Review on Canon Telephoto Extender Super Lenses by Amanda Tiwari

I am currently using it on my Canon 70-200 f4 L IS with EOS 7D. I chose 70-200 f4 IS over f2.8 mainly for IS and weight. I can still get good shots with a teleconverter at f5.6 and IS helps a bit. When I use it with a 70-200 f4L IS I get the equivalent: 98-280mm and f5.6 - f45. with 70-200 F4L IS and EOS 7D you get about: 157-448mm and the same aperture. I'll try to post some sample images for the product description above because 'they' don't allow us to post links here. :-(PROS: Extends the life of professional Canon L lenses with little or no noticeable degradation in image quality. PRICE: Only works with select Canon and third-party lenses. Some third-party teleconverters such as Sigma and Tamron work with other lenses that this TC will not will be due to the protruding element but I just can't believe they are of such good quality 29/13 it says on the Canon website: 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L and EF 100-400/ 4.5-5.6 liters.