People often ask about teleconverters. They sound like a great idea. For a 200mm lens, you can use a 1.4x TC to make it 280mm. Or you can use a 1.7x TC and make it 340mm. Or a 2.0x TC and turn it into 400mm! Of course, you also have to lower your f/stop ability by the same factor (an f/2.8 with a 2.0 TC turns into an f/5.6 lens), but it sounds like for a lot less money, you can get yourself a much higher power lens on the cheap. Do these things work? Most people already know that that the higher magnification that you use, the more the image quality deteriorates. But is it still usable? And does the image quality degrade that much for basic usage? In this article we’ll take a look. I have a mix of different lenses and teleconverters collected over the years. A Sigma 150-600mm Contemporary, a Nikkor 200-500mm f/5.6, and an old Nikkor 1000mm reflex lens. For teleconverters, I have the same brands as lenses, Nikon, and Sigma. For the camera, I’m using a Nikon D850.
The Nikkor 200-500mm
The first lens we’ll look at is the Nikkor 200-500mm lens. The TC used was the Nikon AF-S FX TC-14E III. To try this combo out I went to a local bird sanctuary. The wind was blowing, and lens was catching the wind making it difficult to hold the camera still. I used a monopod to try and brace the camera for these photos. The combination of the lens and TC was able to produce sharp images. Figure 1 shows an image taken with this combination.
But here’s a problem. When I put the TC on the lens, I lost 3D Focus Tracking. Here’s a photo taken at 200mm with no TC at all. Without 3D Focus Tracking, this would have become very difficult to get in focus.
Additionally, cropped down, this image is still very sharp.
With a high enough resolution camera and quality lens, cropping is a better choice if you do not wish to lose function. In fact, for every TC I tried, there was a loss of function.
The Sigma 150-600mm Contemporary
With this lens, I used the Sigma TC-1401 1.4x teleconverter, making the combo 216-850mm. This combination caused autofocus to not work at all. Additionally, this is a very heavy combination (over 4.25 pounds) and trying to focus the lens manually while holding the camera steady proved to be very daunting. A monopod is required, and a tripod would be even better. For the next set of images, I went to the local zoo. By the time the day was done, my arms were quite tired from having to manipulate the camera and lens with the TC on it.
The Nikkor 1000mm f/11 Reflex Lens
This lens is large and bulky. The TC I used for it is the Nikon TC-301. Neither of these are made anymore. This is a fully manual lens, and with the TC, it becomes a 2000mm f/22 lens. This combination absolutely requires a tripod to hold the image steady, but even with that, taking pictures of anything that moves is made difficult by the f/22 lens aperture. During the brightest part of the day, the viewfinder appears so dark that you would think you have the lens cap still on. But you don’t, it’s just that dark. This lens/TC combo is so long, it’s hard to come up with a good subject. The following two images show just how much magnification you can get with this combination. For the next two photos, I went out to an overlook of a nearby bridge.
This lens/TC is so long and so dark you need to have a very fast shutter speed and a very high ISO value. One of the few things that works well with this lens is the moon, shown below.
Yes, you can use teleconverters with long lenses to make the lenses even longer. But it comes with a cost. You lose function, and you make taking a photo more difficult. It is a lot better, if you can, to not use a TC, and instead simply crop. You can retain autofocus, your image will still be sharp, and you’ll have all the functionality that your lens can provide. Each of the TCs tested here were recommended as the appropriate one for the lens they were used on, and they still caused issues. If you want a longer lens, instead of spending the money on a TC, save up your funds and simply buy a longer lens.
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