Lens (optics) divergence of a collimated beam, it does alter the width of the beam. The magnification of such a telescope is given by which is the ratio of the output beam width to the input beam width. Note the sign convention: a telescope with two convex lenses ("f" > 0, "f" > 0) produces a negative magnification, indicating an inverted image. A convex plus a concave lens ("f" > 0 > "f") produces a positive magnification and the image is upright. For further information on simple optical telescopes, see Refracting telescope § Refracting telescope designs. Cylindrical lenses have curvature in only
Cylindrical lens Cylindrical lens A cylindrical lens is a lens which focuses light into a line instead of a point, as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to the intersection of the surface of the lens and a plane tangent to it. The lens compresses the image in the direction perpendicular to this line, and leaves it unaltered in the direction parallel to it (in the tangent plane). In a light sheet microscope, a cylindrical lens is placed in