Kepler
The telescopic effect can be achieved with different combinations of lenses and mirrors. As early as 1611, in his Dioptrice, Johannes Kepler had shown that a telescope could also be made by combining a convex objective and a convex ocular. He pointed out that such a combination would produce an inverted image but showed that the addition of yet a third convex lens would make the image erect again. This suggestion was not immediately taken up by astronomers, however, and it was not until Christoph Scheiner published his Rosa Ursina in 1630 that this form of telescope began to spread.