I'm busy working out some coverage issues while looking for an older Schneider S ymmar 135mm or 150mm. The 135mm has an image circle of about 190mm and the 150m m an image circle of about 210mm. What I need to know is what the estimated per formance is in lines per mm, about 10 to 20 mm from the edge when stopped down, such as one would encounter during shifts and tilts. I have looked at some test data, but they were done _using_ 4x5 centred and thus not taking it into accoun t. Thanks, Ryan