How does spherical aberration cause an image to appear when the object is placed at the focus??? In theory, when the object is placed at the focus, no image should appear but when i did an experiment with a concave mirror and a candle, image did appear. But the image was very very far away from the focus but still on the image side. Does this have anything to do with spherical aberration? or the thickness of the candle? because in theory, ur only talking about a single line and the candle posesses a thickness... maybe that has something to do with the image appearing???