Canon EF28-300mm f/3.5-5.6L IS USM Instruction page 14

13. Extension Tubes
You can attach Extension Tube EF12 II or EF25
II for magnified shots. The shooting distance and
magnification are shown below.
Camera-to-Subject
Distance (mm)
Near
28mm 265
EF12 II
300mm 604
28mm
EF25 II
300mm 541
Manual focusing is recommended for accurate
focusing.
(Sold Separately)
Magnification
Far Near Far
277 0.50× 0.43×
7594 0.39× 0.04×
Incompatible
3730 0.50× 0.09×
ENG-13