No lah, I don't think I have 8mm dark-adapted eye pupil... haha!You have 8mm entrance pupil diameter??? no wonder you can see the horsehead nebula using direct vision while the rest of us can only use averted vision on the f/5 scope
as the S&T Sep 05 article "Special Report - Night Myopia" states that " ... an amatuer astronomer whose dark-adapted pupils span 6millimeters typically will experience a half diopter of night myopia, while the rare stargazer whose pupils can open up to as wide as 8mm may experience a 1.5-diopter effect - though both numbers vary widely within the human population...." My increase in power is only -1 diopter, but I rather not have night myopia!Also, I didn't realised at first that the rest of us (experienced & sharp observers like Elton, Arief & Yang Beng) only saw the Horsehead Nebula with averted vision; no wonder it was so easy for me to find it at my first attempt with direct-vision!
So yes, guys, we have all got to try and check our dark-adapted eye pupil at the next Mersing trip at the start of March! I will bring the allen keys to do the other type of test.