what can you say about images formed by a concave lens?
However, for a lens, a positive image distance implies that the image is located on the opposite side as the object. Virtual images are formed by concave lenses or by placing an object inside the focal length of a convex lens. The ray-tracing exercise is repeated for the case of a virtual image. In this case the virtual image is upright and shrunken. The same formula for the image and object distances used above applies again here.