Geometric optics

• Can a Concave Lens Form a Real Image, and What Is Its Magnification?
  A concave lens can form a real image only from converging incident rays; use signed lens distances to find its image and magnification.
• Are Real Images Always Inverted and Virtual Images Always Erect?
  Real images are inverted and virtual images erect for a real object imaged by one standard lens or mirror, but the rule has limits.