The TC-1401 focal length converter increases the focal length of lenses by 1.4 times, e.g. a 300mm f/4 lens becomes a 420mm f/5.6.

The Sigma TC-1401 is designed for Sigma's latest telephoto lenses. The teleconverter works with autofocus on the following lenses:
The TC-1401 focal length converter increases the focal length of lenses by 1.4 times, e.g. a 300mm f/4 lens becomes a 420mm f/5.6. This means that the light output is also reduced by one stop.
The product may be so-called bulk-packed (no sales packaging). However, it comes with an instruction manual and the product is new and includes a full warranty.