Camera Lenses Explained (A to Z): All You Need to Know About Camera Lenses

  • Lenses
  • 23 min read
Camera Lenses Explained

In this article, I will try to cover all about camera lenses for beginners. I explained camera lenses from A to Z, and after reading this post you’ll be able to select the best lenses for your camera without any hassle. So let’s get started.

What is A Camera Lens?

First of all, it is the soul of the camera. This soul consists of several lenses located in the body (also called the frame). The objective of the lens is to project the picture of the real world to the surface of the camera matrix or film. When pressing the button, the lens transmits light and draws an image of the required size on the matrix.

Camera lenses are known to be characterized by focal length and aperture ratio. Lenses can have many characteristics: bayonet, lens coating, resolution, automatic (or manual) focusing. They can transmit data to the camera and can have dust and moisture protection or not.

Camera Lenses Explained from A to Z
Camera Lenses Explained from A to Z

Many modern lenses are equipped with automation, many are packed with electronics, various micromotors, and an image stabilizer is also built into Canon and Nikon lenses.

In addition, lenses can be permanently built into the camera (as in compacts). They can be in the form of a separate device placed on a camera with interchangeable lenses (for example, an SLR camera.) Such lenses expand your photography capabilities almost unlimitedly, and to the same extent, they empty the wallet. 😜😜😜

Interchangeable lenses can be sold separately, or they can come with the camera. So let’s also figure out what a camera lens is and its structure and main characteristics.

Camera Lens Design

To some extent, the camera lens mimics the human eye. The main task of the lens is to focus the light flux coming from various objects and form a focal point on the light-sensitive material.

Lenses play a primary role in optical design. These are glass plates of a round shape given a specific curvature by polishing and grinding. All photographic lenses are divided into the following groups:

  • Convex;
  • Biconvex;
  • Concave;
  • Biconcave.

Depending on the direction of curvature, lenses can be converging and diffusing. The first two groups are collective. They focus the light flux on one point. Thus, a convex photographic lens can play the role of the eye of a camera.

camera lens design
Camera Lenses Explained from A to Z

A photographic lens that has a single lens is called a meniscus. Such a simple optical system allows obtaining an image of an object on a light-sensitive material, but it will be of low quality.

The curvature of the optical glass changes from the periphery to the center, so the image of the object will be significantly distorted at the edges of the frame. Distortions of the picture are called aberrations and can be chromatic (color) and geometric.

Chromatic Aberration
Chromatic Aberration

In the first case, a colored border appears around the objects, disrupting the common perception of the photograph.

Geometric distortions are associated with the fact that rays passing through the central and peripheral parts of the photo lens are refracted at different angles. This entails curvature of straight lines or distortion, which can be in the shape of a barrel or pillow.

Geometric Distortion
Geometric Distortion

Additional lenses are installed in the camera’s optical set (frame) to eliminate all types of aberrations.

Types of Optical Systems

In developing practical lenses, lenses' optical design changed, and their design became more and more complex. After a meniscus consisting of a single photo lens, the following variations were developed:

  • Achromatic;
  • Aplanatic;
  • Anastigmat.
Camera Lenses Explained from A to Z
Camera Lenses Explained from A to Z

"Achromat" is a glued pair of two photo lenses. One of them is convex; the other is concave. There are no chromatic distortions in the photo lens of such a device, and geometric distortions are partially corrected. They are used on mobile phones and smartphones.

A more complex version - "aplanat or aplanatic," consists of two achromats. It resolves most of the problems associated with chromatic distortion, distortion and partially corrects astigmatism.

Lenses in which almost all aberrations are almost eliminated are called "anastigmat."

Modern Lens Design

Modern Lens Design
Modern Lens Design

The lenses of modern cameras belong to the anastigmatic and have a complex structure. It consists of several lenses of various curvatures and some technical devices located inside the optical system.

The number of photo lenses can be up to 15-20. They are usually grouped into several blocks. An ultra-thin coating of rare metal oxides is applied to the lenses to increase the image's contrast by damping glare.

Usually, lanthanum and its compounds are used for this purpose. This process is called enlightenment. In general, the optical system consists of the following units:

  • Lens blocks;
  • Diaphragm mechanism;
  • Stabilization system;
  • Fastening device;
  • Housing.

Lenses for the most expensive representatives are polished from a transparent type of fluorspar (also called fluorite) and have the lowest refractive index, making them suitable for use in super-telephoto lenses.

