The Tiffen 77mm IR Variable Neutral Density Filter is a solid variable neutral density filter providing an exposure reduction of approximately 2 to 8 stops. The 0.6 to 2.4 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. The degree of density is easily controlled by rotating the front filter ring, helping you to predetermine the additional exposure length required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. For repeatable control over density settings, the front ring is also visually demarcated with index dots for quickly returning to desired density placements.
This filter has been optimized for use with digital sensors and incorporates an IR blocking layer, which attenuates both visible and infrared light. Due to imaging sensors' greater susceptibility to infrared light, compared to traditional film, color casts can occur when photographing darker subjects that require increased exposure times. This filter provides a high level of neutrality across both spectrums in order to eliminate color casts and ensure cleaner, truer blacks.
This filter is made using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass, grinding flat to a tolerance of 1/10,000th of an inch, and mounting within an aluminum filter ring. The larger front diameter of the filter measures 88mm, helping to reduce the likelihood of vignetting with wide-angle lenses, and does not feature front threads.