User Tools

Site Tools


Cactus v6II remote radio wireless TTL flash with the Olympus OM-D cameras


  • currently, neither Olympus nor Panasonic have radio TTL remote flash support for their Micro Four Thirds system
  • they currently only offer remote TTL flash RC mode with the Olympus OM-D cameras which is an optical based remote control system
  • thus for radio control of remote flashes we need to look at third party solutions, this page will explain how to use the Cactus V6 II system to enable cross-platform radio remote flash control.

Cactus v6 II X-TTL system

  • Cactus V6 II system will now support cross-platform radio wireless TTL flash via a free firmware update announced March 2017
  • for remote TTL, you must install camera system specific firmware on the cactus V6II that will attach to the camera (if you don't need TTL, then there is a separate multi-syem firmware that will work for any of these brand cameras)
  • will be able to use Canon, Olympus and other TTL flash units to work in either on-camera TTL or via radio remote TTL mode on various camera models, initially, Sigma, Sony and Fujifilm cameras, and then Micro Four Thirds Panasonic and Olympus cameras as well as Canon, Nikon, and Pentax cameras.
  • they will also allow remote control of power output and automatic zoom as well as Super FP/HSS mode, low output option (less than 1/128th to allow for ultra brief exposures) and Power Sync (presumably, similar to HyperSync)
  • two new types of unique TTL flash exposure Locks:
    • Flash Compensate
      • store a desired flash exposure that will automatically adjust according to changes in camera settings. Gone is the ever-changing flash exposures between each TTL metering.
    • Flash Power Lock
      • lock flash power output after a desired TTL exposure is achieved. Perfect for consistency in repeat shooting. Wireless TTL functions
  • a few gotchas:
    • on Nikon, Fuji, Sigma, Sony, Olympus and Panasonic cameras, the only flashes you can use for cross-TTL are Canon, Nikon, Sigma, Fuji, Olympus and Panasonic system flashes and not all flashes are compatible but you may be able to create a custom profile for your flash via your computer (can store up to 10 custom flash profiles)
    • on Canon cameras, the only flashes that will work in remote TTL mode are Canon system flashes
    • on Pentax cameras the only flashes that will work in remote TTL mode are Pentax system flashes
    • there is a different Cactus V6II model for Sony Cameras and Sony mount flashes but you can use your Canon or Olympus flash on a standard version and triggered by a Sony a7 with a Sony version trigger.
    • After setting the V6 II to auto-detect (AUTO) from a manually selection camera system, you must restart the V6 II for the selection to take effect.
    • HSS only works to 1/4000th sec on Panasonic GX85 cameras due to timing differences
    • you may need to remove the hotshoe spring plate on some Olympus E-M1 cameras to ensure good contact, and then you must mount the v6ii and with camera turned on, must press the shutter halfway before turning it on into tx mode . How to make the E-M1 compatible with a Cactus V6 II - note that I do not have a problem with my E-M1 Mark I or E-M1 mark II
    • the locking pin is optimised for Canikon so the locking pin may not lock on Olympus cameras or Olympus flashes (can try pulling the flash back 0.5mm)
  • if you are using a camera brand specific firmware on the transceiver mounted on the camera's hot shoe, the firmware on the V6II attached to a flash must be the same firmware but then theoretically it will allow TTL/HSS/manual power control of the remote flash even if it is a Canon, Nikon or Olympus flash (the exception to this is when using a Sony camera with a V6IIs, the receiver V6II attached to the flash needs to have either Fuji or Sigma TTL (or crossbrand non-TTL) to function