The distance between lenses and lens units is calculated with high precision. These values ​​determine the characteristics of the optics of the camera. Therefore, professional lenses have a rigid body made from durable and lightweight alloys. Plastic structures are cheaper but less reliable and may develop backlash over time.

Mechanical Components in Lens Construction

Camera Lenses Explained from A to Z
Camera Lenses Explained from A to Z

Let's consider the main mechanical components in the optical system.

Focusing Lens

The focusing lens plays an essential role in the lens design. Unlike other optical elements, which are rigidly mounted on seats, the focusing lens can move within the system. It is designed for focusing.

With older cameras, this process was done manually. For this, there was a corrugated ring on the photo lens, on which marks of the distance to the object being shot were applied.

On simple models without range finders, the distance was set "by eye" on a scale, where there were marks from 0.8 m to infinity (∞). The optical rangefinder reduced the likelihood of error since the photographer, due to the absence of "blurring" of the image in the viewfinder, precisely chose the desired distance.

Focusing Lens

The device of modern systems includes both an automatic focusing system using a miniature electric motor and the ability to set the focus point manually. The autofocusing algorithm may differ slightly depending on the camera manufacturer, but the results are usually the same.

Diaphragm

The diaphragm is a mechanical device located inside the lens between the lens groups. These are several thin metal plates; usually, 5-9, of a specific shape mounted on a rotating ring. The main task of the diaphragm is to limit the amount of light passing through the lens.

At maximum aperture, the lens is fully open. If you need to reduce the amount of light, then rotating the diaphragm ring selects a higher numerical value represented by a fraction, for example, f/1.4, f/2.8, f/8, and so on.

In this case, the plates of the device form a small hole between the photo lenses, comparable to a point. The second function of the aperture is to change the depth of field (DOF).

Diaphragm
Camera Lenses Explained from A to Z

With a strong aperture, all objects within the values ​​marked on the adjusting ring will be sharply displayed. In TTL SLR cameras, where the subject is viewed through optics coupled to the viewfinder through a prism and a system of mirrors, a "jumping" aperture is used. Focusing is carried out when the lens is fully open and only now of shooting the device instantly sets the preselected aperture value.

Image Stabilization

To optimize the shooting process, when it is impossible to use a tripod at long exposures, an optical image stabilization device is used. The device is based on gyroscopic sensors and a lens that can move freely in all planes.

The data from the gyroscopic sensors are sent to the microprocessor and by sending impulses to the electromagnets. It compensates for the movement of the camera by shifting the lens in the opposite direction.

Fastening System

Interchangeable lenses can be attached to the camera body in two ways:

Threaded Mount. Threaded lenses were used on older film cameras and are rarely used today.

Bayonet Mount. The mount "bayonet" quickly and reliably fixes the optics on the camera with a unique latch. Such a device allows the use of lenses with electronic control systems. For this, electrical contacts are provided on the body of the lens and the body of the camera, which are reliably closed after the installation and fixation of the optics.

Quality Level

According to experienced photographers, it is a good lens, not a camera, that is the key to quality photographs. Using a high-end lens and a mediocre camera, you can get great pictures, but a poor-quality lens can ruin the most winning scene, even on a professional camera.

Best - Often lenses, in terms of cost, can be several times more expensive than a good camera. The materials of construction mainly determine this. The highest quality and most expensive representatives of the class contain fluorite lenses in their devices. The optics body is made of ultra-light alloys that are used in space technology. These lenses are highly reliable and long-lasting.

Quality Level

Medium - Next is the lenses with quartz glass lenses. They provide good photo quality and are pretty reliable.

General - In the last place in terms of quality are lenses with acrylic lenses and plastic housing. It is awful if the bayonet mount is made of plastic. The backlash will be ensured with frequent replacement of optics even after a short time, and plastic lenses will quickly become cloudy from traces of dust and sand.

The lens is an integral part of the camera. It can be made as a simple aplanatic system and without various additional improving mechanisms. And in the form of a complex, bulky optical system, which includes about 20 lenses divided into blocks, automatic focusing systems, focal length changes, image stabilization, and various technological tricks that improve the quality of the captured image.

The cost of a lens can vary from easily lifted to almost any amateur photographer to prohibitively expensive - more expensive than a professional camera.

Types of Lenses

Types of Lenses
Types of Lenses

There are several types of lenses in the market; here, we will see the primary lenses.

1. Standard Lens

A standard or conventional lens has the same angle of view as the human eye without side vision. The focal length of such a lens is approximately equal to the frame diagonal. Almost always, such lenses have a high aperture (the aperture value characterizes this), which allows you to photograph at relatively short shutter speeds in low light.

