If you are invariably using the same welding technological advance on the same material, a fixed shade lens is sufficient. But, most welders are using a variety of materials and welding a number of different applications, your best bet is a variable shade lens, which will adjust to the comfort darkness for your particular process. For example, when you are GTAW welding at lower current, you may need to lighten up the lens to see what you are doing - a variable shade lens will permit this while a fixed shade will not.

In most cases, it is a personal preferences choice and what is most convenient to the operator. But, one thing to watch out for is getting "flashed" with battery-operated welding helmet. These welding helmets offer a feature that will automatically turn off the battery after the helment has been sitting idle. If the worker isn't careful, he could get arc flash thinking that his helmet is still dark. Solar powered welding helmets also offers the convenience of not having to worry about changing batteries.

Welding arcs emit harmful UltraViolet and InfraRed wavelengths of light. Unprotected from IR and UV, discomfort and both eye damage can occur. High-quality auto-darkening helmets provide InfraRed and UltraViolet protection even when the welding helment is not activated, you are always protected. But, for maximum comfort, select a high quality welding helmet that has a response darkening time of 0.4 millisecond. Less than a millisecond is not perceivable by the human eye and will provide the most comfort.