How Digital Cameras Capture Images with Sensors, Shutters & Lenses

The Magic Behind the Click: How Digital Cameras Capture Images

Want to know how a click captures amazing photos? This article will explain how digital cameras work. You’ll learn about the different parts and how they capture a picture when you press the button. we’ll explore how parts like lenses, sensors, shutter, and aperture turn light into pictures.

By understanding these core components, you can know about digital cameras inside, and how digital cameras can work for taking images. It’s a general overview of camera insights. Not deep technical knowledge or deep mechanical knowledge.

This knowledge will help you to control the camera or will help you to know the deep knowledge about ISO, shutter speed, and aperture. 

Ok, let’s move.

• viewing System
• Sensor
• Shutter
• Aperture
• How Aperture Work
• Large Aperture
• Small Aperture
• Impact of Aperture on Light and Depth of Field
• Lens Elements
• Focusing
• Fill-up Mirror (DSLR Only)

Viewing System

There are two main viewing systems:

• Optical Viewfinder (SLR only): This uses a mirror (the reflex mirror) to reflect light coming through the lens (point no 1) upwards to a prism. The prism bends the light path (starting from pont no 1 then 2, 3 ,4, and 5) to the viewfinder, allowing you to see exactly what the lens captures.
• Electronic Viewfinder (EVF): This is a digital screen that displays the live image from the image sensor. It’s found in mirrorless cameras and on the back LCD screen of most cameras. But better view, an optical viewfinder is better for a photographer because the actual view can be made through the optical viewfinder.

Image Source: google

Sensor

The sensor is the heart of a modern camera which produces images from light. It’s an electronic chip covered in millions of tiny light-sensitive sites called photosites. When light hits these sites, they convert it into electrical signals. These signals are then processed to create a digital image. After clicking, this sensor within milliseconds produces the image and displays the image to the Electronic Viewfinder (EVF).

Shutter

The shutter acts like a curtain, controlling how long light hits the sensor. Now, how is this control achieved? The amount of light that reaches the sensor depends on how long the shutter remains open or closed.

The duration of light exposure on the sensor significantly impacts the image. For instance, if the shutter remains open for an extended period, more light will enter, resulting in a blurry image. Conversely, if the shutter is open for a shorter duration, less light will enter, producing a freezy image. This is particularly crucial for capturing moving subjects.

Aperture

The aperture is the opening in a camera lens that controls the amount of light that enters the camera.  It’s like the iris of the human eye. This amount of light, in turn, affects how much of the image will be in focus, which is known as the depth of field. The depth of field is an important factor in determining the overall aesthetic of a photograph.

How Aperture Work

Aperture can be thought of as the size of the opening in the lens.

Large Aperture

A large aperture means that the lens is opened wider, allowing more light to enter. However, a large aperture also results in a shallow “depth of field”, meaning that only a small portion of the image will be in sharp focus. This effect is often used in portrait photography to blur the background and draw attention to the subject.

Small Aperture

A small aperture, on the other hand, means that the lens is open more narrowly, allowing less light to enter. This results in a deep depth of field, meaning that a larger portion of the image will be in sharp focus. Small apertures are often used in landscape photography to capture sharp details throughout the scene.

Impact of Aperture on Light and Depth of Field

In summary, the aperture controls the amount of light that enters the camera and the “depth of field” of the image. Large apertures allow more light and create a shallow depth of field, while small apertures allow less light and create a deep depth of field.

Aperture is typically measured in f-stops, which is a standardized way of expressing the size of the aperture opening. A smaller f-number indicates a larger aperture, while a larger f-number indicates a smaller aperture.

If you want to know details about Depth of field, you have to read my another article about basic of Depth of field.

Lens Elements

The lens comprises multiple glass or plastic elements arranged in specific groups. These elements work together to focus light rays onto the sensor. By adjusting the distance between these elements, the camera achieves focus.

Focusing

Focusing means adjusting the lens elements to ensure the subject appears sharp in the final image. There are two main focusing methods:

• Autofocus (AF): The camera uses sensors within the body to analyze the incoming light and automatically adjust the lens elements for sharp focus.
• Manual Focus (MF): You rotate a ring on the lens barrel to adjust the focus distance yourself. This requires practice and a good understanding of focus indicators in the viewfinder.

Fill-up Mirror (DSLR Only)

Fill-up Mirror (DSLR only): This term is specific to Single-Lens Reflex (SLR) cameras. It’s another name for the reflex mirror mentioned earlier in the viewing system section. This mirror flips up temporarily when taking a picture, directing light to the image sensor instead of the viewfinder.

By working together, these components capture a single image. The viewing system lets you compose the shot, the sensor records the light information, the shutter controls light exposure, the aperture affects depth of field, and the lens elements with proper focusing ensure a sharp image.