Right, the white lenses can be the excellent performers - I myself use 80 mm white lens as a primary macro lens, it works better for me than its black analogue. But the shutter in those is a problem - I was unable to fix a 135 mm white lens because one of the critical parts inside the shutter was too much worn. It should have had a mirror-finished polished surface, but every cycle of shutter was leaving pits on it, and the leafs didn't close as rapidly as needed