Canon EF 400mm f/4 DO IS II USM EF400mm f/4 DO IS II USM Instructions - Page 16

9. Infinity Compensation 10. Hood Mark Infinity compensation mark Distance index To compensate for shifting of the infinity focus point that results from changes in temperature. The infinity position at normal temperature is the point at which the vertical line of the distance scale L mark is aligned with the distance index. For accurate manual focusing of subjects at infinity, look through the viewfinder or look at the magnified image* on the LCD screen while rotating the focusing ring. * For cameras with Live View shooting capability. The special hood that comes with the lens cuts out unwanted light and protects the front of the lens from rain, snow, and dust. To attach the hood, loosen the hood lock knob by turning it counterclockwise. Fit the hood onto the lens's hood mount, and tighten the lock knob to fix it in place. Use the same procedure, in reverse, to remove the hood. ENG-15