If you have a filter drawer you ought to be able to change the filters for spilt contrast printing out any problems . I have older Dupont and Kodak filter with a filter holder for below the lens as well as new 6X6 Iflord filters that I just put in the variable condenser housing of my D3 above the lens, the below filters are more likely to show dust. My below the lens filter holder is also too small for some of my long lens such as a 135 or 162mm.