1.8 Lenses and Sensors

1. Vibe Check

2. Lesson 1.8

3. Knowledge Check

Agenda

• match different types of digital camera lenses with their correct functions

• identify the characteristic features, types, and uses of camera lenses

• recognize the function of the focus ring and zoom ring

• identify factors affected by camera sensor size

  Vocabulary: angle of view, depth of field, field of view, focal distance, focal length, focal range, standard lens

Today, we can...

​***don't forget to download your guided notes as an extra resource

​Observe the differences in the photos....

​The subject appears to be further away from the camera and occupies a very small section of the photo is occupied by the subject. Objects in the entire scene including the background, middle-ground, and foreground (closest to the camera) are all in focus.

The image on the right shows the man standing closer to the camera. A larger section of the photograph is covered by the subject. The objects in the background are blurred so there are no distracting elements taking the focus away from the main subject.

​What do we notice?

Lenses

Lenses have been around for a long time and are used in many devices like telescopes, binoculars, glasses, and microscopes. They help people see things more clearly, whether by making distant objects look bigger in the case of telescopes or binoculars or by correcting vision like in glasses. One important type of lens is the photographic lens, which is used in cameras.

The lens helps manipulate light to form images. Without a lens, whether on a DSLR, mirrorless camera, or fixed-lens camera, the camera cannot focus light properly, which can result in an image that may only show white light.

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​The photographic lens is essential to all digital cameras because it directs light to the digital sensor to create the final image.

A good lens captures detailed and vibrant photos with sharp focus, while a poor lens can make images look dull and blurry.

​​Good lens

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DSLR and mirrorless cameras have interchangeable lenses that can be detached and replaced with different types of lenses.

Fixed-lens cameras, such as point-and-shoots and many smartphone cameras, have lenses that are built into the camera and cannot be removed.

***a bad lens can make images look dull and blurry ***

Essential Features of Digital Camera Lenses

Various characteristics determine how the camera lens will affect the appearance and quality of a photo. These characteristics are focal length, zoom, aperture, depth of field, angle of view, and field of view.

The angle of view refers to the area a lens can capture, while the field of view is how much of the scene is visible in the frame. These characteristics work together to shape the final image, affecting everything from composition to exposure and sharpness.

Focal Length

Zoom

​​Aperture

Depth of Field

Essential Features of Digital Camera Lenses

Focal length is the distance between where the lens focuses light and the camera’s sensor.

It helps decide how much of the scene you can see and how close things look in a photo.

• A longer focal length shows less of the scene but makes objects look bigger.

• A shorter focal length shows more of the scene but makes objects look smaller.

Focal length is measured in millimeters (mm) and is usually based on how the lens focuses on faraway objects.

Focal Length

🔥 Zoom on a camera lens means you can make things look closer (zoom in) or farther away (zoom out) without moving the camera.

This helps you take pictures of just one part of a scene or a bigger view of everything around it.

You can zoom by turning the zoom ring on the lens or by cropping the photo later on a computer. The zoom ring can only be used in manual focus mode.

Zoom

Aperture is an opening in the camera lens that lets light enter to create an image on the sensor.

Adjusting the aperture affects how bright or dark the image is and is measured in f-stops.

🔥 If the f-stop number is SMALLER, then the opening of the lens aperture will be LARGER, allowing MORE light to enter the camera.

🔥 If the f-number is LARGER, then the opening of the lens aperture will be SMALLER, allowing LESS light to enter the camera.

Aperture

The aperture (the opening in the lens) affects how much of the photo is in focus, which is called depth of field.

There are two types of depth of field:

• Shallow depth of field: Only a small part of the photo is clear (like the person or object you’re focusing on), and the background is blurry. This happens with a lower f-stop number (like f/2.8).

• Wide depth of field: Most of the photo is in focus, from front to back. This happens with a higher f-stop number (like f/11 or f/16), which is great for things like landscapes.

👉 A small f-stop number = more blur in the background
👉 A large f-stop number = more of the photo in focus

Depth of Field

Understanding key features of camera lenses, like focal length, makes taking photos in different settings easier.

Multiple Choice

What feature of a digital camera lens affects its angle of view and the level of magnification in photographs?

