1.2.2. Camera Lenses

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• Unit 1 Quiz: 9/20
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• Self-Portrait Assignment:10/4
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• Unit 2 starts:10/16

Important Dates

1.2.1. Recap

• Viewfinders and LCD screens help compose and review images.
• Sensors are the heart of a camera and convert light into a digital image.
• Flashes illuminate the scene.
• Focus and zoom rings on the lens let the photographer change the focus and focal length.

Camera Lenses

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1.2.2.

Summary

1.2.2.

Learners can:

• discuss the design of the photographic lens
• recognize the historical and technological evolution from photographic manual lenses to automatic lenses

Vocabulary: aberration, camera lens, concave, convex, refraction, zoom ring

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Observe the two images of the same subject.

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An Introduction to Camera Lenses

The camera lens is one of the most important parts of a photographer's gear. If the camera is the brain, then the lens is the eye. A lens is a transparent piece of glass or plastic with at least one curved surface. It is an essential part of the camera that allows light to pass to the sensor to produce the final image. A lens works by refraction, the bending of light rays as they pass through a medium so they change direction. A camera lens is an optical device containing an assembly of different glass elements that bend light rays in specific ways to form an image of a scene on the image sensor of the camera. Each glass element inside the photographic lens works together in harmony to create a sharp image by focusing light onto the camera sensor. A good camera lens will capture sharp photos with plenty of details and contrast, while a poor lens can create images that look dull and blurry.

Camera Lenses

If the camera is the brain, then the lens is the eye.The lens is the detachable part of the digital camera that directs light to the digital sensor in order to produce the final image. It is an optical device on a camera. If you removed it and shot an image, your camera would create only images of white light.

Zoom is the ratio between the smallest and largest focal lengths in a digital photographic lens.Zoomed-in pictures can be produced by adjusting the optical feature of the zoom ring of the lens or cropping an image area during post-production.

Zoom

Focal length is the measurement of the optical distance between the point of convergence of the lens and the digital sensor. Focal length directly influences the angle of view and magnification. Focal length, usually represented in millimeters (mm), is determined when the lens is focused at infinity.

Focal Length

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The aperture value of the lens affects the depth of field (DOF). Depth of field describes how much of the image is in focus and how much of the image is blurred. It varies depending on the maximum aperture of the type of lens used. Two types of depth of fields can be achieved: shallow (achieved with a lower aperture number) and wide (achieved with a higher aperture number).

Depth of Field

Aperture is a hole or an opening in the photographic lens through which light enters into the camera to produce an image on the sensor. It affects the amount of exposure in an image and is measured in f-stops. If the f-number is smaller, then the opening of the lens aperture will be larger, allowing a larger amount of light to enter the camera.

Aperture

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Focus Ring

A focus ring is located on the camera body and is rotated to focus the image when in manual focus (MF) mode. When the autofocus function is enabled, the focus ring is moved by a small motor within the lens. Autofocus happens when the shutter release button is pressed halfway down. Autofocus mode does not require you to rotate the focus ring to adjust the focus.

Zoom Ring

A zoom ring is the part of the camera that allows you to change the focal length in real time. If you rotate the zoom ring, it will permit you to adjust the different focal lengths and fields of view (FOV) with the same lens.Essentially, it allows you to zoom in or zoom out on a subject. The numbers on the ring represent the current focal length of the lens in millimeters. Lenses are usually described by their focal lengths. For example, the focal length of 70-200 mm indicates that the lens can zoom anywhere from 70 mm to 200 mm.

A prime lens has a fixed focal length, which allows for sharper, higher-quality photos to be captured. Although prime lenses weigh less, they are less flexible due to their fixed focal length, so you cannot zoom in or zoom out. You will have to physically move your body in order to get wide shots or close-up shots with these lenses. Prime lenses are finely tuned to deliver specific types of photos, but you must know in which situations they can be used. For example, a 50 mm prime lens is perfect for portraits, whereas a 35 mm prime lens is usually used for landscapes.

Prime Lens

A zoom lens is one of the most common types of lenses and is extremely versatile. They have variable focal lengths because they contain a series of lenses inside. This makes them more flexible, offering you the capability of photographing anything, although not as quickly as with a prime lens. Zoom lenses are also bigger and heavier than prime lenses. For example, the popular 70-200 mm zoom lens can zoom from 70 mm to 200 mm.

Zoom lens

A wide-angle lens is used to capture a wider field of view. Wide-angle lenses have a focal length between 14 and 35 mm. Wide-angle lenses are generally used for landscape photography or street photography. They are able to capture a greater area in the frame, creating a much more vivid picture. These lenses are not good for achieving a shallow depth of field.

Wide-angle lens

Standard lenses offer an accurate representation of what the human eye sees in terms of both visual angle and perspective. Standard lenses have a mid-range focal length, usually between 35 mm and 85 mm. Most photographers use the popular 50 mm prime lens. Standard lenses can be used in various types of photography, as they capture images that appear more natural than those taken with other types of camera lenses. Standard lenses give the ability to capture both wide-angle and zoomed-in images.

