First, thanks for your help in advance.
My Magnifax is not model "4a", it's the older one called model "4" (without 'a' letter). And I think the condensers lens have different numbers between models range because my condenser nš1 is the largest I think. Here is a photo I have taken:
Photo 2013-03-18 11.05.50 p.m..jpg
Yesterday I did some 6x6 and 35mm with this condenser in 8x10 and 4x6 paper on both formats and I don't notice any vignetting in final prints if it's what supposed to happen. Can you confirm please ?