Tiempo de exposición

What is exposure time in photography?

Exposure time is a key concept in photography, as it determines the amount of light reaching the camera sensor, affecting the illumination and sharpness of an image. It is measured in seconds or fractions of a second and is adjusted by the shutter. In simpler terms, the shutter is the device that controls how long the camera sensor will be exposed to light. Knowing and properly managing the exposure time will allow you to improve your photographic skills, capturing images with the desired lighting and motion effect.

How does a camera shutter work?

To understand exposure time in depth, we must first explore how the shutter works. There are two main types of shutters:

• Focal plane shutter: located just in front of the focal plane, it is constructed with two shutters. When the shutter release button is pressed, the first shutter curtain moves, allowing the sensor to be exposed to light. After the selected exposure time, the second shutter curtain closes to end the process.

• Central shutter: Common in large and medium format cameras, it is located on the photographic lens. It works radially allowing light to pass through the metal lamellae onto larger photographic surfaces.

What is the role of SLR and mirrorless cameras?

SLR cameras, also known as SLR (for analog) or DSLR (for digital), have a specific mechanism involving a mirror and a pentaprism. This system allows the photographer to see a preview of the image through the viewfinder. However, when the shutter release button is pressed, the mirror is raised allowing the light to fall directly on the sensor.

Mirrorless cameras, on the other hand, do not have this mirror device. Instead, they use a processor to correct and display the image directly and correctly, facilitating a more compact design.

How is exposure time measured?

Exposure time is measured in seconds or fractions of a second. For example:

• 2": two full seconds.
• 1/2: half a second.
• 1/4: a quarter of a second.
• 1/8: one eighth of a second.

These values are standardized in the world of photography and are considered full exposure steps.

What are the effects of a long or short exposure time?

Exposure time impacts both the lighting and the aesthetics of the image:

• Long exposure: Allows for more light to enter, ideal for capturing motion in images, such as animals running. However, it also requires the use of a tripod or stand to avoid blur due to unwanted movement.

• Short exposure: Limits the entry of light, "freezing" motion in fast images. For this, a stand is not necessary as the time is short enough to avoid blur.

Knowledge and manipulation of exposure time is essential to create creative effects such as astrophotography or silk effects in landscapes. These techniques will be explored more in depth in future classes, promising to enrich your ability to capture stunning images.

Dare to experiment with your camera and exposure times to discover new creative possibilities in your photography!