Photographers often ask about teleconverters (TC) since they sound like a great idea. For a 200mm lens, you can use a 1.4x TC to "make it 280mm", a 1.7x TC makes it effectively 340mm and a 2.0x teleconverter turns it into a focal length of 400mm.
Of course, when you are using a TC you are also losing light and you will need to lower your f/stop ability by the same factor (an f/2.8 with a 2.0 TC attached turns into an f/5.6 lens). It sounds though that you can get yourself a much higher power lens on the cheap using a TC compared to buying the longer and more expensive lens. So, do these things really work?
Most photographers already know that that the higher magnification that you use, the more the image quality deteriorates. But is the result still usable? And does the image quality degrade that much for basic usage?
I have a mix of different lenses and teleconverters collected over the years and I am trying out some of them in combinations in this article attached to my Nikon D850.
For teleconverters, I have the same brands as lenses, Nikon, and Sigma.
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 below 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. Below is a photo taken at 200mm with no TC attached and that allowed me to use the 3D Focus Tracking. Without the 3D Focus Tracking, it would've become much harder to get the pelicans in focus.
Additionally, cropped down, this image is still very sharp.
With this lens, I used the Sigma TC-1401 1.4x teleconverter, making the effective focal range of the combo 216 - 850 mm. 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.
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 combination 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. Doing so and 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.
There are many Nikonians using all kinds of lenses with TC's on their Nikons and are very happy with the results. The experiments made by the author in this article are never the less interesting, especially the Nikkor 1000mm with the 2X TC-301 converter. Not too many of us have probably tried that combo before.
Nikon Canada Ambassador and wildlife photographer Michelle Valberg is using Z6ii and Z7ii with TC's and long lenses for birding and getting very pleasing results. You may want to see the webinar we held with her.
More to read on TC's
We have a very popular article on the technique of shooting birds in flight using TCs with many great sample images.
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