On Friday, April 13, 2012 8:11:00 AM UTC-4, Peter Scholz wrote:

When flying a lot in sunny conditions over snow covered areas, you might
want to consider the 90% variant. For all other situations 80% is
sufficient.

Thank you for your comment Peter. I see that Zeiss recommends 90% for flying.

http://www.zeiss.com/4125680F0053A38...256AC00049D720

Can you tell us the color of your irises? Blue eyed people are more photophobic than brown eyed people. Perhaps this explains your preference for 80% lenses?