Canon EF 600mm f/4L IS III USM EF600mm f/4L IS III USM Instruction Manual - Page 27

18. Extenders (Sold Separately) 19. Extension Tubes (Sold Separately) Use an extender EF1.4× III or EF2× III to shoot a larger image of a subject. Lens specifications when using an extender are as follows. Focal length (mm) Aperture Horizontal Angle of view Vertical Diagonal Maximum magnification (×) EF1.4× III 840 f/5.6 - 45 2° 30' 1° 40' 3° 0.21 EF2× III 1200 f/8 - 64 1° 40' 1° 10' 2° 0.31 OO Attach the extender to the lens, and then attach the camera. To detach it, reverse the order. Errors may occur if you attach the extender to the camera first. OO Extenders cannot be used more than one at a time. OO If using an extender EF2× III, the maximum aperture is then f/8 and cameras that can shoot using AF are limited. Please refer to the camera's instructions for details. Use an extension tube EF12 II or EF25 II to get closer to a subject and shoot a larger image. Lens specifications when using an extension tube are as follows. EF12 II Focusing distance range (mm) Magnification (×) Close distance 3757 0.18 Long distance 29435 0.02 EF25 II Focusing distance range (mm) Magnification (×) Close distance 3382 0.21 Long distance 14187 0.05 OO MF mode is recommended for accurate focusing. OO When an extender is attached, the AF speed will become slower to retain proper control. ENG-26