The new Canon Extender (converter) of the Series III to reiterate clearly in telephoto and super-telephoto optical performance and AF speed from Canon is unbroken. The Nikon and Sony-photographers like me do not be angry, but in comparison seems to me the obvious. Also very few Sony lenses can be used with the original converters. When converter lenses mean more = better correction = better image quality ', this equation has always been true in the converters. Canon has significantly increased from the seven-Linser and now come even 9 lenses used. Thus, the disadvantages of the converters are practically barely existent when the base lens is very good. The problem is still particularly at Canon, the converter can be combined with only a few lenses. Converters are primarily intended to compose the image of telephoto lenses to improve with a fixed focal length. Very few zoom lenses with Aperture f 2.8 and f: 4.0 are used meaningfully with converters. They should at least be dimmed by one step. Faint super zooms as 6.3 / 16-300 mm; 6.3 / 18-200 mm; 5.6 / 28-300 mm; 6.3 / 150-600 mm, you should not use with converter and faint telephoto zoom like: 5.6 / 70-300 mm; 5.6 / 100-400 mm; 6.3 / 50-500 mm; 6.3 / 150-600 mm allow virtually no good image results expected. The pure tele zooms you could on f: Fade 11 and raising through targeted post-contrast and sharpness to satisfactory image results from small animals or distant objects to obtain. You should always use a tripod and use ISO sensitivity of 1600 ISO and more. Better and cheaper is then definitely the much faster Panasonic FZ1000 even at f / 2.8 800 mm image detail still sharp, well-resolved image brings results, as long as enough light is there. Kenko and Sigma have at least reasonably good and flexible (with almost all lenses) 2x converter. The Canon Extender 2.0x works only with lenses of basic Aperture f: 2.8 with autofocus, or F: 4.0 at the latest cameras: Canon EOS 1DX; EOS 5D3; EOS 7D2 with AF, middle sensor - or he has to focus manually. However, manual work is in the super-telephoto range very difficult and time consuming and not necessarily recommended.
Who uses the 2x extender, is the 1.4x Extender rarely need. Furthermore 1.4x is still too little often with small motifs. Visually there at 2, ox Extender only an insignificant difference in resolution, depending on the lens. It is always better to get a sharp picture with 2x converter, as image files by a factor of 2x zoom out.
The autofocus is a little slower and need good subject contrast. In low light you focus manually safer. With the latest cameras, the converter works very well with the contrast AF in Live View on the monitor, then even combinations with AF with f / 5.6 L IS II 100-400 mm or 5.6 / 70-300 mm L IS and Tamron 6.3 / 150-600 mm VC possible. I do not want to give up prime lenses and converter, but by the Tamron 150-600 mm I am now much more flexible and sometimes faster, especially on the EOS 7D2 makes converter almost superfluous.
At Canon, the 2x converter with autofocus works only on the following objectives: 2.0 / 135 mm L 3,5 / 180mm L Macro 2.0 / 200 mm L IS 300mm f / 2.8 L II 300mm f / 2.8 L IS 2.8 / 400 mm L IS II 70-200mm f / 2.8 L IS II Sigma 300mm f / 2.8 Sigma 2.8 / 120-300 mm
and with the cameras: Canon EOS 1DX; EOS 5D3; EOS 7D2 with AF, only medium sensor: 4,0 / 300mm L IS 4.0 / 400 mm DO IS II 4.0 / 500 mm L IS II 4.0 / 600 mm L IS II 4.0 // 70-200mm L IS 4.0 / 70-200 mm L 4.0 / 200-400 mm L IS X1.4 Ext Sigma 4.0 / 500 mm
(And similarly designed variants older lens without IS and II)
