Edited sentence: For example, a very dark neutral density filter can be used (such as the Hoya ND400) which passes a very small amount of visible light compared to the near-infrared it allows through.This technique mirrors the methods used by infrared film photographers where black and white infrared film was often used with a deep red filter rather than a visually opaque one.While it is common to use a filter that blocks almost all visible light, the wavelength sensitivity of a digital camera without internal infrared blocking is such that a variety of artistic results can be obtained with more conventional filtration.Wider filtration is however likely to reduce other infrared artefacts such as haze penetration and darkened skies.Wider filtration permits an SLR viewfinder to be used and also passes more varied color information to the sensor without necessarily reducing the Wood effect