Camera lens

A camera lens is a group of lenses used with cameras to make pictures of objects. These pictures can be saved on photographic film or on digital cameras. The lens works with the camera to take clear and detailed photos.

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

Lenses are used for many devices, like still cameras, video cameras, telescopes, and microscopes. Some cameras have one fixed lens, while others let you change the lens to get different effects, such as changing the distance or light.

Simple lenses can make an image, but most camera lenses have many pieces to help make the pictures clearer. The people who design these lenses work to balance problems so the pictures look their best for everyday use.

Theory of operation

You can think about camera lenses like pinhole lenses. A pinhole lens is a tiny hole that lets light in to make an image. But pinhole lenses have some problems: they can be blurry, let in too little light, or get blurry if the hole is too small.

Real camera lenses fix these problems. By adding a curved lens at the pinhole, more light can come in while the image stays 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 is 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 many 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 parts of a camera lens are its focal length and its maximum aperture. The focal length decides how big the picture 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, so you can take pictures faster. It also makes the background look 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 what you are taking a picture of.

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 let you change the lenses. Other cameras, like the Mamiya TLR cameras, also let you switch lenses. Companies like Bronica, Hasselblad, and Fuji make cameras that let you change lenses, and mirrorless interchangeable-lens cameras do this too. These lenses connect to the camera using something called a lens mount. This mount helps 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. 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 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 close pictures of small objects. It can make images the same size as the object or even bigger. These lenses work from different distances and sometimes need special tools for very close shots.

Zoom lenses change their focal length, so 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 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 group of lenses used with cameras to make pictures. You can use these lenses on film or digital cameras. The lenses can be part of the camera or you can change them to different types. These different types can change how far the camera can focus or how wide the view is. The idea behind a camera lens is similar to tools like telescopes or microscopes, but each one has its own special design.