The 58mm-Series 7 Step-Up Adapter Ring (Lens to Filter) is a reliable and economical way to use filters. For example, a 49-52mm Step-Up ring would allow you to use 52mm filters on lenses with a 49mm front filter thread size.
Note! There are also Step-Down Rings which allow smaller sized filters to be used on lenses with larger front filter thread sizes. For example, a 52-49mm Step-Down Ring would allow a 49mm filter to be used on a lens with a front filter thread size of 52mm. Care must be taken using Step-Down rings in order to avoid vignetting.