible with your camera. At the beginning of learning photography, nothing may be as important as exposure. The more time you spend studying and practicing technical features, the faster you will progress in the artistic dimension of photography.

Exposure in photography is the light that hits the sensor ,there are three adjustable elements to control that on photography that are ISO (International Standards Organization), aperture and shutter speed that defined below;

Understanding Exposure in Photography

1. ISO rate determines the sensitivity of the sensor to light, and increasing each step of the ISO numbers (up or down) indicates a doubling or halving of the sensor’s sensitivity to light and will affect exposure.

ISO rates ranging from 25 to 3200 (and even higher) indicate light sensitivity. The lower the number, the less sensitive the image sensor is to light. The higher the ISO number (and the higher the sensitivity), the more powerful the image sensor works to capture an effective image, resulting in more digital noise. Digital camera engineers have designed image sensors to perform well at low ISOs (such as video), which is the ISO value of most digital cameras, although some professional digital cameras have ISO 50 or even 25.

 

What is digital noise?

Any light signal that is not emitted from the subject and as a result, creates a random color on the image.

 

1. Aperture is a technical and artistic tool for you as a photographer. By deciding, what lens you want to shoot with, or what f-stop you prefer, and how far away you want to be from the subject and by that you will control the EX and depth of field of the photo. In other words, is the amount of focused light passing through the lens. At a small f-stop, for example, f / 2, a huge amount of light will enter the lens, and this will happen even in a fraction of a second; But at f / 22, the aperture is probably at its smallest, and a small amount of light will enter the lens. It is interesting to know that in quality zoom lenses, the focal length of the lens will not matter as long as the f-number is constant. The reason for this is the mathematical equations for F-number, which, if the number F is constant, will provide a constant light transmittance for 35mm and 100mm lenses with a shutter speed of for instance 1/125 of a second.

 

1. Shutter speed is a mechanical screen in front of the sensor that determines how long light is shining on the sensor. The slower the shutter speed, the longer the exposure time and the lighter shines on the sensor. The result is a clearer picture. For example, a speed of 1.4000 seconds is high speed at which a short moment of light shines on the sensor. At high shutter speeds, you can capture sharp images of moving objects and freeze for a moment, By other words, it determines the speed at which the aperture opens and closes. Each number on this scale will also indicate a certain amount of light entering or preventing light from entering and this also plays an important role in photography exposure.

• Any change in these three elements will have a definite and measurable effect on the reaction of the other two elements and consequently on the film frame or photosensor and how the final image will look or by other words affect exposure photography. For example, by increasing the number F (smalling the aperture), the amount of light entering the image sensor will decrease, but the Depth of field (DOF) will also increase simultaneously in the final image. Slowing down the shutter speed affects how motion is recorded, which may blur the background or subject slightly. Reducing the shutter speed (keeping the shutter open for longer) will increase the amount of light entering the sensor; The result is a clearer picture. Increasing the ISO will allow you to shoot in darker areas, but on the other hand, it will increase the digital noise in the photo, that’s why these three elements are quite crucial on photography exposure.

Exposure compensation

 

You need to know that exposure compensation allows you to tilt your camera’s exposure towards overexposure or underexposure. That is displayed with a + and – sign. Positive numbers can be set for more exposure and negative numbers can be set for lower exposure.

Exposure compensation often misleads a camera into providing poor exposure. Keep in mind that if your situation changes, this option may no longer be accurate, so always remember to reset it when your work is done by exposure compensation, otherwise your photos might be affected with bad quality.

exposure triangle chart

ANOTHER :

Bracketing in photography

Bracketing is a method in which several shots of the same scene are taken with different exposure settings. By doing this, you can be sure that one of the photos has the most appropriate exposure. Also, Auto Exposure Bracketing usually results in a standard photo, a photo with insufficient exposure, and a photo with overexposure. By giving you three images (or five, or seven, depending on what your camera allows and how you adjust it), your chances of getting the most exposure image increase.

Manual exposure mode

This mode allows you to change the aperture and shutter speed independently of each other. Although the camera still uses the metering pattern you have chosen for EX, and you must adjust each parameter yourself. Manual exposure mode can take more time, but gives you more control and allows you to easily make adjustments.

 

Center-weighted metering Vs. spot metering 

 

Center-weighted metering tends to expose the exposure to the main subject but also the surrounding areas, while the spot metering option only covers a very small proportion of the scene in photography exposure. Spot metering is useful when the subject occupies only a small proportion of the frame, such as recording an insect on a grass. This option ensures that the EX for the subject is quite accurate.

NOTE : in this article EX means exposure.