Photodana :
"It is a riddle to me that Key light/Fill light was NOT concept incorporated in off camera flash technology" ClassA : "Perhaps @mcgregni, who wrote the book on P-TTL, can tell you otherwise. It seems to me that Pentax's incredibly simple contrast mode may do what you want. Personally, though, I wouldn't want to rely on such a fixed approach"
Yes indeed, the Pentax Wireless system includes a Ratio setting control, which can function with up to two off camera P-TTL slaves and the On-Camera 'Master' unit. As ClassA says, this is simple, giving a 1:2 / 1:3 / 2:3 set of ratio possibilities.
In the absence of any meaningful label (and description) of this functionality in the Pentax Flash Manuals, for my Guides I have created the term "Wireless Lighting Ratios". This is all detailed on Pages 70-72 of the Guide, within the "Wireless (Off-Camera) Operations section. (Download from the link below my Signature under my post, should this be of interest).
As Clackers has already said (and Class A has also referred to in the past), it is a fairly simple matter to reproduce exact "ratios" via either flash compensations or Manual power level settings (depending on the chosen flash operating mode).
Bear in mind also that the Pentax "Wireless Lighting Ratios" do not apply to, and are not implemented by, the Cactus X-TTL radio system. There also is no Ratio control built into the Pentax version of this firmware. To use the feature fully you need two Pentax "FGZ" flashes and a Built-In camera flash that includes the Wireless 'Master' capability. You can also create a simpler two flash ratio (eg 1:3 / 2:3) with a combination of one on camera 'master' flash and one slave. Finally, I do not believe that the Metz flashes include these Ratio settings for wireless working.
Also, one further word of caution ..... the use of Auto ("A") mode with the flash on top of a Cactus V6II may be unproven also . Bear in mind that the communication protocol for "TTL Passthrough" is P-TTL ..... Auto-Thyristor mode on the Pentax flashes shuts off any data communications through the hotshoe (the flash becomes isolated completely from the camera in terms of settings and flash metering). So I don't think it is yet known for sure whether TTL Passthrough will actually work with a flash set to Auto Thyristor mode .....
If the V6II sends a trigger signal through to the top shoe regardless then all may be well, but I'm not sure about this as I have only operated before using TTL Passthrough and a flash set to P-TTL mode.
Originally posted by Class A @mcgregni
Have you tried using the AF-540FGZ II on top of the V6II (with the settings you posted) without activating TTL pass-through? What happens then?
I've now tried this also, with TTL Passthrough off (both via the Menu setting and using a long press of the Menu button), and it makes no difference to the behaviour of the flash on top of the V6II ..... even with TTL Passthrough off, the flash zoom still responds to lens zooming movements, but it will not fire.
I would have expected the zooming to have stopped surely, because this is part of the TTL communications that should be activated by TTL Passthrough mode. This suggests to me that there is something wrong with this aspect of the PEN.A.001 firmware.