Canon EF 800mm f5.6L IS USM - Manual (Page 7)

ENG-6
4. Infinity Compensation 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 L mark is
aligned with the distance indicator on the
distance scale.
For accurate manual focusing on subjects at
infinity distance, look through the viewfinder while
rotating the focusing ring.
The dedicated Lens Hood ET-155 helps to
prevent stray light from entering the lens and
protects the front of the lens from rain, snow or
dust.
To attach the hood, loosen the hood locking knob
by turning it counterclockwise. Fit the hood onto
the lens hood mount, and tighten the locking
knob to fix it in place. Use the same procedure,
in reverse, to remove the hood.
5. Hood
COP
Y