Zoom Ring - Canon EF 100-400mm f/4.5-5.6L IS USM Instruction

4. Adjusting Zooming Resistance
Move the zoom ring forward or backward to
zoom.
●
Be sure to finish zooming before focusing.
Changing the zoom ring after focusing can affect
the focus.
●
To prevent unintended extension of the front of
the lens, be careful not to set the zoom ring too
loose.
You can adjust the zoom ring "touch"
(resistance) as needed by holding the focusing
ring in place and turning the zoom touch
adjustment ring.
Turn the zoom touch adjustment ring towards the
word SMOOTH to reduce the zooming touch, or
towards TIGHT to increase it. To lock the zoom
ring in place, turn the zoom touch adjustment ring
towards TIGHT until it stops.
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