本コンポーネントでは、マウスホィールによる組み込みのズーム操作では第１Y軸のみがズームされ、第２Y軸は自動的にズームされません。

第２Y軸もズームさせるには、第１Y軸のズームに第２Y軸の表示範囲を手動で同期させる必要があります。
そのためには、RangeChangedイベントを使用し、第１Y軸の表示範囲の変化量に応じて、第２Y軸の表示範囲を調整してください。



以下に簡単な設定例を記載します。

◎サンプルコード（VB）

Imports C1.Chart
Imports C1.Win.Chart


Public Class Form1
    Private axisY2a As Axis

    Private y1Min0 As Double
    Private y1Max0 As Double

    Private y2Min0 As Double
    Private y2Max0 As Double

    Public Sub New()
        InitializeComponent()

        ' 第1Y軸(デフォルト)
        FlexChart1.AxisY.AxisLine = True
        FlexChart1.AxisY.Min = 0
        FlexChart1.AxisY.Max = 10
        FlexChart1.AxisY.MajorUnit = 2
        FlexChart1.AxisY.MajorGridStyle.StrokeColor = Color.Silver
        FlexChart1.AxisY.Title = "系列1"
        FlexChart1.AxisY.TitleAngle = -90

        ' 第2Y軸
        axisY2a = New Axis()
        axisY2a.AxisLine = True
        axisY2a.Min = 0
        axisY2a.Max = 100
        axisY2a.MajorUnit = 20
        axisY2a.Position = Position.Right
        axisY2a.Title = "系列2"

        ' 初期レンジを保存
        y1Min0 = FlexChart1.AxisY.Min
        y1Max0 = FlexChart1.AxisY.Max

        y2Min0 = axisY2a.Min
        y2Max0 = axisY2a.Max

        ' 系列1
        Dim series1 As New Series() With {
                .Name = "系列1",
                .ChartType = ChartType.Column,
                .DataSource = New Point() {
                    New Point(1, 2),
                    New Point(2, 1),
                    New Point(3, 4),
                    New Point(4, 3),
                    New Point(5, 5)
                },
                .Binding = "Y",
                .BindingX = "X"
            }

        ' 系列2
        Dim series2a As New Series() With {
                .Name = "系列2",
                .ChartType = ChartType.LineSymbols,
                .DataSource = New Point() {
                    New Point(1, 30),
                    New Point(2, 20),
                    New Point(3, 50),
                    New Point(4, 40),
                    New Point(5, 60)
                },
                .Binding = "Y",
                .BindingX = "X",
                .AxisY = axisY2a
            }

        FlexChart1.Series.Clear()
        FlexChart1.Series.Add(series1)
        FlexChart1.Series.Add(series2a)

        FlexChart1.Legend.Position = Position.Bottom

        ' ズーム
        Dim zoom As New C1.Win.Chart.Interaction.ZoomBehavior()
        zoom.Mode = C1.Win.Chart.Interaction.GestureMode.XY
        FlexChart1.Behaviors.Add(zoom)

        ' パン
        Dim translate As New C1.Win.Chart.Interaction.TranslateBehavior()
        translate.Mode = C1.Win.Chart.Interaction.GestureMode.XY
        FlexChart1.Behaviors.Add(translate)

        ' Y軸レンジ同期
        AddHandler FlexChart1.AxisY.RangeChanged, AddressOf AxisY_RangeChanged
    End Sub

    Private Sub AxisY_RangeChanged(sender As Object, e As EventArgs)
        Dim y1 = FlexChart1.AxisY
        Dim ratio As Double =
                (y2Max0 - y2Min0) /
                (y1Max0 - y1Min0)

        axisY2a.Min = y2Min0 + (y1.Min - y1Min0) * ratio
        axisY2a.Max = y2Min0 + (y1.Max - y1Min0) * ratio
    End Sub
End Class

◎サンプルコード（C#）

using C1.Chart;
using C1.Win.Chart;
using System;
using System.Drawing;
using System.Windows.Forms;

namespace prj_FlexChart
{
    public partial class Form1 : Form
    {
        Axis axisY2a;

        double y1Min0, y1Max0;
        double y2Min0, y2Max0;

        public Form1()
        {
            InitializeComponent();

            // 第1Y軸(デフォルト)
            flexChart1.AxisY.AxisLine = true;
            flexChart1.AxisY.Min = 0;
            flexChart1.AxisY.Max = 10;
            flexChart1.AxisY.MajorUnit = 2;
            flexChart1.AxisY.MajorGridStyle.StrokeColor = Color.Silver;
            flexChart1.AxisY.Title = "系列1";
            flexChart1.AxisY.TitleAngle = -90;

            // 第2Y軸
            axisY2a = new Axis();
            axisY2a.AxisLine = true;
            axisY2a.Min = 0;
            axisY2a.Max = 100;
            axisY2a.MajorUnit = 20;
            axisY2a.Position = Position.Right;
            axisY2a.Title = "系列2";

            // 初期レンジを保存
            y1Min0 = flexChart1.AxisY.Min;
            y1Max0 = flexChart1.AxisY.Max;
            y2Min0 = axisY2a.Min;
            y2Max0 = axisY2a.Max;

            // 系列1
            Series series1 = new Series()
            {
                Name = "系列1",
                ChartType = ChartType.Column,
                DataSource = new Point[]
                {
                new Point(1, 2),
                new Point(2, 1),
                new Point(3, 4),
                new Point(4, 3),
                new Point(5, 5)
                },
                Binding = "Y",
                BindingX = "X"
            };

            // 系列2
            Series series2a = new Series()
            {
                Name = "系列2",
                ChartType = ChartType.LineSymbols,
                DataSource = new Point[]
                {
                new Point(1, 30),
                new Point(2, 20),
                new Point(3, 50),
                new Point(4, 40),
                new Point(5, 60)
                },
                Binding = "Y",
                BindingX = "X",
                AxisY = axisY2a
            };

            flexChart1.Series.Clear();
            flexChart1.Series.Add(series1);
            flexChart1.Series.Add(series2a);
            flexChart1.Legend.Position = Position.Bottom;

            // ズーム
            var zoom = new C1.Win.Chart.Interaction.ZoomBehavior();
            zoom.Mode = C1.Win.Chart.Interaction.GestureMode.XY;
            flexChart1.Behaviors.Add(zoom);

            // パン
            var translate = new C1.Win.Chart.Interaction.TranslateBehavior();
            translate.Mode = C1.Win.Chart.Interaction.GestureMode.XY;
            flexChart1.Behaviors.Add(translate);

            // Y軸レンジ同期
            flexChart1.AxisY.RangeChanged += AxisY_RangeChanged;
        }

        private void AxisY_RangeChanged(object sender, EventArgs e)
        {
            var y1 = flexChart1.AxisY;

            double ratio =
                (y2Max0 - y2Min0) /
                (y1Max0 - y1Min0);

            axisY2a.Min = y2Min0 + (y1.Min - y1Min0) * ratio;
            axisY2a.Max = y2Min0 + (y1.Max - y1Min0) * ratio;
        }
    }
}