In recent years, some companies take a dual-camera system to improve the magnification ability and zoomed image’s quality in multi-function imaging devices. The solution comprises two apertures to perform a large zooming range without any mechanism moving optical elements: one with a wide-angle lens for lower magnification and the other with a telephoto lens for higher magnification. Nevertheless, this dual-camera system still needs to interpolate the digital zoomed image between the lower and higher magnification images results in a discontinuous quality of zoomed image. We propose a distorted lens (DL) dual-camera system with varying focal length for higher magnification performance and smoother optical zoom. The proposed optical system has a greater pixel count per field angle at the center of sensor than at the periphery of sensor. Therefore, we sacrifice some resolution of the peripheral FOV to enhance the resolution of the center FOV for improving the capability of magnification. For instance, using a 20 MP sensor and displaying a Full HD zoomed image, the maximum magnification factor of 7.54 is achieved in our distorted lens system, but this factor of 3.12 in the distortionless lens system. In other words, we raise the capability of magnification up to 242%.