hi alberic.
thanks for your quick response.
i have read your writings many times.
after some search and watching the following videos all microscopes having optional external darkening filters.
still i have a lot of questions, why not ?
https://www.youtube.com/watch?v=te9DNO76b08&list=PLts8iuZLOafHwFHA9-ZCX0RTSAUkYQ7TC
http://www.sstmicrowelding.com/en/products/spot-tig
MICRO WELDING (TIG V-01 JAPAN)
after second 0.25 Como Soldar ouro, prata, platina, aço inox
thanks for the time devoted !