2. Wide Angle Lens

Wide-angle lenses cover more angles than standard lenses. The shorter the focal length of the lens, the wider its angle of view. A lens with a focal length of 20 millimeters (for a 35mm camera) sees about 90 degrees of space along with the frame diagonal. All lenses with a focal length of 20 to 50 mm can be called wide-angle.

3. Ultra-Wide-Angle Lens

Ultra-wide-angle lenses are lenses with a focal length of 14 to 20 millimeters. They can be divided into two groups. These are straight lenses that produce images with no distortion or an acceptable level of perspective distortion and distortion, resulting in barrel distortion.

These lenses are also called fisheye (the name originated from the visual similarity between the lens and the fisheye). There are two types of fisheye lenses: 180 degrees diagonal of the frame (16mm) and 180 degrees vertical (8mm). With the help of the "fisheye," you can get an original effect and a kind of expressiveness.

Ultra-wide-angle lenses are used in reportage, architectural, interior, and landscape photography.

4. Telephoto (Long Focal) Lens

Long focal lenses bring the subject closer to the photographer. They can also be divided into two types: telephoto and ultra-telephoto lenses. They differ structurally. A negative lens has been added to the scheme in telephoto lenses. Thanks to which manufacturers have achieved a significant reduction in overall dimensions.

If you compare two lenses with the same focal length, a telephoto lens will be significantly smaller in size and weight. But it so happened that all telephoto lenses are also called zoom lenses.

5. Telescopic (Super Long Focal) Lens

These are lenses with a focal length of 500 mm or more. There are lenses with a focal length of 2000 mm, but this is already a rarity. The weight of such lenses is more than 6 kilograms, and shooting with them without a tripod is almost impossible. Almost all of them are equipped with a unique tripod mount.

A constructive type of ultra-long-focus lenses is a mirror lens. In such a design, spherical mirrors are part of the optical design. This design significantly reduces the weight and size of the lens, but it has some drawbacks.

Unfortunately, it is impossible to install a variable aperture in such lenses, which means that the exposure will have to be adjusted only with shutter speed and sensitivity. The light-tone pattern of such lenses is lovely; it is almost impossible to repeat it with any other lens.

6. Zoom (Variable Focal) Lens

This is the name for variable focal length lenses. Modern manufacturers can please you with a massive range of lenses of this type. These lenses are convenient: one such lens can replace several. You can more accurately build a composition in photography and significantly increase work efficiency, for example, in reportage, wedding, or sports photography.

But not everything is as good as it seems at first glance. Zoom lenses have drawbacks. Short throw zoom lenses suffer from distortion, and the faster the focal length (more extensive field of view), the higher the distortion.

In terms of aperture ratio, such lenses are divided into two categories: fixed and variable aperture. In the case of a variable aperture, the aperture changes depending on the change in focal length. For example, a 28-70 lens at a focal length of 28 mm has an aperture (aperture) of 2.8 and 70 mm - 4. This impairs usability - the larger the focal length, the lens aperture of such lenses.

Constant aperture lenses have no such disadvantages. As the saying goes, you must pay for everything in the world and the constant aperture of zoom lenses. They usually cost 1.5 to 2 times more than variable aperture.

7. Soft Focus Lens

A soft-focus lens or soft lens is usually produced with a set of removable apertures. The central opening (not equal to a specific working diaphragm) is surrounded by many smaller openings in such a diaphragm.

The center hole creates a sharp image, while the outer smaller holes scatter it. The diffusion level can be adjusted by replacing the insert diaphragm. This makes it possible to change the soft-focus effect and the degree of diffusion significantly. In some models, spherical aberration is not fully corrected on purpose.

8. Macro Lens

A lens that allows you to shoot without special equipment at a 1:1 scale. These lenses, unlike all the others, have aberrations corrected when shooting at a finite distance.

Macro Lens

9. Tilt Shift Lens

The name comes from the English word Shift; with the help of such a lens, you can get rid of perspective distortions by shifting the lens block parallel to the plane of the film or matrix.

It is the premier lens for those who want to capture architecture, cityscapes, or still live's without perspective distortion. When shooting, the camera is positioned so that the lens's optical axis is parallel to the ground.

Nikon PC-E ED Tilt-Shift Lens
Nikon PC-E ED Tilt-Shift Lens

When shooting from bottom to top, it is necessary to move the lens unit to ensure that the upper parts of the objects enter the frame. Accordingly, when shooting from top to bottom, the opposite is true.

