The Pros and Cons of Teleconverters

Teleconverters seem like a dream come true: a cheap and easy way to increase the focal length of your lens. However, like most things in photography, there are pros and cons. This great video will walk you through what you need to know about teleconverters. 

Teleconverters are essentially secondary lenses that sit between the primary lens and camera body and magnify the center of the image, thereby effectively increasing the focal length. They're often chosen by wildlife and sports photographers who work with five-figure super-telephoto lenses and don't want to invest another five figures in another super-telephoto lens for a different focal length. And at a couple hundred dollars, they can be quite the comparative bargain, but they're not without drawbacks. Here's what you need to know:

• 1.4x and 2x: Teleconverters that increase the focal length by a factor of 1.4 and 2 are by far the most common. 
• Stops: A 1.4x teleconverter results in losing one stop of maximum aperture and a 2x results in a two-stop loss.
• Sharpness and Contrast: Both of these take a hit when using a teleconverter.
• Focusing Speed: Focusing speed slows down.
• Reduced Focusing Capabilities: Because the maximum aperture increases, many cameras will not use all their focus points with a teleconverter, often limiting them to the middle of the frame, while some will not use any at all, depending on the lens and camera combination. 
• Compatibility: Not all teleconverters are compatible with all lenses.

These may sound like a lot of cons, but when you compare spending $300-500 on a good teleconverter vs. several thousand on another lens, the prospects might shift favor. Watch the video above for some real-world scenarios. Personally, I'm of two minds when it comes to teleconverter usage: the image quality reduction with a 1.4x converter is often acceptable enough to justify its use, but 2x converters almost universally show a vast drop-off in quality. My personal preference is a middle road in terms of cost: buy a nice APS-C camera, which gets you 1.52x on Nikon and 1.62x on Canon. Both the Nikon D500 and Canon 7D Mark II are highly capable cameras that sidestep all the aforementioned drawbacks. At the end of the day, it's really a personal question of cost vs. quality and capabilities.