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Message: <blockquote data-quote="Surveyor" data-source="post: 3539092" data-attributes="member: 50720">David, Henry;Maybe just adding to the confusion. I have attached Tables 1 & 2 from ISO 14133-2 for high performance instruments and an ISO figure about convergence/divergence that I found somewhere. Note the ISO definition is bassackwards of the rest of the world. There definition is for emergent beams for the eyepieces (image space), not referenced to the optical visual axis.You will note that table one is based on the emergent beams (image space/apparent angle) so the power is applied. Also, this method has a means for reducing collimation error as power is increased. Example: for convergence (20’) at 6x the allowable error is 3.33’ in object space and at 15x the allowable error is 1.33’ in object space. This is maximum over the full IPD range.Table 2 is the defined resolution in object space (real angle in arc seconds). I have not seen the new specification David referred to.</blockquote>