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How does light travel through a DSLR camera

A Digital Single Lens Reflex camera is a powerful piece of photography kit. It combines one lens, letting the photographer control focus and zoom. Plus, digital technology captures shots on a digital medium.

Wanna know more? Let’s explore how light travels through a DSLR camera and what it does to images!

What is a DSLR Camera?

A DSLR Camera is a digital type that fuses optics and mechanisms of a single-lens reflex camera plus a digital imaging sensor. It differs from other digital cameras by the reflex design scheme.

Light enters the camera thru the lens, then reflects off a mirror to the optical viewfinder before reaching the image sensor. This allows real-time viewing, without having to wait for the sensitivity of photo paper to develop.

Interchangeable lenses with varying focal lengths capture different shot angles and field depths, offering more control than point-and-shoot cameras. You can shoot in manual or program mode, which automates shutter speed & aperture settings.

Image sensors are either CCD or CMOS. Processors transform the data from the image sensor into photo files, like JPEGs. Stabilization systems can be built-in on camera bodies or lenses, to minimize camera shake from hand movements for sharper images.

Understanding the DSLR Camera Parts

A DSLR camera is a digital device which combines the optics and mechanisms of a single-lens reflex camera with a digital imaging sensor. It’s used to capture images or take photos.

We’re going to learn more about the parts of a DSLR camera. That way, we can get a better understanding of how light travels through it.


The lens is one of the most important parts of a DSLR camera. It is an interchangeable glassway, like the old 35mm film camera lenses. It has a metal housing, plus many glass elements, and a focusing group.

The front of the lens has a big opening for light gathering and protective elements to keep out dust and moisture. Inside, it has many elements that create the image seen on the image sensor.

Sometimes, multiple glass elements are held in a single ring or thread – this is called an “element group”. Some lenses may have extra parts like microscrews and small motors to control zooming and focus.

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The two main areas of a DSLR camera lens are the aperture (f-stop) and focal length (mm). The f-stop decides how much light goes through the lens at different exposure settings, and the focal length decides how close or far away objects appear in the image. Knowing these components helps you pick the right lens for your photography.


A DSLR camera has a primary component, the mirror. It directs light from the lens to the reflex viewfinder that reflects the scene upside down and backwards. The reflex mirror is placed in front of the focusing screen, at an angle.

When the shutter button is pressed, the mirror swings away. This allows light to reach the image sensor. To stop additional light, two curtains close very quickly and almost silently.

A small electric motor controls the open/close mechanism of the curtains. Another motor controls the speed of the mirror when taking photos. The back of the mirror is coated with microcrystals which reflect in a specific direction. This gives natural contrast, so you can take perfect images without any manipulation.


The shutter is a vital part of a DSLR camera. Press the button on the top, and the shutter opens to let in light. This light is stored on a digital memory card. The amount of time the shutter stays open is called ‘shutter speed’. It ranges from fractions of seconds to longer times, depending on the image.

Shutter speeds below 1/250th need stabilization, like a tripod or flash. This prevents objects in motion from blurring together. Also, faster shutter speeds are ideal in sports or wildlife photography and help in dark environments with low light.

When using slower shutter speeds, like for blurring people walking by, use a tripod and other stabilization. This keeps the subject sharp, while other elements stay blurry.


The sensor is located at the back of the camera. It’s a sophisticated part of a DSLR camera. It converts incoming light into electrons. This creates an image. It’s also known as the ‘image-capture’ or ‘receptor’ element. The quality of this image depends largely on the sensor’s quality.

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The modern DSLR sensor consists of two parts. These are extensions and pins. Light shining on them is converted into electrical signals. These signals are fed into an internal processor. That produces a digitized image or photograph.

Extensions are made up of millions of photosensitive sites. These recognize straight, curved or diagonal lines. Each dot captures one pixel at a time. That’s why they’re called ‘photodiodes’. About 30 million photodiodes make up today’s DSLR sensors. They vary in color sensitivity and sensitivity to UV and IR radiation. That’s how visual information is converted into digital data.

We can see how extensions work by looking at two separate photos taken from different angles. In the first photo, the object appears small due to the proximity of the lens. But if a photo is taken from further away, the object looks bigger. That’s because it’s further away from the physical lens.

Inside your sensor, light approaches each Extension group. The distances between points are measured. This generates an image. It’s fed through processor circuits. That allows details in highlights/shadows and colors to be reproduced faithfully onto photographs. That’s how we get sharp images.

How Does Light Travel Through a DSLR Camera?

Photographers often ask me, “How does light move through a DSLR camera?” It’s a great question for new photographers to learn about photography basics. Here’s an article to help you understand it.

Light travels via a DSLR camera. We’ll look at the components used to take photos.

Light Enters Through the Lens

Light enters the camera lens and is sent to the mirror assembly. This lets the user see what will be seen in the image before taking the photo. There is a secondary mirror inside the system called the micro-servo mirror. It rotates and can be adjusted.

Autofocus cameras use a sensor to detect and focus on certain objects or subjects in the frame automatically. Then, light passes the point and reaches the shutter mechanism. This is located between the back of the lens and the sensor that stores or records light digitally or onto film.

The diaphragm is controlled by blades. These control how wide or narrow the exposure time is. This means how long each droplet of light hits the individual pixel or point of film. The amount of time each pixel is exposed affects its brightness value, creating images with highlights and shadows.

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This is called dynamic range or tonal scale range. Such elements as rasterized images and video frames have this. The iris/diaphragm clicks into different settings based on chosen F-stop or Focal Ratio numbers, such as 1:1, 2:1, 4:1, 8:1, etc.

Light is Reflected by the Mirror

When the shutter button is pressed on a DSLR Camera, a tiny mirror located at the back within the pentaprism flips up. This allows light from outside to enter, which is then focussed onto an image sensor within a fraction of a second.

In film cameras, light first passes through the lens and onto an exposed film before printing. However, in DSLR cameras, light goes directly to the image sensor to be captured as a digital photograph.

The position of mirrors and other components used in this process may differ slightly for different camera makes and models. But overall, it is the same for most DSLR cameras.

Light is Captured by the Sensor

A DSLR camera has a lens at the front which lets light pass through and reach the sensor. This light is an electromagnetic wave with different colors having different wavelengths. The lens focuses all these colors on a single point of the sensor.

Unlike traditional film cameras, there are no mirrors inside a DSLR camera which allows uninterrupted light travel. This brings out more detail and clarity from each shot. Then, the electromagnetic wave is broken down into particles, or photons. Each photon strikes an individual pixel which records it digitally.

These pixels can record different colors depending on their size and shape. This work of lenses and sensor capture light entering from outside and record them digitally so we can view them on computers or phones.


Understanding how light travels through a DSLR camera is a fascinating journey that sheds light on the inner workings of this incredible piece of technology. From the moment light enters the lens to the final image captured on the sensor, a complex interplay of optical and electronic components work together to create the stunning photographs we love.

As photographers, appreciating the science behind our cameras helps us make more informed decisions about our gear, settings, and techniques. So, let the knowledge of light’s incredible journey through your DSLR camera inspire you, and continue capturing the world in all its beauty, one perfectly exposed moment at a time.

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