// ensure that zoom will not be too small or too big
  Standard_Real coef = Coef;
  if (aViewWidth < coef * Precision::Confusion())
  {
    coef = aViewWidth / Precision::Confusion();
  }
  else if (aViewWidth > coef * 1e12)
  {
    coef = aViewWidth / 1e12;
  }
  if (aViewHeight < coef * Precision::Confusion())
  {
    coef = aViewHeight / Precision::Confusion();
  }
  else if (aViewHeight > coef * 1e12)
  {
    coef = aViewHeight / 1e12;
  }

  aCamera->SetEye (myCamStartOpEye);
  aCamera->SetCenter (myCamStartOpCenter);
  aCamera->SetScale (aCamera->Scale() / Coef);