Canon EF 300mm f/4L IS USM Instruction page 13

12. Extenders
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
• 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 EOS-
1Ds 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.
(Sold separately)
With EF1.4X ll Extender
420
f/5.6 – f/45
6°10'
3°20'
(×) 0.33
With EF2X ll Extender
5°
600
f/8 – f/64
4°10'
2°20'
3°30'
0.47
ENG-12