On 2017-04-02 09:10, ąćęłńóśźż wrote:
> Mam lornetkę niemal świecącą na czerwono.

Istnieje hipoteza, że jest to zabieg marketingowy, aby wyglądało ładnie:

Back to those "ruby coated" lenses then. What's up with that? Well, from
what I can tell, ruby coated lenses are pure marketing gimmick. If you
think about it for a minute you should realize that if a bright "ruby"
red light is being reflected from the lens, then that much red light is
not going through it. This results in an image that is
disproportionately green, yellow and blue, giving an overall greenish
cast to the view through the binoculars.

http://boards.straightdope.com/sdmb/showthread.php?t
=153423