This 2- to 5-stop, 77mm Peter McKinnon Signature Edition II Variable ND Filter from PolarPro is designed for lenses with 77mm front filter threads and provides an exposure reduction of 2- to 5 stops. The 0.6 to 1.5 density creates a darkening of the entire image, allowing a wider aperture or slower shutter speed without overexposing your image. The degree of density is easily controlled by rotating the front filter ring, helping to predetermine the additional exposure length required. By slowing the exposure time, you convey movement or increase the blur. By increasing the aperture, the image depth of field can be more easily controlled. For easier, repeatable control over density settings, the front ring features a numbered scale of the stop values, and it also features haptic feedback to feel a click when reaching a number without the need to look at the ring. The ring features side knurling for a secure grip, enabling fast and precise positioning, and it is designed to prevent any rotation beyond the stop values etched on it.