Safety first: your retina has no pain sensors so the only thing that can prevent eye damage is your brain. Here’s what to know. Filters must be OD 5 (Optical Density 5, 0.00001 transmittance or 16.6 stops), OD 6 (20 stops) or welders glass shade 14 if you are going to look through them. OD 4 (13 stop) filters…