Standard Lens

Lens Design

Convex lenses are thicker at the center and thinner at the ends. The convex lens is a converging lens that converges the light rays passing through it to a single point on the other side of the lens to form an image inside the camera. Convex lenses are used to focus on objects that are far away from the camera. Because the final image is produced by light passing through the lens to the opposite side, it is projected upside down.

🔥Convex Lens

Concave lenses are thinner at the center and thicker at the ends. These lenses have at least one surface that curves inwards.The concave lens is a diverging lens; it spreads out light rays that have been refracted through it. Concave lenses are used to focus on closer objects.

🔥Concave Lens

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The variations caused by optical lenses are referred to as lens aberrations. An aberration is an imperfection in the way a lens focuses the light it captures. They occur when the rays of light that pass through a lens fail to converge at a single point. Different aberrations can impact an image's sharpness, magnification, distortion, focus, or color. Early on, photographic lenses were designed using only convex-shaped glass elements to optimize image quality. Later, biconvex lenses were introduced to improve image quality and achieve a sharper image. However, biconvex lenses caused aberrations, which led to the technological evolution of photographic lenses. When light passes through a single biconvex lens, the focused image becomes slightly distorted, or blurred, in a phenomenon known as lens aberration. If a lens fails to focus all colors of light to the same convergence point, it is called chromatic aberration. Chromatic aberration can be corrected by combining convex and concave lenses to achieve a sharp image.

Lens Abberration

How Lenses Function

Video

Revisit the physics of how lenses work, and how refraction, spherical aberration, and chromatic aberration come about.

Interior Anatomy of Lens

Each glass lens is referred to as an element of the photographic lens, or lens element. There are many glass bodies that make up a lens. They help to achieve the desired outcome in the image. The number of lens elements varies inside the lens and depends on lens and lens type.

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Infrared Lens

Tilt-Shift Lens

Fisheye Lens

Macro Lens

Specialized Camera Lenses

Examples of photos with different lens

Interactive question

Summary

1.2.2.

In today's lesson, you learned that:

• lenses evolved from manual to automatic
• photographic lenses are designed by combining concave and convex lenses
• lens aberration is an imperfection in the way a lens focuses the light it captures, and photographic lenses evolved due to the need to correct these aberrations
• the exterior and interior parts of a lens work together to allow you to manipulate factors such as focus, zoom, and light and capture sharp photographs

In an upcoming lesson, you will learn about shutter speed.

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Questions?

Observe

The subject of both images is a man. He is seen standing in an office, leaning on a glass pane. The images were both taken from the same position.A very small section of the photograph is occupied by the subject, and he appears to be farther away from the camera. Other objects in the back, middle, and foreground can also be seen.

The lens used to distort perspective and make subjects appear smaller than their original size is called a tilt-shift lens. Tilt-shift lenses can be both tilted and shifted to manipulate the vanishing points of the scene. These lenses are used to reduce lens distortion, which improves image quality and provides sharp focus with excellent saturation and contrast. These lenses are most often used for architecture and fine art photography. Tilt-shift lenses are generally wide-angled, ranging from 17 mm to 35 mm.

Adam Gasson/PhotoPlus Magazine/Future. A tilt-shift lens. Digital Image. Retrieved 2022. Getty.

Tilt-Shift Lens

The infrared lens gives unique visual effects. They filter out other light waves and capture only the infrared light, whcih is practically impossible for the human eye to see. In contrast to other types of lenses, infrared lenses play with light rather than perspective. They are used to minimize focus shift issues, improving the focus and the overall quality of an image.

George Mdivanian / EyeEm. An infrared lens. Digital Image. Retrieved 2022. Getty.

Infrared Lens

An ultra-wide angle lens that can capture a 180-degree radius is called the fisheye lens. Fisheye lenses change the field of view of the image to make it look like a bubble. An ultra-wide-angle lens can have a focal length as low as 8mm. This lens is most widely used in abstract photography, indoors, or for design work, and allows for the capture of panoramic views.

Jesse Wild/N-Photo Magazine/Future. A fisheye lens. Digital Image. Retrieved 2022. Getty.

Fisheye Lens

Observe

In comparison, the image on the close up image, shows the man standing closer to the camera. A larger section of the photograph is covered by the subject. There are no other objects or distracting elements visible in the image.

Observe

• The environment is included with the greenery framing the subject.
• DOF is too shallow to focus on the subject.
• The chimpanzee is a little off-center, using the rule of thirds.

Observe

• Zoomed in close to the subject.
• DOF frames subject.
• Shallow focus area

• Details of the chimpanzee's face are crisp.
• The subject fills most of the photograph.

A macro lens is used to create extremely close-up, magnified, macro photographs. It produces sharp images when used at a very close range because of its unique design. Macro lenses are best for nature photography because they capture a lot of detail in a single image. They can magnify a subject up to five times its actual size.karimhesham. A macro lens. Digital Image. Retrieved 2022. Getty.

Macro Lens