Hi Cho,
In order to revert to the original zooming, you need to rest the content area zoom factor:

NPolarChart polarChart = nChartControl1.Charts[0] as NPolarChart;
polarChart.ContentAreaZoomFactor = new NRectangleF(0, 0, 1, 1);
nChartControl1.Refresh();

Let us know if you meet any problems.

Best Regards,
Nevron Support Team

thanks.

and, how can I reset zoom?

It's not working.

axis.PagingView.Enabled = false

Hi Cho,

Currently, only cartesian charts support zooming and scrolling. The Chart in the .NET Vision suite supports zooming of polar charts trough the NPanelZoomTool:

nChartControl1.Controller.Tools.Add(new NPanelSelectorTool());
nChartControl1.Controller.Tools.Add(new NPanelZoomTool());

We hope this helps - let us know if you have any questions.

Best Regards,
Nevron Support Team

I tried, but can't zoom.