i am using a master linh.tech. with a new apo-symmar 180/5.6
since using this lens i am noticing a very small vignetting on the four corner of the chromes. please note that the pictures was taken with no swing,tilt or any other movement . the subjects are beetween 3ft and 8ft. the films holders are several differents new lisco. could any one help me to find what cause this problem?
many thanks. luc