All you need to know about camera lens

Photographic Devices

In the world of photography, the camera lens plays a crucial role as it determines the quality of the captured image. Unlike the camera’s matrix, which simply converts the image into digital format, the lens is responsible for the formation of the image itself.

For a photographer to fully utilize the capabilities of their camera, it is important to have some understanding of how the lens works. While it may not be necessary to know all the technical details, knowing the basic principles of optics can greatly assist in making informed shooting decisions, utilizing all the features provided by the manufacturer, and properly adjusting the lens settings.

How the lens works

In contemporary devices, optical schemes incorporate multiple lenses to gather light that enters the sensor or film.

The supplementary lenses are intended to rectify the flow of light and correct any aberrations.

The functioning of a lens relies on the principles of optics – when a beam of light travels through substances with varying densities, it undergoes refraction.

The same principle applies to the objective lens. However, the refraction is significantly more pronounced at the interface between the optic material and the surrounding air. It is the curvature of the lens that enables the projection of an undistorted image onto the sensor, and the greater the convexity, the stronger the impact. Thus far, no company has been able to entirely eliminate distortion, and even meticulous camera calibration does not provide a remedy.

Main elements of the lens

There are various components that make up the lens design:

• The lens system;
• A metallic frame;
• An aperture.

The lens system is comprised of a collecting lens, optical mirrors, and additional lenses. The primary lens gathers light rays, while the others, along with the mirrors, refract these rays and transmit the image to the matrix.

Depending on the intended use, the lens may contain multiple lenses, which can either have an air layer between them or fit tightly together.

BACKGROUND. Simple apparatuses typically have 1 to 3 lenses, while professional equipment may have 10 or more lenses.

The lens body or frame is constructed from metal and is responsible for securing and strengthening the lens system.

The frame is composed of two parts:

• The first, or outer part, protects against external negative factors and physical damage. The lenses and diaphragm are attached to this part.
• The inner or adapter portion is in charge of the axial movement of the components and also functions as a mounting element for attaching to the camera. Another crucial role of the adapter portion is to regulate the aperture, whether it be done manually or automatically.
• The aperture consists of a movable metal petal that is lined with an adjustable opening. During the process of capturing an image, it manages the quantity of rays that come into contact with the lens.

Focusing and image stabilization mechanism

The camera’s lens is not the sole factor that determines the photo’s quality. The focusing ring provides the ability to achieve sharpness in both manual and automatic modes. Its operation principle is straightforward – rotating the ring shifts the focus towards the background or foreground.

Certain models feature a screwdriver drive. This motorized mechanism within the camera enables the movement of specific lens components during the focusing process.

The system is characterized by two drawbacks: slow operation and strong noise. It is worth mentioning that Nikon has been incorporating autofocus into its cameras since 1986.

The advanced models come equipped with a silent autofocus feature. The motor for autofocus is not located within the camera body, but rather in the lens.

Optical stabilization is employed to prevent image blurring. This functionality is achieved through a small element integrated into the lens, which operates in either normal or active mode. The latter mode is typically activated in instances where there are significant air disturbances or when capturing moving subjects. In the absence of a stabilizer, a tripod becomes essential.

Types of lenses and their application

When someone first gets into photography, they typically start out with a camera that comes with a kit lens. As they become more experienced, they realize that different types of lenses are needed for different types of photography.

Camera lenses are categorized based on shooting conditions, optical characteristics, lens structure, and the number of lenses involved.

There are cameras that have lenses that do not extend when focusing on a subject. This is known as internal focusing, where the focusing happens inside the camera and is achieved through the movement of the lenses. This feature ensures that the camera will last longer and is particularly useful for shooting with light filters.

Whale

For newcomers, a device with kit optics is a versatile choice. The field of view of this camera is similar to that of a human, excluding peripheral vision.

This camera is ideal for all types of photography, including capturing subjects in motion. It is affordably priced, but the resulting videos will range significantly in quality, from exceptionally high to extremely low.

The camera possesses a generous field of vision, spanning 60 degrees, accompanied by a focal length of up to 28mm. Its purpose? Ideal for capturing stunning architecture, breathtaking landscapes, and expansive group portraits.

When using a wide-angle lens, the photographer needs to possess a great deal of expertise, as this kind of gear is accompanied by linear and perspective distortions.

Fisheye

The "fisheye" lens, also known as a wide-angle lens, is known for its unique and exaggerated distortion. This lens offers a viewing angle of 180 degrees and has a variable focal length ranging from 4.5 to 15 mm.

What purposes do they serve? They enable you to capture diagonal and circular shots, making them ideal for capturing extreme sports, cityscapes, and creating extraordinary spatial distortions.

Lens for macro photography

What lens options are available for macro photography? There are a variety of lenses designed specifically for capturing small subjects. These lenses can have focal lengths ranging from 30 to 300 mm. One of the key benefits of using such a lens is the ability to achieve exceptional image sharpness and accurate color reproduction.

Macro photography lenses are commonly employed for capturing images of flowers and insects. Additionally, many macro lenses also have the capability to capture stunning portraits.

These lenses possess a focal length range of 70 to 300 mm. The field of view amounts to 39 degrees. Categorically speaking, they are classified as both long-focus and telephoto lenses, employed for capturing images of dynamic subjects.

Their weight is considerable. In the case of telephoto lenses, it is diminished because of the inclusion of a negative lens.

Portrait optics

These lenses possess a high aperture value and an unchanging focal length. They enable you to hide blemishes on the skin thanks to the soft focus they provide.

