NB23 and Docchilie are correct: below lens filters work fine with the focomat 1c without too much fuss about dust. I bought a very early model a few years ago for the equivalent of less than 50 USD to use alongside my Focomat V35 (lamps for the 1c are much easier to get here than those for the V35). I use the 1c when I want black borders -- it does them perfectly. The glass of the condensor and the Focotar 50 mm f4.5 lens as well as the anti-Newton glass is excellent, and the autofocus is spot-on after I adjusted it according to the instructions. I use the 1c when I want black borders. Print quality between the two enlargers is practically identical.