NorthStar 972 Quickstart Manual And Reference Manual page 114

Reference section 7 — Echo sounding
110
Zooming in and out
Bottom zoom
When you select bottom zoom, the contour
of the bottom is magnified, clearly
displaying canyon edges and echoes near
the seabed. The sounder automatically
locates the seabed and displays it on the
lower left side of the screen (normal echoes
are displayed on the right side).
If the seabed moves out of the lower half
of the screen (for example, if you travel
into deeper water), the sounder automati-
cally repositions the bottom back into the
lower half. You'll see the zoomed image
jump up or down from time to time, as the
sounder keeps the seabed displayed on the
screen.
Bottom zoom
Bottom lock zoom
Bottom lock zoom is similar to bottom
zoom, except the magnified sea bottom is
flattened-out and displayed on the left side
of the screen at the lower edge. You can
see any fish that are swimming near the
bottom.
Bottom lock zoom
Northstar 972