Distorted sprites in fullscreen mode

I am trying to get pixel perfect 2D on the screen and I have made a script that is attached to the scene that sets the orthographicSize of the main camera like this:

Code (CSharp):

1. void Start () {
2.     float pixelToUnits = 100;
3.     float cameraSize = (Screen.height / 2) / pixelToUnits;
4.     Camera.main.orthographic = true;
5.     Camera.main.orthographicSize = cameraSize;
6. }

If I run this in the editor it all looks good and it also looks good on my iPad, but in some resolutions (e.g. 800/600) my sprites gets stretched wider. I think this is because this resolution has a different aspect ration than my monitor (monitor native res is 1920x1200 that gives 1.6 and the resolution 800x600 gives 1.33), am I right?

Is there a good way to fix this so my sprites never gets stretched in any resolution?