I'm a fairly recent convert to MF - about 6-7 months. I have been using a Pentax 645N with a 75mm prime and a 200mm prime. Mostly I am shooting slower films (50 - 100 ISO) with tripod striving for very sharp, detailed, low grain negatives. I have been very pleased with the ability of these lenses to deliver just that. I am considering an 80-160mm (FA) zoom to fill in all the focal lengths between the primes, and for portrait work. Will there be a discernible difference in sharpness with the zoom as compared to the primes?