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Message: <blockquote data-quote="Binastro" data-source="post: 3569420" data-attributes="member: 111403">Thanks Ron.What I mean is that some eyepieces are designed to be like high quality macro lenses, having less than 1% barrel or pincushion distortion. Although near the field edge these eyepieces suddenly have severe changes in magnification. Say the 7 element Russian eyepieces on 7x30 and 10x42? I am not talking about other aberrations only rectilinear.With regard to hand holding, the increase in field size is because of slight hand movement so that one sees slightly past the stationary field edge. Because we remember views for fractions of a second two stars can be seen with just slightly larger separations than possible on a tripod.If the IPD is deliberately set slightly wrong one can increase field size horizontally.High quality binoculars usually have both tubes overlapping almost exactly on the stars. Less than 1% overlap. Cheap binoculars such as 6x18 Chinese can have massive overlaps even though, or because, they are more or less aligned to cope with poor mechanical parallelism.Can you supply a simple minimalist drawing of the set up you describe in post 50, thumbnails. What sort of focal length lenses. Simple achromats or photo lenses?I am not good with computers.</blockquote>