The Tamron SP AF Pro teleconverter features improved optical construction, and is designed to be used with lenses that are f/2.8 and of focal lengths of 90mm or greater.
Purchased this teleconverter to improve ability to capture shots of wildlife around the lake where I live. Results are supportive of my intended use. Sucks up a lot of light and does not work well in auto-focus mode without very bright environment. Manual focus is very easy and accurate.
