Camera following a moving object

I am trying to follow a moving space ship with the camera using global variables to pass the ship's position to the camera. It works, but the display jitters. Are there better ways? (Once movement works smoothly I want to mess with the ship's rotation, but leave the camera un-rotated.)

 public class Ship : MonoBehaviour {
 
     // global variables for passing ship position to camera
     public static float shipX;
     public static float shipY;
     
     // Initialization
     void Start () {
     }
     
     // Once per frame
     void Update () {
         transform.Translate(5f * Time.deltaTime, 0f, 0f);
 
         // globals for camera
         shipX = transform.localPosition.x;
         shipY = transform.localPosition.y;
     }
 }
 
 public class Cam : MonoBehaviour {
     
     private Vector3 newPosition;
 
     // Initialization
     void Start () {
     }
     
     // Once per frame
     void Update () {
         // follow ship with camera
         newPosition = transform.position;
         newPosition.x = Ship.shipX;
         newPosition.y = Ship.shipY;
         newPosition.z = -30f;
         transform.position = newPosition;
     }
 }