Overview

The Sigma 1.4x EX DG Tele Converter increases focal length by 1.4x with a 1-stop light loss. Optically, it can produce decently sharp images, especially in the center when stopped down to f/5.6–f/8, but sample variation is a concern: multiple copies showed significant right-side softness wide open on full-frame, though a later copy performed better. It is significantly cheaper than Canon/Nikon alternatives. Build and handling are standard, but it has compatibility issues: it will not mount on Nikon teleconverters and causes autofocus problems on Nikon lenses. It suits budget-conscious users with compatible Sigma lenses who are willing to test for a good copy.