Camera lens

A camera lens is a special group of lenses used with cameras to create images of objects. These images can be recorded on photographic film or on electronic devices like digital cameras. The lens works together with the camera body to capture clear and detailed pictures.

Different kinds of camera lenses, including wide angle, telephoto and speciality

Lenses can be used for many types of devices, such as still cameras, video cameras, telescopes, and microscopes. Some cameras have a fixed lens, while others allow you to change the lens to get different effects, like changing the distance or how much light the camera uses.

Even though a simple lens can create an image, most camera lenses are made from many pieces to reduce problems that can make pictures blurry. The people who design these lenses try to balance these issues to make the best possible pictures for everyday use.

Theory of operation

A simple way to think about camera lenses is by comparing them to pinhole lenses. A pinhole lens is just a tiny hole that lets in light to form an image. But pinhole lenses have some big problems: they can be blurry, let in too little light, or get blurry again if the hole is made too small.

Real camera lenses solve these problems. By adding a curved lens right at the pinhole, more light can be let in while keeping the image sharp. This lens bends the light so that rays from each point on the object meet at the same spot on the camera sensor or film. Even with more complex lenses made of many pieces, the basic idea stays the same: gather light at one point and focus it to a sharp spot on the image plane.

Construction

Main articles: Photographic lens design and History of photographic lens design

A camera lens can be made from just one piece, like in the old Box Brownie, or from over 20 pieces in more complex lenses. These pieces can be grouped together and stuck with special glue.

The zoom lens assembly of the Canon Elph

The front piece of the lens is very important. Modern lenses have a special coating to help them stay clean and work better. The way the lens is curved helps it focus light properly.

Lenses are usually made of glass because it looks clear and doesn’t scratch easily. But sometimes other materials like special glass, plastic, or even unusual substances are used. Plastic can make lenses with special curves that are hard to make with glass.

Lenses can be focused by moving parts of the lens closer or farther from the camera. Some lenses have special systems to help them focus better.

Most lenses today have many layers of coating to keep unwanted light out. Some also have a special coating to block a type of light that can change colors. Lenses also usually have a way to control how much light gets in, like a tiny shutter or a moving plate with different-sized holes.

Aperture and focal length

Apertures in 1-stop increments on the same lens.

Two main features of a camera lens are its focal length and its maximum aperture. The focal length decides how big the image will be and how much of the scene you can see. A shorter focal length shows more of the scene, while a longer one zooms in closer.

The aperture controls how much light reaches the camera sensor. A wider aperture, with a smaller number, lets in more light, letting you take pictures faster. It also makes the background appear softer. Lenses can be normal, wide-angle, or long-focus, depending on their focal length. Each type changes how you see the world and how far away you need to be from your subject.

Number of elements

Main article: Photographic lens design

The number of parts in a camera lens depends on how wide the view is, how big the opening is, and how much the lens costs. Some lenses need many parts to work well, especially wide-angle lenses with big openings. Other lenses, like long, narrow ones, can work with just a couple of parts.

Older cameras sometimes had special lenses that could change. You could unscrew part of the lens to get a narrower view. Modern lenses have special coatings to make pictures clearer and brighter, especially when the lens changes its zoom. Even with many parts, today’s lenses still give great pictures.

Lens mounts

Main article: Lens mount

Many single-lens reflex cameras and some rangefinder cameras can have lenses that you can change. Some other types of cameras, like the Mamiya TLR cameras and SLR, also let you switch lenses. Companies like Bronica, Hasselblad, and Fuji make cameras that let you change lenses too, and mirrorless interchangeable-lens cameras do this as well. These lenses connect to the camera using something called a lens mount. This mount has parts that help the lens and camera work together.

The way the lens mount is made is very important because it decides which lenses can fit on which cameras. There isn’t one rule for all camera makers, so each big company usually makes its own style of mount that only works with their cameras. Some older styles, like the Leica M39 lens mount for rangefinders, M42 lens mount for early SLRs, and the Pentax K mount, were used by many brands, but this isn’t common now. A few mount styles, like the Olympus/Kodak Four Thirds System mount, have been shared with other makers. Big cameras often let you change lenses too, usually by putting them on a special board or holder.

Today, the most common mounts you’ll find include the Canon EF, EF-S and EF-M mounts, the Nikon Z-mount, older Nikon F-mount, the Olympus/Kodak Four Thirds and Olympus/Panasonic Micro Four Thirds mounts, the Pentax K mount and its newer versions, the Sony Alpha mount (which comes from the Minolta mount), and the Sony E mount.

Types of lenses

A macro lens is used for taking very close pictures of small objects. It can capture images that are the same size as the object or even larger. These lenses can be used at different distances and may need special tools to work well for very close shots.

Zoom lenses change their focal length, meaning they can zoom in and out. This is done by moving parts inside the lens, often by turning a knob or pressing a button. Zoom lenses are popular for many types of cameras because they are flexible and easy to use.

History and technical development

Further information: History of photographic lens design

A camera lens is a special group of lenses used with cameras to create images, either on film or digital media. These lenses can be built into the camera or changed to different types with various properties, like how far they can focus or how wide the view is. The basic idea behind a camera lens is the same as in other tools like telescopes or microscopes, but each has its own unique design.