var fDesc=new Array(); fDesc[0] = "Natural and optical vignetting lead to a gradual transition from a brighter image center to darker corners. At large apertures both phenomena are present and the combined effect is often designated by the term 'illumination falloff'. Vignetting can also give rise to gradual falloff, although the usual connotation is one where it causes an abrupt transition with entirely black image corners.
The Vignetting Reducer will reduce vignetting to minimum."; function tShowHide(id, show) { var s = document.getElementById("desc"); if ((s.innerHTML.length<=212 || show==1) && show!=2) { s.innerHTML = fDesc[id]; if (document.getElementById('m1')) document.getElementById('m1').style.display='none'; if (document.getElementById('m2')) document.getElementById('m2').style.display='none'; if (document.getElementById('more_txt')) document.getElementById('more_txt').style.display='inline'; } else { s.innerHTML = ''; } }