The Converter H 1.7x increases the focal length of a lens by a factor of 1.7x. It features the same outstanding optical and mechanical quality as the elements in the Hasselblad H-lens series. All the glass-to-air surfaces have a multi-layer coating to reduce internal reflections and increase the efficiency of the optical system. The aperture reduction is -1.5 stops.The Converter H 1.7x can only be used together with Hasselblad H lenses. Attempts to attach any other type of lens may cause damage.