The Tiffen 67-72mm Step-Up Ring is a reliable and economical way to use filters. For example, a 49-52mm Step-Up ring would allow you to use 52 mm filters on lenses with a 49 mm front filter thread size.
Note! Tiffen also produces Step-Down Rings which allow smaller sized filters to be used on lenses with larger front filter thread sizes. For example, a 52-49 mm Step-Down Ring would allow a 49 mm filter to be used on a lens with a front filter thread size of 52 mm. Care must be taken using Step-Down rings in order to avoid vignetting.