The Formatt-Hitech 39mm Firecrest ND 2.1 Filter is a solid neutral density filter providing a 7-stop reduction in exposure. This 2.1 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or longer shutter speed than normally required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily.
The design of this filter has been optimized for use with digital sensors and promote nearly flat attenuation of visible, UV, 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 all three spectrums in order to eliminate color casts and ensure cleaner, truer blacks.
Applied to the outside of the Schott Superwite glass construction is a 15-layer Firecrest multi-coating, which helps to minimize reflections and flare in order maintain truer colors and contrast. The multi-coating is also scratch-resistant and hydrophobic to benefit the overall durability of the filter. The filter is set within a 5.5mm-thick SuperSlim aluminum filter ring, which features front threads for stacking additional filters or attaching a lens cap.