Here are the sobering numbers.
"There are strong stories surrounding this viewer on the internet, among other things. It has been claimed for a long time that the
viewer has a light transmission of 95%. Our measurements were unable to confirm this. The
highest value of transmitted light for daylight viewing in the spectral region where the
eye is optimally sensitive (550-560 nm) is approximately 85% and that is considerably less than the claimed
95%. It should be noted that at a light transmission of 85% the image brightness is noticeable
is less than with a light transmission of 95%."
Andreas