## Lens

The **Lens** tool displays the area around the cursor at a magnified scale in the multi-function window, allowing you to examine a section of the chart in detail without changing the overall scale of the main window.

### Tool activation

The tool is activated by clicking the lens icon ![Lens](images/lens-icon.png) in the tool selection menu. When the tool is enabled, the active cursor changes to ![Lens cursor](images/lens-cursor.png), and a rectangular frame proportional to the multi-function window dimensions is drawn around the cursor.

```{important}
**In lens mode, chart panning is blocked!**
```

### Lens display

The lens is displayed in the **Multi-function window** under the **Overview** tab.

![Lens display in the overview window](images/Lens.png)

| № | Element | Description |
|---|---------|----------|
| **1** | **Viewing area** | The frame displays the area shown in the multi-function window |
| **2** | **Current scale** | ENC display scale in the multi-function window. Default is `x.1.2` |
| **3** | **ENC centering** | In Lens mode, if {{btn_center_on}} was enabled, it switches to {{btn_center_off}} |
| **4** | **Scale control** | Changing the ENC scale in the multi-function window. The scale can also be changed by rotating the mouse wheel |

```{warning}
ENC display density in **Lens** mode is preset and cannot be adjusted separately.
```

### Working with the lens

**Moving the viewing area:**

1. **Using the mouse:** move the cursor across the chart — the cursor and the area rectangle will move accordingly, with the chart in the overview window being redrawn
2. **On a touchscreen:** the cursor and rectangle are moved by touching the area of interest

**Changing the scale:**

When moving the cursor with the **left mouse button held down** or by **holding your finger on the touchscreen**, the scale will be **Best Scale x 1.5**.

### Operating features

**Display scale:**
- The multi-function window shows the chart at the **largest scale** within the area bounded by the cursor rectangle
- When holding the mouse button, the scale increases to **Best Scale x 1.5**

**Synchronization:**
- Moving the cursor on the main window automatically updates the image in the lens
- The rectangular frame follows the cursor movement
- The chart in the overview window is redrawn in real time
- Chart orientation — course-up

**Limitations:**
- Chart panning is blocked in lens mode
- To pan the chart, switch to another tool

```{tip}
**Use the lens tool to examine chart areas in detail without changing the main window scale.**

This is especially convenient when working with navigational objects, buoys, and other chart elements that require detailed study without losing the overall context of the main display.
```

```{note}
The dimensions of the lens rectangular frame are directly dependent on the multi-function window dimensions. When the window is resized, the frame automatically adapts.
```
