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).