public class SetCameraProjectionMatrix : MonoBehaviour
{
    public float fieldOfViewOverride = 60.0f;

    void Start()
    {
        Camera cam = GetComponent<Camera>();
        Debug.AssertFormat(cam != null, "No {0} component on game object named {1} as expected.", typeof(Camera), gameObject.name);
        cam.projectionMatrix = Matrix4x4.Perspective(fieldOfViewOverride, cam.aspect, cam.nearClipPlane, cam.farClipPlane);
    }
}