For every type of portrait photography, a specific focal length is required:

• If you are capturing a close-up of a person’s face, the ideal range is 70 to 135 mm;
• For a half-body portrait, a 50mm lens is recommended;
• If you are taking full-length portraits of individuals, a focal length between 24 and 35 mm is recommended.

For beginners, a lens with a focal length of 50 to 100 mm is suitable.

When it comes to selecting a camera, there are a few key factors to consider and keep in mind.

Firstly, one important aspect to pay attention to is the focal length of the camera lens. This parameter plays a significant role in determining the quality of the photographs taken. Cameras with shorter focal length lenses have a wider field of view, which means that as the distance increases, the angle of view becomes smaller. The focal length also impacts the transfer of perspective in the photographs. A wide-angle lens, for example, has the ability to visually enlarge the distance between objects and add depth to the image. On the other hand, using a long lens compresses the perspective and reduces the perceived distance between subjects.

Luminosity. The luminosity determines the lens’s ability to transmit light, and the wider the aperture, the more light reaches the lens. In shaded areas, this indicator is crucial for photography. Professional cameras have aperture values ranging from f/1.8 to f/2.8, which adds to their weight. Amateur devices are less light-sensitive but weigh less.

Image stabilization system. Originally developed for video cameras to ensure smooth footage, modern cameras incorporate image stabilizers that enable photography even in situations where flash or tripod use is not feasible. However, some electronic stabilizers may crop the image.

• There is a significant debate surrounding lens mounts in the photography world. Each manufacturer designs mounts exclusively for their equipment, meaning that there are no universal standards. Therefore, when selecting gear and lenses, it becomes necessary to first decide on a manufacturer.
• The material from which a camera is constructed is also a crucial factor to consider. Opting for a camera with numerous aspherical and apochromatic elements will result in a more contrasting image, increased sharpness, and reduced distortion.

NOTE: It is not recommended to purchase lenses with low dispersion glass as they can diminish chromatic aberration.

When it comes to photographic equipment, the primary players in the market are Nikon and Canon. Professionals have consistently praised the reliability and user-friendliness of products from these two manufacturers.

How to correctly perform a change of lens

The cost of SLRs and optics is quite expensive, and there are several main risks associated with handling optics:

What should I keep in mind when replacing the lens? It is important to hold the device with the aperture facing downwards, and it is not advisable to make any changes while on the move, as this greatly increases the risk of breaking the glass or damaging the sensor.

The lens replacement process should ideally take place in a clean and draft-free environment.

To remove the lens, use the fingers of the left hand to unlock the button and unscrew the optics in a counterclockwise direction. Once removed, immediately cover the lens with a protective cover or place it inside a case to prevent exposure to sunlight, moisture, or dust.

The fastening process involves using red or white dots for securing, with the specific color depending on the manufacturer. After the optic is placed into the grooves, it is screwed until a distinctive clicking sound is heard.

PRO TIP: If you encounter difficulties in opening the lens mount, attempt removing the memory card and battery, then reinsert them and give it another shot.

What exactly is lens alignment? Lens alignment involves the calibration of optics to achieve optimal performance by adjusting the position of all lenses in order to enhance sharpness.

If there are gaps, increased "backlash", or loose optics, adjustment is necessary. These issues can arise from mechanical damage or be the result of a factory defect.

Adjusting lenses requires some experience and knowledge, but it is simplified if the camera has the "Live View" feature.

If this feature is available, you can adjust the camera using the following steps:

• Mount the camera on a tripod;
• If available, turn on stabilization;
• Open the aperture;
• Focus on the desired subject using Live View.

Once the test has been completed, deactivate the function and switch the unit to "One-Shot AF" mode without making any changes to the focus. Proceed to gently release the shutter or press the "AF" button. During this time, it is expected that the focus ring will be operational. In the event that it remains stationary, there is no need to make any adjustments to the camera.

If the focus ring does indeed move, it is essential to take note of the direction in which it moves. If a manual focus adjustment feature is available, it is possible to manually adjust the lens.

Lens alignment involves a mechanical calibration process, which necessitates the use of a microscope, a collimator, and a focal length measurement grid. Consequently, it is recommended to seek assistance from a service center for precise adjustment.

Cleaning the lens at home

Proper maintenance is necessary for lenses, particularly when shooting in windy or rainy conditions. Cleaning larger diameter optics requires a more meticulous approach.



Every photographer should understand how to care for their optics. The process should be performed in a clean environment and will require a special air blower, brush, pencil, or microfiber cloth.



When cleaning at home, follow these steps:




• Use an air blower to remove any debris by holding it as close to the lens as possible;



• Use a brush to remove remaining dirt and dust particles;



• If there are any oily streaks on the lens, eliminate them with special quick-drying alcohol-based solutions.



If there is still debris remaining even after completing all the procedures, it is possible to remove it using a specialized pencil. This pencil has two sides, one with graphite for removing stubborn debris and another with a softer texture.

IMPORTANT: It is strictly prohibited to clean the lens with cotton discs as they leave behind particles that can result in even more contamination in the future.

Having a basic understanding of cameras, lens alignment, and potential malfunctions, as well as knowing how to diagnose and resolve them, is crucial for any photographer.

For various shooting conditions, a professional photographer always keeps a complete set of lenses readily available.

Inspect the lens focus directly in the store. It is essential to concentrate on a well-illuminated object with significant contrast and capture multiple shots. If the object remains consistently in focus, then everything is in proper working order. However, if the focus fluctuates, it is advisable to reconsider your purchase decision to avoid future headaches with lens adjustments.