Hi to all,

I have a question I'm hoping you experts can answer, in the UK we seem to have huge lacking of any optical forum boards......
In my practice, we are restricted to dispensing blue tints any darker than 72%LTF/ 18% absorption, my question is.....

Where the figure of 72%LTF has been calculated from, I'm assuming an equation has been done at some point to come to that figure, but i cant find it anywhere.........

And also what specific impact does it have on traffic light recognition.

Many thanks to all you clever people who answer.