• aperture

• focal length

• depth of field

Key Parts of a Camera Lens

Various characteristics determine how the camera lens will affect the appearance and quality of a photo. These characteristics are focal length, zoom, aperture, depth of field, angle of view, and field of view.

The angle of view refers to the area a lens can capture, while the field of view is how much of the scene is visible in the frame. These characteristics work together to shape the final image, affecting everything from composition to exposure and sharpness.

​ Eight hotspots label parts of an interchangeable digital camera lens.

Parts of a Camera Lens

Parts of a Camera Lens

1. Filter Thread and Front Lens Cap

The filter thread is where you screw on and fasten your filters and lens cap.

The front lens cap protects your lens and filter from dust and scratches. It should always be mounted when you are not using the lens to avoid any damage.

Parts of a Camera Lens

2. Lens Hood Mount

The lens hood can be mounted to protect the lens from stray light, accidental bumps, and dirt that may get in your way when you are shooting.

Parts of a Camera Lens

3. Focus Ring

The focus ring is used to adjust the focus when you are shooting in manual mode.

Parts of a Camera Lens

5. Zoom Index

The white marker line, displayed to the left of 18, is the zoom index that tells you the current focal length.

Parts of a Camera Lens

4. Zoom Ring

You can adjust the focal range by zooming in or out with the zoom ring. The focal range is the distance a lens can cover, allowing you to take wide and close-up shots. A Canon EF-S camera lens has a focal range of 18-135mm, which means it can zoom in between 18 to 135 mm.

Parts of a Camera Lens

6. Lens Specification Marking

The lens in the image is the Canon EF-S 18-135mm IS kit lens. The "18-135mm" refers to the distance between the lens and the sensor, meaning how much you can zoom in and out. The "IS" indicates it has image stabilization, which helps reduce blur.

"EF-S" means this lens is designed for specific crop sensor camera models. Crop sensors are smaller in size and are used to crop subjects to make them look larger. Lens specifications can vary from one lens to another.

Parts of a Camera Lens

7. Autofocus: Manual Focus and Image Stabilizer Switch

This switch button allows you to choose between:

AF - autofocus (all focusing is done by pressing the shutter button halfway)

M - manual focus (focusing can be done manually by turning the focus ring)

The IS switch allows you to switch on the image stabilization feature of the lens to prevent image blur.

Parts of a Camera Lens

8. Lens Mount and Rear Lens Cap

The lens mount has points that connect with the camera. A rear lens cap is essential when the lens is not attached to the camera to protect these points from moisture and dust.

Multiple Choice

Which part of the digital camera lens is used to adjust the focus when shooting in manual focus mode?

• focus ring

• filter thread

• lens mount

Adjusting focus is crucial for capturing sharp images.

Move on to explore more about the zoom ring and focus ring, which help you change the composition and framing of your shot. Understanding these tools will improve your ability to capture the perfect photo.

Focus Rings and Zoom Rings

Interchangeable digital camera lenses have focus rings and zoom rings. The rings help you frame a scene, focus the image, and highlight a specific subject.

Focus Rings and Zoom Rings

🔍 Focus Ring – Helping Your Camera See Clearly

The focus ring is a part of the camera lens that you can turn with your hand to make the picture look clear.

You use it when the camera is in manual focus mode, which means you choose what part of the picture should be sharp.

​Focus Ring

Focus Rings and Zoom Rings

• When you turn the focus ring, you can pick what object or area you want to be in focus.

• Sometimes, you’ll see numbers on the lens that show how far away the object is.

If the camera is in autofocus mode, it does the focusing by itself, so you don’t need to use the focus ring.

​Focus Ring

Focus Rings and Zoom Rings

🔍 Zoom Ring – Making Things Look Closer or Farther

The zoom ring is a part of the camera lens that you can turn to make things look closer (zoom in) or farther away (zoom out) in your photo.

​Zoom Ring

Focus Rings and Zoom Rings

• Turning the zoom ring helps you choose how much of the scene you want to see.

• Some lenses can zoom a lot, and others can’t zoom at all—they stay the same.

📏 The numbers on the lens (like 70–200 mm) show how much the lens can zoom.

A lens like that can zoom from 70 mm (less zoom) to 200 mm (more zoom).

​Zoom Ring

Labelling

Which part of the lens is the zoom ring? focus ring?

