I utterly hated that Compur 3 shutter. Unlike a Copal, even the high speeds were spot on. But there was no T setting, and the damn thing had a distinct buzzy vibration too it (every example I've tested). This actually affected 4x5 field camera sharpness, though not my more solid 8X10. Then the contrast was just toooo much for my outdoor chrome work of the era. In the long run, I figured out that the single-coated Kern in Copal was better for my personal needs. But I have never encountered another lens with the color purity snap and sheer microtonality in b&w work quite like that MC Kern.