How to convert ist to est in c#

DateTime time1 = new DateTime(2011,04,20,17,57,33);
// DateTime time1 = new DateTime();// your DataTimeVariable

TimeZoneInfo timeZone1 = TimeZoneInfo.FindSystemTimeZoneById("India Standard Time");
TimeZoneInfo timeZone2 = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");

DateTime newTime = TimeZoneInfo.ConvertTime(time1, timeZone1, timeZone2);
Response.Write(newTime);