people in Europe use their telescopic sights at dusk, dawn and at night, when their pupils are larger. Thus the daytime exit pupil of about 3 to 4 mm is not a universally desirable standard. For comfort, ease of use, and flexibility in applications, larger telescopic sights with larger exit pupils are satisfying choices even if their capability is not fully used by day. Eye relief – Eye relief is the distance from the rear eyepiece lens to the exit pupil or eye point. It is the optimal distance the observer must position their eye behind the eyepiece to see a non-vignetted image. The longer the focal length of the eyepiece, the greater the eye relief. Typical telescopic sights may have eye relief ranging from to over , but telescopic sights intended for scout rifles or handguns need much longer eye relief to present a non-vignetted image. Telescopic sights with relatively long eye relief are favorable to avoid periorbital lacerations and eye injuries caused by recoil-induced collision with the metal eyepiece (colloquially known as a "scope bite"), especially in instances where it is difficult to keep the stock steady. Eye relief is important for eyeglasses wearers, as the presence of an eyeglass in front of the eye shortens the available physical space before colliding with the eyepiece, so a longer eye relief is necessitated. Optical coatings Because a typical telescopic sight has several optical elements with special characteristics and several air-to-glass surfaces, telescopic sight manufacturers use different types of optical coatings for technical reasons and to improve the image they produce. Lens coatings can increase light transmission, minimize reflections, repel water and grease and even protect the lens from scratches. Manufacturers often have their own designations for their lens coatings. Anti-reflective Anti-reflective coatings reduce light lost at every optical surface through reflection at each surface. Reducing reflection via anti-reflective coatings also reduces the amount of "lost" light present inside the telescopic sight which would otherwise make the image appear hazy (low contrast). A telescopic sight with good optical coatings may yield a brighter image than uncoated telescopic sights with a larger objective lens, on account of superior light transmission through the assembly. The first transparent interference-based coating Transparentbelag (T) used by Zeiss was invented in 1935 by Olexander Smakula. A classic lens-coating material is magnesium fluoride, which reduces reflected light from 5% to 1%. Modern lens coatings consist of complex