Back to Main FAQs Q. If I use an auto darkening filter equipped welding helmet, will I see "flash" in the time it takes the lens to switch from light to dark? A: No, most if not all brands of ADF switch from light to dark many times faster than the international standards require and the human eye can see. In some of the old slower models, the wearer occasionally saw a split second of bright light but their eyes were still protected from radiation by an interference filter. Updated: June 2007.