There is certainly a constructive limit to this shift. And not always, for example, because of the height of buildings, it is possible to get rid of distortions. At the very least, perspective distortion will be minimal.

The cost of shift lenses is higher than that of conventional wide-angle lenses of the same focal length. Image processing software such as Photoshop can simulate perspective distortion correction.

Pentax-mount Arax 35 mm f2.8 Tilt-Shift Lens
Pentax-mount Arax 35 mm f2.8 Tilt-Shift Lens

Why imitation? Because of inaccurate shooting, a different perspective effect is created. Sometimes this fix is ​​noticeable. It is important to remember that interpolation occurs during computer distortion correction, which means that if there are many small details in the frame, the deterioration of quality will inevitably be inevitable. If the sky occupies most of the image, interpolation will not be noticeable.

10. Teleconverter

Structurally, the teleconverter cannot be classified as a lens. But with its help, you can increase the focal length, which means it will get closer to the subject. Small size and lightweight are the main advantages of the teleconverter.

Teleconverter
Teleconverter

The advantages include a relatively low cost. Converters are produced with a different magnification of the focal length. But the gain in focal length must be paid for by the loss of luminosity.

If the converter has a magnification of 1.5, then the aperture ratio drops by one-stop if the magnification is two by two visits. If you rarely use a long focal length, then it makes sense to purchase a teleconverter. But if you are shooting sports, concerts, or other subjects that require a lot of zooms, then it is worth getting a good telephoto lens.

Choosing A Lens for Your Camera

When choosing a lens, a beginner needs to focus first on the focal length. The task is to find which wide-angle, standard, or zoom lenses can be used for photography and are well known & reliable. Bellow table can help you to choose the lens type for your photographic requirements.

Focal LengthLensGoals of PhotographyVision Angle
4 - 16 mmFish EyeLandscape, Art, Specific Landscapes180° and more
10 - 24 mmSuper Wide AngleInterior, Landscape, Deliberate Distortion of Proportions84 - 109°
24 - 35 mmWide AngleLandscape, Architecture, Street Photography62 - 84°
50 mm (35-65)StandardLandscape, Portrait, Close-Up, and many more...46° (32 - 62)
65 - 300 mmZoomPortrait, Sport, Nature, Macro, etc.8 - 32°
300 - 600mm + moreUltra Zoom (Telephoto)Wildlife and Sports from a Long Distance4 - 8°

We will now combine the lens, the subject of photography, and the focal length into a more straightforward and more descriptive table. At the same time, one should understand the conventionality of any figure; it is impossible to argue that you cannot shoot people in total growth with a 300 mm lens or, say, a 24 mm wide-angle lens. Yes, even a fisheye. But for classic portraits, it is still better to use the indicated focal lengths because the geometric distortions inherent in wide-angle lenses are unacceptable.

PlotLensFocal Length
Landscape & InteriorWide AngleUp to 35 mm
People (Full Size)Wide Angle35-50 mm
Classic PortraitStandard + Zoom50-135 mm
Shooting Distant ObjectsTelephoto (Ultra Zoom)from 135 mm

Lens Aperture

In addition to the focal length, the lens aperture is also critical. What is it? Aperture is (very roughly) the ratio of the diameter of the aperture opening to the lens's focal length. To put it even rougher, it's just the size of the hole in the lens. 😊😊😊 And the larger it is, the more light comes in, and it is better to shoot in low light.

The aperture size can be adjusted with the aperture to control the depth of field and eliminate possible distortion.

Typical values ​​are: 1:1.4, 1:2, 1:2.8, 1:4, 1:5.6 , etc.

On the lenses themselves, the aperture ratio is precisely what they denote: through the colon space. The smaller the fraction, the smaller the aperture opening and vice versa. On all sites and literature, the designations were 1/1.4, 1/2.0, 1/2.8, 1/4, 1/5.6.

For brevity, the unit in front is often discarded, for example, 1.4, 2.0, 2.8. So often, instead of one, the letter "f" can be used: f/1.4, f/2.0, f/5.6, etc… And also without a fraction: f/1.4, f/2.0, f/5.6, etc.

Lens Aperture Ratio: Slow or Fast?

