Modern auto-darkening welding helmets with very fast lens reaction times are definite improvements over the older and heavier leather helmets with fixed lenses. However, there are still some issues that need to be addressed. One common complaint among experienced welders is that the act of tipping the visor into place forces the welding tool itself out of position. This often requires the welder to reposition the tool on the fly, and this can result in a poorer weld. Short, tack welding jobs are also harder to perform if the visor needs to be raised and lowered constantly for repositioning.