Motivated by Holger's alternative suggestions to explain Tobias' complaint of flare and glare, I once again took a dive into the Noctivid's internals and I found this (see my picture - an original work of art). Under certain conditions with strong sun light entering the binocular in a specific angle, these rainbows can be found at the 5 and 7 o'çlock position in the viewing circle. And also but with more effort at 11 and 1 o'çlock.
This may look alarming, especially regarding my beautiful drawing, but note that these phenomena can only be seen when one looks from the eyelens into the binocular from a rather awkward, completely unusual angle. When looking through the binocular, as we all are used to do by nature, these rainbows don't show up, they're nicely out of sight.
I then turned the binoculars upside down and searched for the colors again. Nope. When the Noctivid is used upside down there are no rainbows to be seen.
Then I tried to ascertain if I could detect changes in flare and glare between the usual and upside down type of use. My verdict is: no. I don't see any differences in flare, glare or contrast. Which leads me to the conclusion that the 'rainbows' do not have an effect on the Noctivid's optical performance.
Renze