There are many scenes to shoot with a telephoto lens, such as motor sports, aircraft, and wild bird photography. It would be nice if the distance was short and you could shoot with a light telephoto lens such as 70-300mm, but if you want to express a sense of blur with a longer focal length or a large aperture lens, prepare a larger and heavier lens. In order to handle all kinds of subjects, I would like to carry several lenses with different focal lengths, but it takes a lot of effort to have many telephoto lenses weighing 1 kg or more. A teleconverter (extender) is convenient in such a case.
What is a teleconverter (extender)?
The teleconverter (extender) is an additional lens to extend the focal length of the lens. A teleconverter (extender) is an additional lens that is attached between the camera body and the lens. By attaching it, it is possible to extend the focal length of the lens by the magnification of the teleconverter (extender). From each manufacturer, 1.4 times and 2 times models are lined up. Select which magnification teleconverter (extender) to use depending on the shooting scene, the corresponding lens, and the camera body to be attached.
Convenient to carry when it is difficult to predict the distance to the subject
There are various shooting conditions, even if it is a scene that uses a telephoto lens. Some subjects have consistent movements such as distance to the subject and movements such as motor sports and aircraft takeoff and landing, while others such as wild birds and animals move freely. In that case, it is quite difficult to choose one lens with the optimum focal length, even for a veteran photographer who is quite accustomed to shooting. If you prepare a teleconverter (extender) for shooting, you can attach it when the focal length is not enough and get closer to the subject. Also, if you put it on and get too close to the subject, you can remove it and put it back. It is very convenient to carry it when you want to respond flexibly.
Advantages of teleconverter (extender)
Much smaller and lighter than preparing a lens
The biggest attraction of the teleconverter (extender) is its small size and light weight. It's about the size of a palm, so you can easily put it in your camera bag. The higher the magnification, the heavier the mass, but even a heavier full-frame SLR 2x teleconverter weighs less than 350g. It's much lighter and more compact than having another lens, so it's an overwhelming advantage to be able to extend the focal length.
You don't have to prepare multiple telephoto lenses with different focal lengths
The teleconverter (extender) can extend the focal length of the lens by magnification, so there is no need to prepare another telephoto lens with a long focal length. For example, if you attach a 2x teleconverter (extender) to a combination of a full-size machine and a 300mm lens, the focal length will be extended to 600mm. You can shoot powerfully close to the subject without having to prepare another large and heavy super-telephoto lens.
It is possible to shoot at a magnification close to that of a macro lens.
Even if a teleconverter (extender) is attached, the shortest shooting distance of the lens itself does not change. Therefore, depending on the combination of camera and lens, it is possible to shoot at a magnification close to that of a macro lens.
Disadvantages of teleconverter (extender)
Lenses compatible with teleconverters (extenders) are limited
According to DZOptics, teleconverters (extenders) are only compatible with a limited number of lenses and cannot be used with all lenses. If you try to attach it to an unsupported lens, the rear lens of the lens and the front lens of the teleconverter (extender) may come into contact with each other, or even if you can attach it, it will not work properly. Therefore, make sure to check the manufacturer's official website in advance to see if the lens you have or the lens you rent with it is compatible with the teleconverter (extender).
The maximum aperture value becomes dark
The teleconverter (extender) can extend the focal length, but the maximum aperture value will be darker by the same magnification. For example, if you attach a 2x teleconverter (extender) to a 300mm F4 lens, the focal length will change to 600mm, but the maximum aperture will change to F8. As a result, the feeling of blurring will be weakened and it will be difficult to increase the shutter speed, so be careful.
Autofocus cannot be used depending on the performance of the body
Please note that autofocus may not be available depending on the performance of the camera in connection with the darkening of the maximum aperture value . The camera is equipped with a sensor module for measuring the distance for autofocus, and the performance of this determines how many open F-numbers of the lens should be used for autofocus. For example, if you attach a lens that has been set to an open aperture of F8 by a teleconverter (extender) to a camera that operates autofocus only with an open aperture of F5.6 or less, you must focus manually. Most of the cameras are intermediate or above and are compatible with F8, but the corresponding aperture value will change depending on the AF point, so check it.
Image quality may deteriorate
By using a teleconverter (extender), the image quality may deteriorate to some extent. The reason is that, in general, the smaller the number of lenses, the higher the resolution tends to be. The light weakens as it passes through the glass, and the teleconverter (extender) has the same effect as adding glass to the lens to weaken the light. Also, since the lens is basically designed for use as a single unit, the image quality is higher when the teleconverter (extender) is not attached.
However, due to recent advances in technologies such as coating and optical design, deterioration of image quality has been minimized. Also, since the lens may be designed assuming the use of a teleconverter (extender) from the development stage, if the lens and teleconverter (extender) developed at the same time are combined, the resolution will not deteriorate much. prize.
