Using bottom zoom
Using bottom lock zoom
•marker zoom
The original unzoomed echoes are on the right side, and the magnified area is shown on the left side of the screen.
A tab below the ZOOM key shows which zoom mode is in use.
When you select bottom zoom, the contour of the bottom is magnified, clearly displaying canyon edges and echoes near the seabed. The 491 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 491 automatically repositions the bottom back into the lower half. You’ll see the zoomed image jump up or down from time to time, as the 491 keeps the seabed displayed on the screen.
When you select bottom lock zoom, 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.
Page 20 | 491 Echo Sounder Operations Manual |
