The factor david is talking about is exit pupil. You eye can dialate to a certain size and once that dialation is attained adding more light has no affect. For most people an exit pupil around 7 will work great. A good range is 5-8 according to the techs at Zeiss...but what do they now about glass...<img src=icon_smile_big.gif border=0 align=middle>

&quot;What we do in this life echos an eternity&quot;