advantages in the case of large magnification values and small magnifier models. What is a Fresnel lens? The Fresnel lens refracts the light like a conventional lens, but does not consist of a smooth, curved [...] value, but loses some of its image quality. What is the difference between Fresnel lenses and diffractive lenses? The Fresnel lens refracts light. Diffractive lenses defract light. [...] Vario Plus system and use it at the same time? No. For technical reasons, it cannot be used during the 4-hour charging period. What is a dioptre? A dioptre (dpt) is the unit of measurement of the optical power