Lenses are fast and also slow or not very fast. What does it depend on? The maximum amount of light that can pass through the lens's optical system is limited by the diameter of the lens in its barrel. The larger this diameter, the more light will pass through, and the higher the aperture ratio. And the higher, of course, the dimensions, weight, and price: generally, the thicker the lens, the more expensive. 😉😉😉

Of course, I was joking. The price also depends on the lens manufacturing quality, their grinding, coating, lens assembly, and the quality of all its components. But back to the aperture ratio.

Aperture above f/2.8 (f/2, f/1.8, f/1.4, f/1.2) is characterized as a fast lens, but f/3.5 and below is slow or dark.

Everything is simple here: the larger the hole, the more light comes in, the better. Some amateur photographers seek to purchase the highest aperture lens, believing that it is easier for them to shoot in low light conditions. Such optics have more expansive possibilities for aperture control.

That's right, but even if you don't take into account the sobering blow to your wallet, you should always understand two things:

1. Even a very high aperture ratio of a lens is not an indicator of its quality, especially for inexpensive lenses from little-known companies. One of Zeiss Ikon's specialists, Wolf Veran, once said: "It is not the absolute maximum aperture that is important; the maximum aperture at which the lens can create a high-quality image is important."

Let me explain what has been said. Usually, to eliminate possible distortions and obtain sufficient sharpness, the photographer tightens the aperture: it is normal if 1-2 stops and excellent if it is unnecessary to do this. If high-aperture optics have to cover the aperture up to f/5.6 to get a good picture, such a lens is not worth the price.

On the other hand,5.6-8.0. It is outside this range that optical distortions of all sorts begin, for example, drop-in detail caused by open holes (and diffraction by closed ones). No need to look at hundreds of tests; we know from experience. But in high-quality optics, aberrations will not be critical for photography at an open aperture, and only then a high aperture ratio is a huge plus.

2. A high-aperture lens by itself does not give an exciting and creatively high-quality photograph.

Well, the advantages of such optics are well known. The fast lens is ideal for working in low light conditions, indispensable for photographing portraits, and attracts the ability to change the depth of field in a broader range.

When choosing a lens, in any case, I recommend starting with such concepts as focal length and aperture ratio: they are easily checked upon purchase because all this is written on the lens itself.

For those who choose interchangeable optics, it is helpful to know its designations. The table, which is available in a more detailed article, marking the lenses, I have given below and where they will come in handy.

Lens Markings

Lens CharacteristicCanonNikonPentaxSonySigmaTamron
BayonetEF/EF-SFKAF/KAF2AAnyAny
For full-frame (FF)EFFXFA-DG-
For Crop Only (APS-C Matrix)EF-SDXDADTDCDI II
Professional SeriesL--GEXSP
Image StabilizerISVRIn the CellIn the CellOSVC
Ultrasonic MotorUSMSWMSDMSSMHSMUSD
Internal FocusingI/RIFIF-IF/HFIF
Low Dispersion LensesUDEDED--LD/AD
Apochromatic Lenses---APOAPOHID
Aspherical LensesALASAL-ASPASL
Compact lensDO-Limited-UCXR

The hyphen "-" in the table means the absence of this characteristic (or the required information). Full frame lenses can generally be set to crop (APC-S sensor), but not vice versa.

Frequently Asked Questions
Frequently Asked Questions

1. How to find out the focal length and aperture of the lens?

They are indicated next to the frame. For example, consider the ancient Helios lens - we take it in our hands directly from the picture and just read it.

Let's start with the camera lens named 'MC Helios-44K-4'. This model has a multi-layer coating (letters "MC") and a bayonet mount "K" (the letters are visible in the name). The coating is needed to reduce light reflection from the lens surface. With the "K" mount, the lens can be installed on any camera with the same amount (and without any adapters). For example, on any Pentax SLR - even a digital one.

MC Helios Camera Lens
MC Helios Camera Lens

The lens has a constant focal length of 58 mm (see on the left of image), the aperture is indicated next to it - f/2 (designated 1:2). There is also a mounting thread for light filters - M52x0.75, lenses were produced for Zenit cameras with "K" mount.

2. What is lens mount and bayonet? 

A lens mount or bayonet is an interface – mechanical and often electrical – between a photographic camera body and a lens.

3. What is minimum focusing distance (MDF)?

MDF affects the zoom ability of the lens, and one of the main characteristics of a macro lens is that the shorter the focusing distance, the better. Allows you to focus on the subject from an extremely short distance (sometimes very close to the lens), i.e., capture "more object" into the frame. MDF begins its countdown from the matrix plane, and with macro lenses, this distance is always less than that of conventional optics with the same focal length.