This part of ISO 14490 specifies the test methods for the determination of the following basic characteristics of telescopic systems and observational telescopic instruments: — angular magnification (see Clause 4); — entrance pupil diameter (see Clause 5); — exit pupil diameter and eye relief (see Clause 6); — angular field of view in the object space (see Clause 7); — angular field of view in the image space (see Clause 8); — angular field of view in the object space for spectacle wearers (see Clause 9); — collimation of the bundle of rays emergent from the eyepiece (see Clause 10); — image rotation (see Clause 11); — closest distance of observation (see Clause 12).