Originally posted by BarryE 1) Can I trigger Cactus flash units from another manufacturers trigger? I'm guessing not. So onto the next part.
That would be my guess as well.
Originally posted by BarryE 2) I work in manual, triggering multiple flashes from my K-1, I assume I could use a Godox trigger to do this?
The short answer is yes, though you would be triggering Godox devices.
Originally posted by BarryE 3) The Godox TT600 flash units seem to be popular. I assume I would be able to replace my Cactus flashes with these (cheaper than Cactus) TT600s and trigger then from the Godox trigger, in much the same way that I'm using my Cactus gear?
Working in full manual the TT600s would be fully controllable from a Godox controller, though only for their basic feature set (intensity, zoom, and multi) plus HSS with if the controller supports Pentax. If you want Pentax TTL, you can control several different Godox flash from a Pentax flavor controller. The determinant for TTL, HSS, or trailing curtain sync is the shared feature sets between controller and flash units.
Originally posted by BarryE Now as I write this I'm seeing another mistake I made sticking with Cactus. Am I correct in thinking the Pentax compatible Godox trigger would trigger any of their flash and strobe units?
You are correct. Consider too that if one needs a compact flash to go with the new K-3iii, a Godox TT350P can also do wireless control of several other Godox flash. Scary isn't it?
Here is a wrench thrown into the mix. I really like Godox and would likely be looking that direction except that I currently am fully manual in the Yongnuo system and it meets my needs quite nicely with a mix of a couple of YN560III speedlights, a YN560TXII controller, and a couple of RF603 II TX/RX triggers. My total investment is about $150 USD total (caught some good sales). Prices have gone up, but for another $150 I can add two more YN560III and deploy a mix of four remotely controlled speedlights and two other flash using local control, but also supporting auto. I can also have a wired P-TTL flash in the same mix.
As much fun as it would be to dump Yongnuo and go Godox, as long as I can work with what I have, I am quite content.
Steve