Bottom Zoom (3D Sonar, 3D/2D Sonar Combo Views Only); Lower Range (3D Sonar, 3D/2D Sonar Combo, 6-Beam Sonar Views Only); History ( 3D Sonar, 3D/2D Sonar Combo Views Only) - Humminbird 748 3D Operation Manual

3D Bottom Zoom provides a magnified image of the bottom. Use 3D Bottom
Zoom to increase the detail of the bottom on the display.
3D Lower Range sets the deepest depth range that will be displayed.
Automatic is the default setting. When in automatic mode, the lower range will
be adjusted by the unit to follow the bottom. Selecting a specific setting locks
the depth range into Manual mode.
For example, if you are fishing in 60 feet of water but are only interested in the
first 30 feet (surface to a depth of 30 feet) you should set the Lower Depth
Range limit to 30. The display will show the 0 to 30 foot range, allowing you to
see a more detailed view than you would see if the display went all the way to
the bottom.
sonar information moves across the 3D display, and consequently the amount
of history shown.
A faster speed shows less history and is preferred by most anglers; however,
the sonar information moves across the display quickly.
A slower speed keeps the information on the display longer, but the bottom
becomes compressed and may be difficult to interpret.
3D Bottom Zoom
(3D Sonar, 3D/2D Sonar Combo Views only)
Off, 1.5x, 2x, 2.5x, 3x; Default = Off
Settings:
3D Lower Range
(3D Sonar, 3D/2D Sonar Combo, 6-Beam
Sonar Views only)
Settings: AUTO, 10 to 240 feet, 3 to 75 meters
[International Models Only]; Default = AUTO
3D History
(3D Sonar, 3D/2D Sonar Combo Views only)
Settings: Most, 2 - 9, Least; Default = 6
3D History determines the speed at which the
39 Sonar X-Press™ Menu