Canon EF 300mm f/4L IS USM EF300mm F4L IS USM Instruction Manual - Page 13

12. Extenders (Sold separately) With Extender EF1.4X ll or EF2X ll attached, the lens specifications will change as follows: Item Focal length (mm) Aperture Diagonal Angle of view Vertical Horizontal Maximum magnification (×) With EF1.4X ll Extender 420 f/5.6 - f/45 6°10' 3°20' 5° 0.33 With EF2X ll Extender 600 f/8 - f/64 4°10' 2°20' 3°30' 0.47 • First attach the Extender to the lens, then attach the lens to the camera. Detach it from the camera in the reverse order. If you attach the lens to the camera first, misoperation may occur. • With Extender EF2X II attached to the lens, only manual focus is possible. However, with the EOS1Ds Mark III, EOS-1Ds Mark ll, EOS-1Ds, EOS-1D Mark lll, EOS-1D Mark ll N, EOS-1D Mark ll, EOS-1D, EOS-1V/HS, EOS-3 camera, autofocusing with the center focusing point is possible. • Only one Extender can be attached to the lens and camera. • If you use an Extender on the lens mounted on a EOS A2/A2E/5, set the exposure compensation to -1/2 stop for the EF1.4X II or -1 stop for the EF2X II. • Autofocusing is still enabled with Extender EF1.4X II attached. • When an Extender is attached, the AF speed will become slower by design to retain proper AF control. ENG-12