Also commonly called a "doubler".
It fits between the lens and the camera.
Your longest lens already have a 35mm equivalent of 450mm focal length.
Installing the doubler will give you 900mm focal length but will also change you exposure by about 2 f-stops.
Meaning you will need a lot of sunshine to use the lens.
And you would definitely need to put the camera on a sturdy tripod to steady the shot.
If you do not plan to carry a sturdy tripod, don't get the Tele Converter.
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I recently acquired a D90 and was trying to determine whether or not to buy an additional lens. The camera came with two VR lenses, 18-105 & 70-300. I will be taking a trip to South Africa and was wondering whether a tele converter lens would be helpful. Any help would be appreciated.
Thanks.

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