Photographers may easily find themselves in a situation where they need to get closer to their subjects, but they can’t. It happens in sports, wildlife and bird photography, street and candid photography, and many other photographic genres. When you can’t physically get closer to a subject or don’t want to startle it, you need to find another way to magnify the image optically. The obvious solution would be to use a lens with a longer focal length. Although, super-telephoto lenses are expensive, heavy, and difficult to handle. And, sometimes, even a super-telephoto lens isn’t enough. Here is where a teleconverter can enter the scene. Check out how this accessory can change your lens kit.
What is a Teleconverter?
A teleconverter (or extender) is an optical device that mounts between the lens and camera body. It increases the focal length of the lens and, therefore, makes the subject seem closer to the camera. What a teleconverter does is crop the central area of the scene and magnify it. The result is a longer focal length and a narrower field of view. You can say it is a magnifying lens for the lens.
To find out how much the teleconverter increases the focal length of your lens, you have to multiply the focal length by the multiplication factor of the teleconverter. Teleconverters have a multiplication factor between 1.2x and 3.0x. The most popular factors are .4x and 2.0x. Therefore, with a 200mm prime lens and a 2.0x teleconverter, you achieve a focal length of 400mm. The same applies to zoom lenses. Teleconverters have the same effect over the entire range of focal lengths.
The teleconverter doesn’t change the minimum focusing distance of the lens, but it changes the maximum aperture. The same multiplication factor that increases the focal length decreases the aperture. For example, a 2.0x teleconverter decreases the maximum aperture by two stops; a 1.4x teleconverter by one stop. It means you won’t be able to achieve the same shallow depth of field as you would usually get with your lens.
How to Use a Teleconverter
Teleconverters mount as easily as lenses. The side that looks like the end of the lens goes into the camera and the other one into the lens. They weigh much less than the lens with the equivalent focal length, are more portable, and cost less.
If you prefer the quality and large maximum aperture of a good prime lens, you’ll enjoy extending your focal length range with teleconverters. It’s a good way to reach a focal length unavailable for a prime lens. They are also stackable, so you can keep multiplying your focal length. However, remember that the teleconverter decreases the maximum aperture of the lens, including diffraction which sets in a higher aperture numbers. Also, although one teleconverter may not impact image quality too much, with two or more teleconverters, the image quality will drop visibly.
Pros and Cons of Teleconverters
Consider all its advantages and drawbacks for the best results when using a teleconverter. For example, teleconverters work very well with macro lenses. They increase the magnification factor without changing the minimum focusing distance. As a result, you can capture the same amount of detail without losing your working distance or startling your subject.
However, teleconverters decrease the amount of available light and add diffraction softening by the same factor, as they increase the magnification.
To allow more light to enter the camera, you can either slow down the shutter speed or increase the ISO value. If possible, you can add artificial light sources and create a better illumination for your subject.
Because teleconverters increase the lens’s focal length, they also increase the risk of camera shake. So, make sure you use a solid tripod to stabilize the camera. Also, check if the image stabilization is still working after attaching a teleconverter. Not all lens-teleconverter combinations maintain this functionality.
Another drawback of using a teleconverter is a reduction in the autofocus performance. The autofocus system needs good lighting conditions to be able to detect and track the subject. Because the teleconverter reduces the amount of light that reaches the lens, the autofocus function will be slower or not functional at small apertures. With that in mind, it’s better to stick to teleconverters with a lower multiplying factor (e.g., 1.4x) when trying to capture fast-moving subjects. And perhaps use manual focus as much as possible in the rest of the cases, if you find that the teleconverter slows down your cameras autofocus too much.
How to Pick a Teleconverter
Check Your Lens
Teleconverters aren’t compatible with all lenses that have the same mounting system, although they do work with more than one lens. It’s a good idea to look for a teleconverter made by your lens manufacturer. With lenses and teleconverters made by the same company, you minimize the drop in image quality, risk of chromatic aberrations, lack of sharpness and contrast, reduced autofocus performance, and issues with lens calibration adjustments. However, an OEM teleconverter may be more expensive than a third-party one.
