ENLARGING LENSES: WHEN YOU ARE READY TO PURCHASE A LENS FOR YOUR ENLARGER BE SURE TO ASK LOTS OF QUESTIONS. IF THEY STATE "NEW" OR LIKE NEW: ASK THE SELLER TO EXAMINE THE LENS UNDER A LOUPE OR MAGNIFYING GLASS,FOR THE SO CALLED "CLEANING MARKS" (THESE ARE ACTUALLY FINE SCRATCHES FROM IMPROPER CLEANING. EVEN WORSE WOULD BE "FUNGUS" THIS IS THE KISS OF DEATH FOR A LENS.COMPANY'S,EVEN ZEISS IN GERMANY WILL NOT ACCEPT THEM,EVEN FOR A ELEMENT REPLACEMENT. THEY SAY THE FUNGUS SPORES WILL BE RELEASED IN THE AIR AND CONTAMINATE THEIR CLEANING ROOM. EVEN IF YOU CAN FIND SOMEONE TO REPLACE THE ELEMENT, IT WILL BE EXPENSIVE & THERE IS NO GUARANTEE IT WILL NOT RETURN.DUST INSIDE A LENS,IS NOT SO MUCH A PROBLEM; AS LONG AS IT IS ONLY A LITTLE.KEEP IN MIND A CLEANING BY A PROFESSIONAL CAN COST $40.00 AND UP.HOPE THIS HAS BEEN A LITTLE HELPFUL AND WILL SAVE YOU TROUBLE AND MONEY.