It is almost 11 oçlock here now in the evening. Our living room is about 10 m long. I put a circular object of the size you suggested at the distance you suggested from the point of observation (my wife seriously started to doubt my mental health already) and I searched for the distortion you described. I tried very hard, but the circle stayed a perfect circle when I move the circle over the FOV.
There are now two possibiliteis:
-1-my wife is right
-2- the sampe I have for the test does not show the distortion
Gijs van Ginkel
That's very surprising to me, Gijs. As you know it's impossible for a binocular to have no distortion. The designer has to choose between more pincushion with less angular magnification distortion, more AMD with less pincushion or the mixture of the two called "mustache" distortion. One would expect designers to choose the same mix of distortions within a model series and I can't think of any way that distortion could be sample dependent.
If there is essentially no angular magnification distortion in the outer part of the field of your 6.5x32 then it follows that there must be a healthy dose of pincushion distortion in that area because one distortion increases as the other decreases.
If you're willing to try my next suggestion your wife will no longer be in any doubt about your mental health (mine got used to such behaviors a long time ago). If you examine a set of parallel lines or a grid pattern (about 0.5 meters from the binocular) by looking through the front of the binocular instead of through the eyepiece you'll see a pattern like the photo below of window blinds from my 10x42 tests. If the distortion of your 6.5x32 is like the 10x42 I tested it will show the same wavy pattern you see in the photo with barrel distortion increasing out to about 60% of the circle's radius and then reversing and straightening out from there to the edge. If you see a smooth increase in barrel distortion all the way to the edge of the circle that would indicate increasing pincushion all the way to the edge of the FOV when viewing normally through the eyepiece and would match what you saw when you observed the small circle at the field edge.