LensSym is a thin lens simulator. You can give it the height and distance of a real object from the lens and it will calculate the height and distance of the real or virtual image.
Below are the main features:
-Calculates height of real or virtual image
-Can move the lens to a new position
-Can change the focal point
-Can change the height and position of real object
-Change the x and y scale for better viewing
This is a fun application for anybody interested in lenses.