How much difference between ideal and actual adaptor size do you need to see an actual difference? I have a Kiwifotos AP209 Sony A-mount to Mu43 adaptor and from testing with two lenses and two bodies, it has a definite macro bias - lenses can focus closer than stated on the focusing ring, and they don't focus anywhere near infinity :-( Research suggests FFD for A-mount is 44.50mm and Mu43 is 19.25mm, giving a difference of 25.25mm, and that should be the size of the adaptor, right? I have measured my AP209 at 26.15mm, a 3.4% error: It doesn't sound much but the effect on focusing seems to be pretty dramatic. With a 50mm f1.8 (SAL50F18) I can't focus beyond about 6 metres. With a SAL-1870 [which isn't worth bothering to adapt, BTW] it won't even focus beyond a metre at the wide end, 20m at the long end. Can anybody give me a measurement of a working A-mount adaptor?