setting it up the first time

  • you need to buy at least two Cactus v6 II transceivers
    • one to sit on your camera, and the other to sit under your flash (whatever brand it may be - although only 60 models have preset functionality as outlined above)
    • alternatively, instead of a 2nd transceiver, you can use a flash with a built-in Cactus receiver such as the Cactus RF60X flash
  • update the firmware
    • download and install the Cactus firmware updater software from and follow the instructions which currently are:
      • without the batteries (2 x AA) in the transceiver and with it turned OFF, attach to your computer USB using your own USB cable (one is not supplied)
      • press and hold the menu button on the transceiver and turn the switch to either Tx or Rx for the computer to recognise it as a USB device
      • run the Cactus firmware updater software and it should detect the transceiver and display a list of firmware options:
        • if you wish to use various systems, and your camera system is not yet available in X-TTL firmware, select Multi-brand HSS then follow instructions.
        • if you wish to use X-TTL on your camera, so you can achieve remote TTL flash:
          • select the X-TTL for your camera brand for your tranceiver that will go on the camera (you then won't be able to use that transceiver for other cameras though, unless you change the firmware again)
          • select a compatible X-TTL firmware
            • yes, this seems weird, but for TTL to work you need TTL firmware on both transceivers!
            • if using Sony camera with a V6IIS, then use Fuji or Sigma firmware on the V6II attached to a Canon/Nikon/Olympus flash (using the Olympus firmware doesn't seem to work)
            • if using an Olympus camera with a V6II, use the Olympus TTL firmware on BOTH the camera mounted and the remote V6II even if using a Canon or Nikon flash
            • if you now use this system specific TTL firmware transceiver on a different system camera instead of as a receiver on a flash, it does not seem to work correctly, even if you change the Camera/Flash Preferences to “Other cameras”, with Fuji Firmware on my Olympus E-M1, it would trigger a flash but the sync speed was dropped to 1/80th sec and the flash output remained constant despite changing the manual flash output on the transceiver.
            • you can however re-install the MultiBrand non-TTL HSS firmware if you wish to restore full control as a transmitter for a camera where there is no system specific TTL firmware.

setting up the on-camera transceiver

  • install the two AA batteries ensuring polarity is correct - ENSURE transceiver AND attached camera or flash are powered OFF before changing batteries)
  • attach to camera hotshoe and apply the hotshoe lock to hopefully avoid it falling off (there has been reports of issues with hotshoe pin not aligning on OM-D models, but I have no issues on my E-M1 and E-M1 II)
  • turn the camera ON
  • half-press shutter button on camera while switching transceiver to TX mode
  • transceiver will then AUTO-DETECT type of camera
  • unless you are using the dedicated Sony version, WATCH the LCD screen to ENSURE the CORRECT system was detected!
    • if the camera was not detected, turn off and ensure transceiver is sitting in hotshoe correctly then re-try
    • if the camera system is not detected, the manual remote control appears to work but doesn't actually change the flash output

optional on-camera transceiver settings

view main settings status screen on the LCD

  • the default LCD screen display is that of the power output settings of each group
  • to view the main settings status screen, press and hold menu button and rotate dial
  • this displays:
    • the camera system and the flash system of the mounted flash
    • flash profile
    • channel
    • sync mode
    • relay mode (REL = relay on)
    • flash power level and zoom
    • delay timer
    • battery indicator

adjust power output of each group of flashes

  • the default LCD screen display is that of the power output settings of each group
  • to change all of them together, just change the dial
  • to change just one group, press and hold the group button (A/B/C/D) until that group lights up on the LCD screen then rotate the dial
  • to disable a group, press the group button once and it will toggle it on or off
  • when the TTL firmware arrives, pressing a group button sequentially will run through group modes of OFF, TTL exp compensation in EV, and manual power output level
  • to LOCK the dial to avoid accidentally changing settings, press and hold the OK button for 2 secs
  • to adjust power of the mounted on-camera flash when TTL Passthrough = OFF, hold menu button then adjust dial (this also toggles between TTL PASSTHROUGH ON or OFF - in which case you select the power output)

