Designed for use with the Canon Drop-In Filter Mount Adapter EF-EOS R, this Canon Drop-In Variable ND Filter A is an intuitive and sleek means for using a variable neutral density filter in conjunction with an adapted lens, especially those lenses lacking traditional filter threads. This variable ND filter is permanently installed within a drop-in holder and has an integrated wheel for adjusting the rotation position to alter the ND effect. The variable ND filter has an ND3-ND500 range, offering 1.5 to 9 stops of adjustment, and creates a darkening of the entire image for photographing with a wider aperture or slower shutter speed than normally required. The degree of density is easily controlled by rotating the filter, helping you to predetermine the additional exposure length required. By increasing your aperture or slowing your exposure time, you are able to control depth of field and convey movement more easily.