The Horseman 4x5 Fresnel Screen is used with the groundglass focusing screen to balance the brightness of the groundglass image.When wide angle lenses are used, this screen’s effects are more obviousThis Fresnel lens is compatible with reflex housings and Horseman models such as the LX, LX-C, LS, HD, and FAOnce the Fresnel is installed on the LE camera, the groundglass is then placed in its original positionThe Fresnel lens is placed in such a way that the rough side faces the ground side of the groundglassRemovable Fresnel screens are ideal for certain applications for which the Snap-On Attachment Kit helps to magnetically fix and remove it from the side of the groundglass