I just purchased a Weston Master II meter and it came with a plastic invercone. Could someone explain how to get it to fit ( I think it needs to be filed down). Can it be used on both scales ( 25-1600 and 0.2-50 )? My understanding is that it is used when you want to use the meter as an incident light meter, so you would point the meter at the camera ). Thanks, Bob ( Meter is Sangamo Weston, model S141/ 735), made in England. )