adjust zoom on the remote flash

  • press the OK button to toggle between flash output display and flash zoom display
  • adjust as per adjusting power output
  • firmware 1.1.011 gives erroneous Olympus zoom settings (uses a crop factor around 1.5 rather than 2x) of:
    • transceiver setting 16 or 20mm = 12mm on flash
    • transceiver setting 24mm = 14mm on flash
    • transceiver setting 28mm = 17mm on flash
    • transceiver setting 35mm = 25mm on flash
    • transceiver setting 50mm = 35mm on flash
    • transceiver setting 70mm or higher = 42mm on flash
  • the Olympus X-TTL firmware released Dec 2017 has corrected this and now applied the 2x crop factor - setting 50mm on the transceiver will set the Olympus flash to 25mm zoom

adjust sync mode

  • press menu button
  • press OK
  • 1st option is the Sync Mode so press OK button again then the dial to change it to either:
    • Normal HSS - automatically activated HSS / Super FP mode when shutter speed is raised above the camera's flash sync speed
    • Power Sync
      • NB. in Power Sync mode, the flash will fire at FULL OUTPUT as the reason you are using this mode is usually to try to over-power the sun -beware you do not overheat the flash in repeated shots!
      • you might be able to find that speeds around 1/320th sec are more usable with full output flash rather than resort to the reduced output HSS mode
      • at faster shutter speeds even in Power Sync, there is a gradual loss of flash output as shutter speed gets faster
      • you may need to do a bit of trial and error with Power Sync flash delay setting by press and hold OK then activate dial to bring up the Power Sync adjustment option:
        • if you get a black band at the top of the image when you take a shot, you may need to move the setting to the right, and conversely to the left if black band appears at the bottom

flash delay

  • press menu button
  • press OK
  • 1st option is the Sync Mode so rotate dial to next option which is Delay and press OK then using the dial you can set it to OFF, or set msec or seconds (up to 999 secs)

flash relay mode

  • press menu button
  • press OK
  • 1st option is the Sync Mode so rotate dial to next two options which is Delay then Relay and press OK and use the dial to turn ON or OFF
  • setting this to ON allows the on-camera transceiver set in Rx mode and attached to the camera by an appropriate shutter release cable to be activated by a handheld transceiver set in Tx mode (by pressing the transceiver test button) so that shutter is released and the other transceivers set to Rx mode triggered.

flash group sequence

  • press menu button
  • press OK
  • 1st option is the Sync Mode so rotate dial to next three options which is Delay then Relay then Group Sequence and press OK and use the dial to select either:
    • AB-CD
    • A-B-C-D
    • OFF

TTL passthrough for a flash sitting on the transceiver

  • ensure flash is in place and turned on
  • press menu button
  • press OK
  • 1st option is the Sync Mode so rotate dial to next four options which is Delay then Relay then Group Sequence then TTL passthrough and press OK and use the dial to select either ON or OFF

using the transceiver to trigger the camera shutter release

  • connect the transceiver to the camera via an appropriate release cable
  • set the on-camera transceiver to Rx mode
  • use a separate hand held transceiver in Tx mode to trigger the one on the camera

advanced on-camera transceiver settings

  • access by pressing menu button which brings up Function display then instead of pressing OK as for the obove functions, rotate the dial to choose either:
    • preferences
      • AF Assist lamp power
      • AF continuous on/off
      • backlight power
      • backlight time
      • daylight mode
      • swap control zoom or quick power adjust as the function of the dial
      • dial direction
      • temporary unlock
      • sleep
      • factory reset
      • firmware version indicator
    • radio setup
      • channel
      • radio ID - can enter a 4 digit value so your system does not interact with other photographer's system
      • Multi-Master on/off allows multiple photographers to fire your flashes
      • work range short / long
    • power setup
      • power mode relative
      • power mode absolute
    • camera and flash setup
      • just leave this to Auto (Olympus)
      • you may need to use this if you are not connecting the transceiver directly onto the camera hotshoe but using a non-TTL adapter
      • Custom Setting - usually only for flashes without a preset setting

