TELESCOPE D'ASTROPHOTOGRAPHIE NP101is / NP101is IMAGING SYSTEM SCOPE
The NP101 has a focal length of 540mm and an aperture of 4", for a focal ratio of f/5.4
It is a specialized imaging system scope, with a redesigned 4-element optical system that minimize vignetting in formats up to 50mm diagonal. For these large chips an optional field corrector was developed so the corners of the newly brightened edges would virtually be as perfect as the center of the field.
The Focusmate 6:1 planetary ball type reduction focuser provides extremely sensitive focus adjustment, measurable with the optional Digital Micrometer Kit to better than 1/10,000".