Zoom Width; 83 Khz Sensitivity (Advanced, Dualbeam Plus™ Sonar Only [561]); 455 Khz Sensitivity (Advanced, Down Imaging™ Only [570 Di]) - Humminbird 561 Operation Manual

Zoom Width adjusts the width of the zoomed view on the Sonar Zoom View,
which is on the left side of the display. See Views: Sonar Zoom View for more
information.
83 kHz Sensitivity changes the sensitivity of the 83 kHz beam. Increasing the
83 kHz Sensitivity will display additional weak returns, and decreasing the
83 kHz Sensitivity will display fewer weak returns.
NOTE: 83 kHz Sensitivity is particularly useful for adjusting the sensitivity of the 83 kHz
sonar returns in the Split Sonar View. The 83 kHz sensitivity can be adjusted without
affecting the sensitivity of the 200 kHz returns shown in the 200 kHz sonar window.
455 kHz Sensitivity adjusts the sensitivity of the 455 kHz beam. Increase the
sensitivity to display additional weak returns and decrease the sensitivity to
display fewer weak returns.

Zoom Width

Settings: Narrow, Medium, Wide; Default = Wide
83 kHz Sensitivity
(Advanced, DualBeam PLUS™ Sonar only [561])
Settings: -10 to +10; Default = 0
455 kHz Sensitivity
(Advanced, Down Imaging™ only [570 DI])
Settings: -10 to +10; Default = 0
56 Sonar Menu Tab