Excerpt: Bought this product to use with a Canon 70-300DO lens for protability in the field. It works well so far and I have tested it on other lenses including 28-135. It AF at all ranges and all the lenses tested. Also on several Canon camera bodies from Pro to a 30D.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Lightweight
Summary: In my Book It gets 5 stars all around , It up there too with the my Kenko 1/4 Tele converter from the first time I use it. It was awesome , I love having options available to me when I'm traveling and shooting Pix , I like to travel light and shoot a wide range of subjects , from close ups micro...
Summary: Excellent Teleconverter, its pretty cheap with extra-good quality, compared to other more expensive brands, designed to be best for use with longer telephoto lenses. When using with over 100mm lenses, it improves the resolution at the peripheral corners skipping deterioration of light.