Quote: Hmm, I just tried to use my external manual flash with no lens attached. I held a k-moun lens in front of the sensor to simulate the condition of using an adapter. And I could NOT get the external flash to fire at any shutter speed. I used the same setting of Flash OFF and also to disable the internal flash when retracted. This settings that will let me fire when the 01 prime lens is attached do NOT work when there's no lens attached.
I came to the same conclusion yesterday. Regardless of the electronic shutter custom function, my skyports or pws would not fire at any speed beyond 1/250 with the standard prime 01. The camera itself turns off the external shoe beyond 1/250. I believe the 1/250 limit is an artificial limitation imposed via firmware as the standard prime's leaf shutter should easily sync beyond that.
I don't have PTTL flashes, so without a Q compatible lens mounted which would be the case if I adapted a lens, I get no triggering capability at all.
Did a quick triggering test yesterday at 1/250 @ f8 with nd filter on . This is the equivalent of a 1/250 @ f16.