The brand is not the only thing you should check when buying teleconverters. Not all lenses support a teleconverter. As their purpose is to increase the focal length of the lens, teleconverters are mostly designed for telephoto and super-telephoto lenses. As a result, most wide-angle lenses and kit zoom lenses don’t support a teleconverter (either physically (you can’t attach it) or optically (you can attach it, but it doesn’t work)). The exception is macro lenses, which, even if they aren’t telephoto lenses, work very well with teleconverters.
Multiplication Factor
You should also consider the multiplication factor. The higher the multiplication factor, the longer the focal length. But at the same time, a high multiplication factor reduces the aperture, autofocus performance, and possibly image quality. A 3.0x teleconverter, for example, may reduce you to using only manual focus. It also decreases the aperture by three stops, which means slower shutter speeds or high ISO values and the risk of noisy images.
Furthermore, if you have a super-telephoto lens, to begin with, doubling or tripling the focal length may be too much for your typical subjects. The 1.4x and 1.7x teleconverters are more modest in focal length achievements but more versatile and with less impact on image quality and sharpness. Choosing a teleconverter should be a conscious decision. Commit to the changes they bring to your workflow.
Recommended Teleconverters
Nikon TC-20E III 2x
Designed for NIKKOR lenses (super-telephoto and others, see the compatibility list) and DSLR Nikon cameras, the TC-20E III features an aspherical lens and 2.0x multiplication factor. It promises no aberrations, reduced flares, and better color consistency and light transmission efficiency. It’s portable and allows you to handhold the camera without the risk of camera shake.
Nikon Z Teleconverter TC-1.4x
If you own a Nikon mirrorless Z camera, this teleconverter will provide a 40% increase in focal length while preserving all the qualities of your lens (e.g., resolution, autofocus performance, etc.). It’s compact, lightweight, and weather-sealed. Furthermore, it enhances the bokeh effect of NIKKOR Z lenses. If you need a higher multiplication factor, you can go for the 2.0x version.
Sony 1.4x Teleconverter for Sony FE 70-200mm GM & FE 100-400mm GM Lenses
Sony provides 1.4x and 2.0x teleconverters for its zoom telephoto lenses that aim to increase the focal length range without impacting the lens’ optical performance or AF speed. Perfect for sports and wildlife photography, the teleconverters are lightweight, compact, and dust and moisture-resistant.
Canon Extender EF 2x III
Even at a 2.0x multiplication factor, the Canon teleconverter provides exquisite sharpness, seamless communication with the camera, and minimized ghosting, flare, and chromatic aberrations. It is dust and water-resistant and weighs only 325g. The EF 2x III is compatible with many Canon EOS telephoto lenses, but AF and image stabilization aren’t possible for all of them.
Kenko 1.4x Teleplus HD DGX Teleconverter
If you need a teleconverter for Canon EOS EF-S and EF lenses, Kenko provides a solution that costs much less than the OEM correspondent. The Teleplus HD DGX provides a 40% increase in focal length, full electronic compatibility, and AF functionality. However, full AF functionality is possible only for lenses with an open aperture of f/4 or brighter.
Conclusion
Accessories provide versatility and allow you to take photographs in suboptimal conditions. Instead of struggling with camera settings, you can focus on composition and storytelling. If the limited focal length keeps you from taking a good photograph, teleconverters may be a solution.
But no accessory will do the work by itself. You have to choose your gear wisely and make sure everything is compatible. Then, you have to learn how and when to add the teleconverter to your workflow. Yes, a longer focal length makes the subject the star of the frame, but it also reduces the field of view. How do all these impacts your visual story? The most important aspect is knowing what you want to get from a scene and conveying it to your audience.
If you are looking for another option, check out What is an Extension Tube?