Drag labels to their correct position on the image

focus ring

zoom ring

Camera Lens Types

Prime lenses and zoom lenses are the two most popular types of camera lenses.

Prime lenses have a fixed focal length, meaning they do not zoom. They often produce sharper images and perform better in low light.

Using a prime lens requires photographers to move closer to or farther away from their subject to get the right shot.

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Prime Lens

Zoom lenses provide a variety of focal lengths, allowing photographers to adjust the zoom level without having to switch lenses or physically moving closer or further away from the subject.

It is important to note that zoom lenses are generally larger and heavier than prime lenses, such as the popular 70−200 mm zoom lens pictured right, which can zoom from 70 mm to 200 mm.

Zoom Lens

Zoom lenses let you change the focal length, allowing you to adjust how close or far away subjects appear in your photos.

Longer focal lengths enable you to capture distant subjects while making them look closer. This feature is helpful for photographing wildlife or sports events where getting physically close is not possible.

Zoom Lens

Camera Lenses Based on Focal Length

Both prime and zoom lenses come in different types based on their focal length. The focal length of a lens affects how much of the scene you can capture and how close or far objects appear in your photos. Different focal lengths can make your subject look closer or farther away and change your image's overall look.

Camera Lenses Based on Focal Length

🔭 Telephoto Lenses – Seeing Things Far Away

Telephoto lenses are special camera lenses that help you take pictures of things that are far away, like wildlife (animals) or sports players.

• They can zoom in a lot, just like a telescope!

• Some telephoto lenses can zoom from 70 mm to 200 mm or even more.

Camera Lenses Based on Focal Length

These lenses are great for wildlife and sports photography, but they can be:

• Big and heavy

• Expensive

• Hard to hold steady, so photographers often use a tripod to keep the camera still.

Camera Lenses Based on Focal Length

🌄 Wide-Angle Lenses – Seeing More in One Picture

Wide-angle lenses help you take pictures of big scenes, like mountains, buildings, or large groups of people.

They let you fit more into one photo than other lenses.

But wide-angle lenses usually keep everything in focus, so it’s hard to make just one part of the picture stand out while the background is blurry.

Camera Lenses Based on Focal Length

👀 Standard Lenses – What Your Eyes See

Standard lenses take pictures that look natural, kind of like how your eyes see the world.

They show the scene at a normal size—not too zoomed in and not too wide.

These lenses usually have numbers like 35 mm to 85 mm. A common one is 50 mm, which is great for everyday photos.

Camera Lenses Based on Focal Length

Standard lenses are good for taking pictures of people, places, and things without making them look stretched or squished.

Match

Match the digital camera lens with the correct name.

standard lens

wide-angle lens

telephoto lens

• standard lens

• wide-angle lens

• telephoto lens

Camera Sensor

The camera sensor is the most essential part of the camera because it is where the image is formed. It captures the light that enters through the lens and turns it into a digital picture. Without the sensor, the camera would not be able to create images.

In the focal length video, you learned how camera sensors come in different sizes, and these sizes affect the quality and appearance of your photos.

Digital camera sensors are made up of photosites, which are light-sensitive elements that capture light and convert the light into a photo.

Larger sensors have more photosites, capture more light and detail, producing clearer images, especially in low light.

Smaller sensors, like those in smartphones, have fewer photosites. They are convenient but may not capture as much detail. Each type of sensor affects how photos look, including details, colors, and performance in various lighting conditions.

Camera Sensor

Digital Camera Sensor Sizes and Types

Photosites – Tiny Light Catchers

Inside a digital camera, there's a special part called the sensor that collects light to make a photo.

Instead of using film like old cameras, the sensor uses millions of tiny spots called photosites.

• Each photosite catches light and turns it into a pixel—the small dots that make up a digital image.

• Every pixel is made from three photosites: one for red, one for green, and one for blue. These colors mix together to create the full-color photo you see.

Digital Camera Sensor Sizes and Types

The camera megapixel count shows how many of these photosites a camera sensor has. For example, a 24-megapixel camera has 24 million photosites.

Look at the image below to the left to see how photosites capture color images.

Digital Camera Sensor Sizes and Types

📷 Camera Sensor Sizes and Types

The size of a camera’s sensor affects how much light it can use to make a photo.

