Hi. Thanks for all of the comments.
I can confirm that the camera was set in Manual mode, HSS was enabled on both the trigger and the flash. I even tested the flash with my Sony to make sure the flash was working correctly, I had no issues using the flash with my Sony.
Originally I used a Hasselblad lens (no leaf shutter) on a Hasselblad to Pentax 645 adapter, so there was no electrical contact/signal to the camera. After reading the comments below I tried using the Pentax-D FA 645 55mm F2.8 and I was finally able to shoot up to 1/4000 of a second!!! I'm really happy that it finally works. I am a bit disappointed that I have to use Pentax lenses. Don't get me wrong I love the Pentax lenses, but I was hoping to use my Hasselblad 10mm F2 for super shallow depth of field.
Thanks to everybody for the comments and suggestions.
---------- Post added 12-20-18 at 03:22 PM ----------
Originally posted by mcgregni The lens type is probably a critical factor and the OP has not even mentioned it. AFAIK the principles are the same for the "Zed" as for the smaller DSLRs ..... You must use an Autofocus lens or an "A" type with the aperture ring set to A, in order to enable HSS with flash.
And as has been referred to also, the ideal camera mode for gaining proper control over things with HSS flash is M mode.
Thanks - you were absolutely correct. It was the lens....
---------- Post added 12-20-18 at 03:25 PM ----------
Originally posted by inkista Sorry. I'm not seeing anything from the Godox side, if the firmware's up-to-date. This is where my being completely unfamiliar with Pentax cameras is not helping.
I haven't a clue.
Only thing I can think of from a quick spelunk through the 645Z manual is whether or not the lens is focal plane or leaf shutter might have an effect. But if you're using a leaf shutter lens, then HSS isn't really something you need... The manual did say something odd about using a leaf shutter lens in [LF], which is that neither of the camera's sync connections (hotshoe or sync port) will work, you have to use the sync port on the lens.
Thanks - I appreciate the help.
---------- Post added 12-20-18 at 03:26 PM ----------
Originally posted by Class A What mode are you using for the 645Z?
If you use "X" mode then the shutter speed will be fixed to 1/125s.
Try manual mode ("M").
Also, try the XPro's "SYNC" button (it's a "soft button" (second from the left) with the label appearing on the LCD screen) to enable HSS on the transmitter. This will probably do the trick.
If you get a shutter speed limitation for modes like "M" then the camera perceives the XPro-P trigger as a flash that is not HSS-capable. Considering that the XPro-P is explicitly sold as being compatible with the 645Z, if you still get a limitation after having tried to switch the XPro-P into HSS mode, I'm left to speculate that there may be a hot-shoe connection issue. You could try cleaning all trigger and hot-shoe contacts.
P.S.: Changing anything on the strobe (including its firmware) won't affect the maximum shutter speed on the 645Z.
P.P.S.: Maybe you are lucky and @inkista will chime in.
Thanks for your help.