Wrong exposure with Fuji X-TTL firmware and group metering

edited May 2020 in V6 II Problems
Some time ago I switched my camera system from Canon to the Fujifilm X-H1.
Because I wanted to keep my Canon flashes I bought 1 Cactus V6 II first.
It worked ok but I was limited to the on-camera flash with 1 remote flash and only 1 group.
In order to be more flexible with different flash groups I bought two more Cactus V6 II, so I have one for each of my 3 flashes now.

3 x Cactus V6 II (Firmware FUJ.A.004)
Fujifilm X-H1 (Firmware v2.01)
2 x Canon Speedlite 600EX-RT
1 x Canon Speedlite 580EX II

I also want to use the V6II's Fuji X-TTL firmware "group metering" feature because this way I can control all groups from the X-H1 flash setup menu directly and separately without touching anything else.

My setup:
- one V6II (TX) mounted on the X-H1 with flash on top ( Group A )
- one V6II (RX) with flash ( Group B )
- one V6II (RX) with flash ( Group C )
Fuji only supports 3 groups. Group D is disabled.

I have chosen Group A as the master flash group according to the X-H1 manual:
"Choose a flash group (A, B or C) for the flash mounted on the camera hot shoe when it functions as a master flash controlling remote flash units via FUJIFILM wireless optical flash control..."

So it looks like that with "group metering" enabled the on-camera flash behaves like an own group.

Fuji X-H1 settings:
- A: TTL +-0
- B: TTL +-0
- C: TTL +-0
- TTL Mode: TTL
- Zoom: Auto
- Master: Gr A
- Sync: FP (HSS)
- Angle: Standard
- Channel: Ch1

V6 II settings (TX):
- Sync Mode: Normal HSS
- Exposure Lock: Flash Power Lock
- Multi Flash: Off
- Delay: Off
- Relay: Off
- Group Sequence: Off
- On-Camera TTL: On
Camera & Flash Setup
- Camera System: Fujifilm
- Flash System: Canon
- Flash Profile: Canon 600EX
- Group Metering: On
Power Setup
- Flash Mode: TTL Ratio A:B
- EV Step: 1/3

V6 II settings (RX):
- Delay: Off
- Relay: Off
- Sports Shutter: Off
Camera & Flash Setup
- Flash System: Canon
- Flash Profile: Canon 600EX

What works:
- All 3 flashes are firing
- I can enable and disable the flashes (even the master) from the camera flash setup menu or through the V6II's A/B/C buttons
- I can control the light output on any of the 3 flashes from the camera flash setup menu and it's shown on their displays
- I can control the zoom of the on-camera flash with the zoom lens.
- I can control the zoom of the remote flashes on the TX V6II.

- Whenever I take a picture it's always heavily underexposed.
- Depending on the subject I need FEC values between +2.5 and +5 EV to correct it.
- Without group metering TTL exposure is correct but it's much less comfortable.

Am I doing anything wrong?
Do you know about the problem?
Are there plans to fix it with a new firmware?

Best regards,


Just a suggestion / feature request: The assist light of the flashes is much better than the V6II builtin LED. Please make a configurable option to use the flashes own assist light.

BTW, it took me a huge amount of time to figure out how group metering works. The V6II product manual is awfully outdated, even the respective X-TTL manuals. Some features are described only in the changelog. You (Cactus) could avoid a lot of problems (and sell more devices) by keeping the manuals up to date.
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