A larger sensor collects more light, which helps create clearer pictures with better detail, especially in low light.

• Bigger sensors also show more of the scene.

• A smaller sensor might crop part of the image and can make photos look grainy or less detailed.

Digital Camera Sensor Sizes and Types

Full-Frame Sensors: These sensors are the same size as a 35 mm film frame (about 36 mm x 24 mm) and provide excellent image quality, depth of field, and low-light performance.

Digital Camera Sensor Sizes and Types

APS-C Sensors: Slightly smaller than full-frame sensors (about 23 mm x 15 mm), APS-C sensors are common in many digital cameras and offer a good balance of image quality and size.

Digital Camera Sensor Sizes and Types

Micro Four Thirds Sensors: These sensors are smaller (about 17 mm x 13 mm) and are used in some mirrorless cameras. They allow for smaller and lighter camera bodies but may not perform as well in low light as larger sensors

Digital Camera Sensor Sizes and Types

1-inch Sensors: These are compact sensors (about 13.2 mm x 8.8 mm) often found in high-quality small cameras. They provide good image quality in a small package.

Digital Camera Sensor Sizes and Types

Point-and-Shoot Sensors: These are typically smaller sensors in smaller cameras, like smartphones and point-and-shoot cameras. They are designed for easy use, are lightweight, and are easy to carry, but they may produce lower-quality images than larger sensors

Digital Camera Sensor Sizes and Types

​The size of a camera's sensor affects the image quality and resolution, depth of field, and angle of view in each photograph.

Digital Camera Sensor Sizes and Types

Digital photo resolution is about how clear and detailed a photo looks on a screen or when printed.

Imagine a photo is made up of tiny dots called pixels. The more pixels a photo has, the more detail it can show. It’s like building a picture with LEGO blocks—the more blocks you use, the better the picture looks!

Digital Camera Sensor Sizes and Types

🖼️ Why Does It Matter?

High resolution = sharp, clear images (great for printing or zooming in).

Low resolution = blurry or pixelated images (not great for printing).

Digital Camera Sensor Sizes and Types

Depth of Field (DoF)

Smaller sensors require a wide-angle lens or more distance from the subject in order to create a shallow depth of field. The large sensor blurs the background to make the subject of the image pop.

Smaller sensors create a deeper depth of field due to their shorter focal lengths.

Digital Camera Sensor Sizes and Types

Angle of View

The angle of view is the visible frame of the scene captured by the image sensor.

Small sensors have a cropping effect.
Wide-angle views capture greater areas, while small angles capture smaller areas.

Digital Camera Sensor Sizes and Types

🔥 Depth of field is how much of your photo is in focus, from front to back. 🔥 The aperture controls the depth of field.

A shallow depth of field created by a wide aperture (like f/2.8) creates a blurred background with only the subject in focus. A shallow depth of field is great for making your subject stand out.

A deep depth of field created by a narrow aperture (like f/22) keeps everything in focus, which is good for landscapes.

Multiple Select

Which factors of an image are affected by camera sensor size? Select 2 that apply.

• image quality and resolution

• creativity

• depth of field

How Sensors and Lenses Control the Look of Your Photos

• Smartphone cameras have small sensors but still take good pictures thanks to advanced technology. They come with fixed lenses, making them user-friendly.

• Point-and-shoot cameras have larger sensors and zoom lenses but lack some features found in DSLRs.

• DSLRs and mirrorless have the biggest sensors and interchangeable lenses, providing better control and image quality, although they can be heavier and more complex to use.

Today we learned...

• there are different types of camera sensors that come in different sizes; and

• different types of camera lenses are used for a variety of reasons.

Knowledge
Check...

Dropdown

Match each function with the name of the correct lens part. ​

Select answer

allows you to change the focal length. ​

Select answer

allows you to adjust the camera to capture a sharp image.

Match

Match each type of digital camera lens with its function description.

captures a wider field of view, making

captures wide field of view

ideal for capturing distant subject

• captures a wider field of view, making

• captures wide field of view

• ideal for capturing distant subject

Labelling

Which part of the lens is the zoom ring? focus ring?

Drag labels to their correct position on the image

zoom ring

focus ring

Open Ended

What is your favorite type of presentation? (could be from other teachers as well...) Examples: wayground, genialy, powerpoint, google slides, others...)