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Message: <blockquote data-quote="Binastro" data-source="post: 3286142" data-attributes="member: 111403">Hi Ed,Does someone with an uncorrected squint affect the results, at either end?I suppose a person with a squint has an IPD, IPB even though it may be small or large.Are the IPD, IPB measured at 20ft, 6m or  100m plus?I think this may mean a 1mm difference, but would like an expert view.I have been tested at 6m, 3m and 4.5m.I think reading and distance IPD differ by 3mm??Different measurers will I think vary by 1mm or a bit more.Without explanatory notes it is difficult to know how accurate the studies are over decades.Incidentally, I just read in today's Aeroplane magazine that early Chipmunk trainers did not recover from spins. My flight a bit later thankfully had the  modified rudder. A cadet broke his leg even usung a parachute.</blockquote>