Anonymous, 13 June 2008 09:00
Close-up filters (often referred to as lenses) are a way of accomplishing macro shots without the expense of a macro lens. These screw-in filters are available in a variety of strengths. Most common are +1, +2, +3, +4 and +10 dioptres. A dioptre is a unit of measurement referring to the optical power of a lens. A +10 filter is ...