There are two main types of lens styles on welding helmets: passive lenses and auto-darkening lenses.
Passive lens helmets are the traditional welding hood. In fact, for those who haven't done much welding, this may be the only kind of helmet that comes to mind. These hoods have a lens that filters out ultraviolet and infrared light with a permanently tinted fixed shade. Since the lens is too dark to see through when the welding arc isn't lit, the wearer will flip the faceplate of the helmet up when putting the welder into position, then flip it back down before striking the arc.
Helmets with auto-darkening lenses take away the need to change the position of the faceplate. The lens will provide a low level of shade when it's inactive (usually #3 or #4). As soon as you strike the arc, sensors will detect the light and darken the lens. Once the arc stops, the lens will lighten again.
Auto-darkening helmets have become the norm, and are generally recognized as a superior choice when compared to passive lens helmets. They also offer a great variety of options.You can choose one from tens of thousands dollars to only dozens of dollars.According to your use and economic capacity,you can definitely choose one that suits you.