Originally posted by emsee If I use a Canon compatible flash (Godox), ...
You've already been told that no, a Godox -C speedlight will not work in TTL/HSS, etc. on a Pentax hotshoe. And this is for the simple reason that the Canon electronic flash signalling protocol used by Canon for TTL is different than that of Pentax for P-TTL, but on top of that, the pins on the foot won't match the contacts on the flash hotshoe:
So, signals, other than the one for sync (that big contact in the center, which is part of the ISO standard, and to which all digital camera hotshoes now conform), won't even be exchanged. This is also the reason for the RF-60x (and Godox TT600/V850II) not working in TTL/HSS on the hotshoe or being able to be a TTL/HSS radio master. They only have that single sync pin, so can't receive any TTL/HSS commands via the foot, so can't pass them along as a radio transmitter. The only thing you can tell a single-pin flash to do through the foot is when to fire.
However. Godox is very likely to eventually roll out TTL/HSS speedlights
for Pentax. They've already announced the
TT350-P. This is a good indication they'll follow that up with TT685-P, V860II-P, and V350-P releases. (All the non-Canon/Nikon "flavors" of Godox speedlights had the TT350 introduced as the first model for that flavor).
And in the Godox system, all the speedlights have transceivers in them, so they can be both an on-camera speedlight as well as a radio transmitter for other off-camera Godox flashes.
Quote: ... how does the X-TTL work? Does it work on-camera (mounted on top of V60II)?
How the cross-brand TTL capability in the Godox system works is that any of the built-in radio transceivers or receivers in the Godox lights in the 2.4GHz X system can automatically switch among all of the supported TTL/HSS schemes.
Provided the flash has been firmware upgraded to do so. At this time, in the Godox system, only the AD600 strobes have had these firmware upgrade published. Over time, we should eventually see the AD200, AD360II, TT685, V860II, TT350, and V350 models receive similar firmware updates. For the -O/-F rollout, it took about three months from the time of the release of the X1T units for all the firmware upgrades to be rolled out. With -S gear, it was about a year. So it could be a while.
Without the firmware updates, you should have remote power control and
possibly HSS. The TT600 and AD200, but not the AD360II, are performing HSS with the XPro-P based on
this report.
The Godox X1R receivers are NOT like the Cactus V6II units;
they do not support cross-brand TTL, and will only do TTL in their dedicated flavor. And right now, they only come in the -C, -N, and -S flavors. So, adding legacy P-TTL flashes into a Godox scheme, at this time, will not work like it will with the Cactus V6II system. You have to get Godox lights with the built-in triggers. But those lights also include the AD200 and AD360II bare bulb flashes, the AD600/AD600 Pro battery-powered monolights, and the QTII, QSII, GSII, DPII, and SKII series of AC-powered monolights.
But whatever goes on the camera hotshoe as your transmitter unit has to be in the -P flavor, so that the footpins and hotshoe contacts match and the camera TTL/HSS signalling can be interpreted by the unit. Off-camera speedlights, however, can be Godox flashes in any of the six supported "flavors" (Canon, Nikon, Sony, Fuji, Olympus/Panasonic, Pentax).
I currently use a TT685-C (Canon) in TTL/HSS with remote power control with an XPro-C transmitter on my Canon 5DMkII, an XPro-F on my Fuji X100T, and an XPro-O on my Panasonic GX-7. I don't need to get a new light for each camera system. And the flash is capable of switching between systems even in the same shoot, so long as all the transmitters are set for a multi-user scenario.