while a simple concave mirror projection does not? Hi, I'm really not sure where does this question go, but perhaps this is as good a place as any... If not, then I would appreciate a referring to the right place. So, I have encountered this nifty, decades old, illusion created by combining two concave mirrors : http://dev.physicslab.org/Document.aspx?doctype=3&filename=GeometricOptics_RealImages.xml I understand how it works and I kinda assumed that all mirrors which have a certain focal point would act similarly so their image projection would look like the object is actually there. I have googled a bit (youtubed actually ) and have encountered some videos on the matter: None comes even close to the quality of said illusion, and I wonder why is that? Same goes for those experiments with a lens (a long metallic rack in which you move a needle closer and farther from a focusing lens). In theory it should all work, but... Thank you very much!