Poisson - masks do not interfere with sharpness. Quite to the contrary. I even use masks when making
up precision dupes and internegs to print from. Without exaggeration, I think I can legitimately refer to
myself as one of the world's best Ciba printers, but so what - it's now an obsolete process. But the same masking skills can be adapted to other color media, including RA4 papers, albeit with a steep new
learning curve. And Paul - what in heaven's name makes you think any decent enlarging system has
"lens abberations"? Scanners involve optical components too. And contrast & hue issues can also be
addressed by masking (and have been for decades). If many people prefer to do this kind of work via
scan & PS these days, that's fine with me; but this specifically being an analog forum, I'll advance the
argument that it can still be done in at least as high a quality level using solely darkroom means ...
and it's a helluva lot more fun!