OrthographicSize on Android changes from Start to Update?

I'm making a 2D game for Android and most scenes are in portrait mode, but one is in landscape. In the landscape scene, I want the player to be able to zoom and pan the camera. The problem is that when I run the game on my Android phone (HTC One: 1920 x 1080 screen), the original aspect ratio calculated in the Start function shows as portrait (AR: 0.5625), and the AR calculated during the Update function shows as landscape (AR: 1.7778). Running the game in Unity with 1920 x 1080 screen gives expected results with both original and current AR showing as 1.7778. Any idea why the AR in Start is different on Android than in Unity? This is preventing the camera from calculating the correct clamping values. Here is the entire zoom and pan script:

 #pragma strict
 
 var cameraZoomSpeed : float = 0.1f;        // The rate of change of the orthographic size in orthographic mode.
 var maxZoom : float = 3.25f;
 var minZoom : float = 2.0f;
 var dragSpeed : float = 0.5f;
 private var oldPosition : Vector2 = Vector2.zero;
 
  var originalHalfHeight : float;
  var originalHalfWidth  : float;
 private var resetDrag : boolean = true;
  var min : Vector2 = Vector2.zero;
  var max : Vector2 = Vector2.zero;
 
 var currentHalfHeight : float;
 var currentHalfWidth  : float; 
 
 var originalAR : float;
 var currentAR : float;
 
 function Awake()
 {
     Screen.orientation = ScreenOrientation.LandscapeLeft;
     Camera.main.orthographicSize = maxZoom;
 }
 
 function Start()
 {
     originalAR = Camera.main.aspect;
     originalHalfHeight = Camera.main.orthographicSize;
     originalHalfWidth  = originalHalfHeight * Camera.main.aspect; 
 }
 
 function Update()
 {
     if(Input.touchCount == 0)
         resetDrag = true;
 
     if(Input.touchCount == 1)
     {
         var newPosition : Vector2 = Input.GetTouch(0).position;
         
         if(resetDrag)    // keeps the screen from jumping when player first touches down
         {
             oldPosition = newPosition;
             resetDrag = false;
         }
         
         var translate : Vector2 = oldPosition - newPosition;
         Camera.main.transform.Translate(translate * Time.deltaTime * dragSpeed);
 //        ScreenClamp();
         
         oldPosition = newPosition;
     }
 
     // If there are two touches on the device...
     if (Input.touchCount == 2)
     {
         // Store both touches.
         var touchZero = Input.GetTouch(0);
         var touchOne = Input.GetTouch(1);
 
         // Find the position in the previous frame of each touch.
         var touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
         var touchOnePrevPos = touchOne.position - touchOne.deltaPosition;
 
         // Find the magnitude of the vector (the distance) between the touches in each frame.
         var prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
         var touchDeltaMag = (touchZero.position - touchOne.position).magnitude;
 
         // Find the difference in the distances between each frame.
         var deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;
 
         // If the camera is orthographic...
         if (Camera.main.isOrthoGraphic)
         {
             // ... change the orthographic size based on the change in distance between the touches.
             Camera.main.orthographicSize += deltaMagnitudeDiff * cameraZoomSpeed;
 
             // Make sure the orthographic size never drops below zero.
             Camera.main.orthographicSize = Mathf.Clamp(Camera.main.orthographicSize, minZoom, maxZoom);
             
 //            ScreenClamp();
         }
     }
     
     ScreenClamp();
 }
 
 function ScreenClamp()
 {
     CalcMinMax();
     Camera.main.transform.position.x = Mathf.Clamp(Camera.main.transform.position.x, min.x, max.x);
     Camera.main.transform.position.y = Mathf.Clamp(Camera.main.transform.position.y, min.y, max.y);
 }
 
 function CalcMinMax()
 {
     currentAR = Camera.main.aspect;
     currentHalfHeight = Camera.main.orthographicSize;
     currentHalfWidth = currentHalfHeight * currentAR; 
     max.y = (originalHalfHeight - currentHalfHeight);
     min.y = -max.y;
     max.x = (originalHalfWidth + currentHalfWidth);
     min.x = -max.x;
 }