Adaptor-rings are the first step in determining the system you should use. They are available in various diameters. First, refer to the lens with the biggest diameter you own. The diameter of a lens is either written on the front or side of the lens itself, in the cap, or in the lens user's manual. Once you know what is the diameter of your lens, refer to the chart below to chose the system that will fit your needs.
C Compatible with CREATIVE filter-holder
E Compatible with EVO filter-holder
* If used with a wide-angle lens of this diameter, Cokin advises upgrading to a bigger system to prevent vignetting issues that may occur.
(FF) If used with a lens under 28mm on a full frame, you may need to remove one or two slots from the filter-holder to prevent vignetting, or to upgrade to a bigger system.