The Beseler lenses were not top-notch lenses, just adapted lesser f/9 graphics lenses more common found on copy "stat" cameras. And the notion of a "heavy duty" chassis? Well, yeah, by comparison to some previous Beseler options, but certainly nothing real commercial duty. Those Beseler conversions are adequate for, say, making a basic 16X20 print from 8x10 black and white film. But it's not a suitable system for anything bigger. I've seen em in use. You'd get a lot more versatility and precision by converting a Durst 138 5X7 chassis to an 8x10 head.