Alex I should start another thread after this .
There was a time when the numbers from various optical tests were the ultimate criterion of what I though real !
Mirrors with top number tests were sort after ..
Then I was shocked to read this article from Carl Zambuto site .
https://zambutomirrors.com/zambutoopticalce.html
My thoughts of the only True simple way to test a mirror will need it's own thread .
Including the secondary .
Bobby.