Personnally I would not put any extra glass between the lens and the camera body. I had several Canon FD lenses and sold them all. However it depends if you want quality images or just record type shots. The Canon 2 x converter at a few hundred quid actually degrades the image, I am not convinced about the 1.4x either. I had the Kenko Pro 1.4x and it severley degraded the Canon L series lenses I have. You are better going for quality glass and interpolating the image bigger at a low ISO. At a high ISO you can see the grain (and noise) increase in size as well. Sometime ago I also had a teleplus 7 element 2x converter, poor, I sold it, bought a second one, just the same, sold it. By modern standards these are awful. So I don't think you will get much for £23 or so. I have nothing against Roxen, they are a good outfit. Save your money and buy quality, it will last a lifetime.