I like this thread. So, let me copy
https://www.pentaxforums.com/forums/601354-post3422.html over here
In an attempt to sort out the possibilities with regard to the flash sync time, I computed the respective widths between shutter curtains:
Width between shutter curtains (vertical shutter):
K20D: APS-C, 1/4000, 1/180X: 0.70 mm
K-7 A: APS-C, 1/8000, 1/250X: 0.49 mm
K-7 B: APS-C, 1/8000, 1/180X: 0.35 mm
MX: VF, 1/1000, 1/60X: 1.44 mm
LX: VF, 1/2000, 1/75X: 0.9 mm
PZ-10: VF, 1/2000, 1/100X: 1.2 mm
PZ-1: VF, 1/8000, 1/250X: 0.75 mm
So, even if RH is correct in his assumptions, a 1/180X on the K-7 means an extraordinarily small slit. Let's call it
"precision slit". Not necessarily a cheap thing ...