setting up the transceiver attached to a remote flash

  • mount flash to the transceiver and apply the flash hotshoe lock if there is one
  • turn flash on BEFORE the transceiver!
  • turn transceiver to Rx mode
  • the transceiver should auto detect the unit and flash system
    • if it doesn't, you may need to create a manual flash profile and apply it via the Flash System profile
    • download the Cactus Flash Profile Editor software from and install it
    • take the batteries out of the transceiver and connect it to computer via USB cable then activate transceiver by holding menu and switching to Tx or RX
    • run the software and you can create then store a new flash profile, mainly just needs the flash system and the GN in m at ISO 100 at zoom setting of 105mm, and if you are keen, once applied, test the exposures at each power output with the flash in “TTL mode”, and then adjust the flash profile accordingly.
    • each transceiver can store up to 10 custom flash profiles
    • if you don't need to remotely adjust a flash power output, the flash system can be set to “Others”
  • ensure the transceiver channel and radio ID are the same as your on-camera transceiver
  • assign the transceiver to a group - A/B/C/D
  • ensure the flash mode on the flash unit itself is set correctly
    • generally this should be TTL if using X-TTL firmware in the transceiver, and FP TTL or HSS TTL if wishing to use high speed sync
  • hopefully it will just work - fully controlled by the on-camera transceiver

other options which may need setting

  • delay
  • relay
  • sports shutter
  • AF Assist lamp
  • backlight power
  • backlight time
  • daylight mode
  • sleep


  • check status by pressing menu then rotating dial

transceiver TTL mode not firing flash

  • check that the flash is compatible in TTL mode with the Cactus firmware
    • currently only Sony, Sigma, Pentax and Fuji flashes are TTL compatible with the Cactus V6 II / Cactus VIIs
    • if flash is not compatible, the receiver will display — in the power output section and not TTL

in manual mode, receiver output doesn't change with change in transceiver setting

  • ensure correct channel and radio ID on both units
  • ensure the same group A,B, C, D is active on each
  • confirm by half press the transceiver test button and the LED on each unit should light, full press should fire the flash
  • consider changing transceiver to manual only under Power Settings, as the TTL / Manual mix may be causing issues

receiver is set to different output to transceiver

  • check the above issues
  • check that the receiver is not being triggered by another transceiver

receiver shows correct output settings but flash output is not changing

  • ensure the flash is set to TTL mode
  • ensure the flash profile is correct in case you have chosen a manual profile

remote TTL tests with the Sony a7II and various flashes

  • latest Sony firmware in the Cactus V6IIs attached to the Sony a7II hotshoe
  • Sony in Manual mode
  • Cactus V6IIs in TTL mode
  • Cactus V6II with latest Fuji X-TTL firmware attached to the remote flash
flash TTL flash exposure compensation needed PowerSync TTL
Canon 580 EXII +1.0EV
Olympus FL50R +2.5EV 1/250th then “HSS mode”
Olympus FL600R +1.3EV 1/250th only, 1/320th is unusable only top 10% visible
Olympus FL36R +1.3EV 1/250th, higher gives lots of vignetting bottom 2/3rds and HSS-like drop in output
Metz 54MZ-4idigital SCA 3102 M2 Canon foot fires full output n/a

remote TTL tests with the Olympus OM-D E-M1 and various flashes

  • latest Olympus X-TTL firmware in the Cactus V6II attached to the E-M1 hotshoe
  • E-M1 in Manual exposure mode
  • Cactus V6II on the E-M1 in TTL mode
  • Cactus V6II with latest Olympus X-TTL firmware attached to the remote flash
flash TTL flash exposure compensation needed Powersync
Canon 580 EXII +1.0EV 1/250th sec sync, blank above it
Olympus FL50R 0EV Adj = 0 seems best, can shoot at 1/6400th with 10% top vignetted and overall 4 stops loss of flash power
Olympus FL600R 0EV
omd/cactusv6ii.txt · Last modified: 2018/08/01 23:17 by gary1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki