Basic knowledge of the lens that you want to know before starting the camera

When I start to investigate to buy a lens of a digital camera, various manufacturers make various kinds of lenses, and I do not know which one to buy. In addition, the storm of unknown terminology such as OSS and SSM … … There is no reason to think that it is good on a smartphone anymore.

Nonetheless, it is true that cameras made exclusively for photography are superior in various aspects over smartphones, and it is possible to obtain high quality photographs that cannot be photographed with small sensors of smartphones. It is not too difficult to figure out the lens to buy if you understand what you want and understand what each manufacturer calls each function with their name. If you learn a little technical term, you can decide which function is necessary for you and which function is not necessary.


“Aperture” of the camera lens is a function to adjust the amount of lighting the camera sensor. The open aperture value is determined for each camera, and it is defined by a unified standard called F value. Depending on the camera, the aperture is somewhere in the range F1.0 to F22. There are several notation methods of F value, for example F 2.8 may be written as “1: 2.8”. In any case, the same numbers have the same meaning and represent “open aperture value”.

The smaller the number of F values is (for example F1.8) the more diaphragm the more light will pass through the lens. A lens with a small F value (that is, a lens with a large amount of light striking the sensor) can create an effect called “blur”, so it is ideal for portrait photography. On the other hand, for the zoom lens, the range of the open aperture value is displayed as “F 3.5 – 4.5”. These two numbers are the open aperture values in the zoom range of the camera. The smaller number becomes the open aperture value on the zoom in side (F4.5 in this case).

Focal length

The focal length of a lens is the distance from the lens to the sensor when focused, and is defined in millimeters. A lens without a zoom function (such as a 35 mm focal length lens) has a single focal length. On the other hand, with zoom lenses the focal length is shown in the range (18-55 mm, for example). The shorter the focal length is, the wider range can be included in the picture. Wide angle lenses usually have a focal length of 10 mm to 33 mm, and for most cameras the focal length is displayed next to the F value.

Filter diameter

If you attach a filter to the lens, you can produce effects such as reducing glare and changing color. To use a filter, you must know the filter diameter of the lens. The filter diameter is defined in millimeters as well as the focal length, and it is displayed together with the “ø” mark. Usually it is engraved on the front of the lens or on the side of the side (the part where the filter is attached).

Autofocus and manual focus

With the auto focus lens, you can automatically focus on the subject without manually adjusting the depth of field. If there is a switch written “AF / MF” on the camera, it means that you can switch on / off this function quickly. By turning off autofocus it is possible to take pictures of the aimed atmosphere or to control the depth of field freely so that you can shoot in the studio.


Brand specific term

Other interesting lens functions are brand-specific terms and are a bit confusing. Do not get confused by the alphabet ‘s acronym. Even if the terms differ by brand, the technology used is almost the same.

Optical camera shake correction

Optical image stabilization is a function that is mounted on both the lens and the camera body, which suppresses shaking and vibration and prevents photographs from blurring. If you have camera shake compensation, you can take sharper pictures, especially with shooting with wide aperture . Terms by brand representing this function are as follows.

The full size camera has a large full size sensor, so you can collect more light and shoot high quality photos. In order to take full advantage of the performance of this sensor, a full size lens is necessary. There is also a full size sensor corresponding to lenses that are not full size, but the resulting photos will be those that do not use the whole sensor. Full size lenses are usually more expensive than lenses that are not. If you want to take high quality pictures, we recommend you to check about full size camera and full size lens.

Lens for compact sensors not full size

Small size sensors that are not full size are installed in cameras for consumers and photo enthusiasts. You cannot get the same quality as a full size sensor, but you can take pictures of higher quality than a smartphone.

Ultrasonic autofocus motor

Ultrasonic motors allow for a quieter and faster focus adjustment. Compared to inexpensive electric motors, you can continue to focus more accurately on subjects.

Professional grade lens

Professional grade lenses are designed to be incredibly accurate and sturdy compared to consumer grade lenses. Using high-quality glass, equipped with a high-speed autofocus motor, it is mostly waterproof and dustproof. Professional grade lenses are usually made for full size cameras and can make full use of full size sensors.

Low dispersion lens

Low dispersion lenses are made to solve the problem of chromatic aberration. Chromatic aberration is one of the camera’s characteristics that the color of a photograph is shifted due to incomplete refraction of light. Usually it occurs at the edge of the picture. Although there is software that corrects chromatic aberration, basically, unless you are professional, you will not notice that the color is misaligned. Low dispersion lenses solve this problem with special manufacturing techniques.

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