These waterhouse goodies were related to the reproduction of halftone dots, which needed to be crisp and might have been slightly affected
otherwise at different magnification ratios. You'd have to talk to someone from back in the traditional printing industry days, unless someone
here has that background. I use these lenses in the darkroom, though it would be nice to have shutters for a few of them too, for view camera use. They're optically marvelous. The multi-bladed apertures are wonderful too, but don't expect a pleasant "bokeh" from these tack sharp lenses - it's more the double-lined effect. I've contemplated how to screw-up the optics with some kind of softening diffuser in one of those little inserts, just for the fun of it. I'm not really a soft-focus type, however.