Canon EF70-300mm F4-5.6 IS USM Instruction page 12

10. Extension Tubes (Sold separately)
With Extension Tube EF 12 II or EF 25 II, the
camera-to-subject distance and image
magnification will be as follows:
Camera-to-Subject
Distance (mm)
Near
70mm 584
EF12 II
300mm 1361
70mm 420
EF25 II
300mm 1254
When an Extension Tube is attached, focus
manually.
Magnification
Far Near Far
638 0.22× 0.17×
7629 0.32× 0.04×
428 0.40× 0.38×
3890 0.39× 0.09×
11. Close-up Lenses (Sold separately)
Attaching a 500/500D or 250D (58mm) Close-up
Lens enables close-up photography.
The magnification will be as follows:
500/500D
70mm 0.14× - 0.22×
300mm 0.58× - 0.90×
¡Sales of the 500 Close-up Lens may already be
terminated in some areas.
¡When using a Close-up Lens, focus manually.
Magnification
250D
0.29× - 0.38×
Incompatible
ENG-11