remote TTL flash RC mode with the Olympus OM-D cameras

see also:

• the Olympus OM-D system and how to make the most of it
• using the Olympus OM-D cameras with flash
• manual flash with Olympus cameras
• super FP flash mode
• remote radio wireless flash with the Olympus OM-D cameras
• TTL flash for Micro Four Thirds cameras
• links to instruction manuals for Olympus flashes
• How the Olympus RC pulses work

• remote TTL flash is the use of a flash which is not physically connected to the camera but whose flash output and thus exposure is controlled and triggered by the camera - in the Olympus case, as is the case for most systems, this control is via infra-red or visible light and requires that a pre-flash is performed so the camera can determine the flash output and a 2nd pre-flash to trigger the main exposure.
• Olympus calls this RC mode (“remote control” mode) which is similar to Canon's remote E-TTL flash mode
• most of the current Olympus Micro Four Thirds system and Olympus Four Thirds dSLR system cameras have remote TTL flash capability - a function that is NOT available on any Panasonic camera prior to the Panasonic GH-3.
• the Olympus OM-D E-M5 is the 1st compact system digital camera to allow a flash sync as fast as 1/250th sec, but this is only possible when all the components in the set up are the latest flash systems such as the Olympus FL-600R flash.
• the Olympus FL-600R and the supplied plug-in flash are the 1st external Olympus digital flashes with RC Commander functionality - ie. can control other Olympus R flashes in RC mode when mounted on the camera.
• the older Olympus R flashes only work as slaves in RC mode.
• the Olympus FL-600R has a totally new control panel user interface.

• all current Olympus Pen, OM-D and Four Thirds cameras are compatible with Olympus RC TTL flash system
• only the latest Panasonic cameras such as the GH-3 has this functionality
• the E-M5 and later cameras have additional functionality:
  • flash sync 1/250th sec when using FL-600R flashes
  • allows the FL-600R flash to be mounted on the camera and used as the Commander RC unit
  • allows the camera mounted flash to also act as one of the flashes in the set up (on older cameras, the camera flash acting as RC Commander did not contribute to the exposure and usually could not be selected in the RC control panel)
• camera must be set to RC = ON

• on older cameras this is the built-in flash
• on the E-M5 you can use the supplied plug-in flash or a FL-600R flash

• any Olympus flash with R as a suffix in the model name
• the flash must be set to RC mode and in range of the RC Commander's output

• flash sync in RC mode with older flashes (FL-36R, FL-50R, FL-300R) drops back to 1/160th sec instead of the expected 1/200th sec flash sync
  • presumably if all the slave units are FL-600R flashes, the the flash sync on the E-M5 will be 1/250th sec as for non-RC mode
• the FL-36R or FL-50R mounted on the camera cannot act as a commander as they do not have this functionality - you must use a flash capable of commanding the RC outputs - for most Olympus cameras this is the built-in flash or the new FL-600R, but as the E-M5 does not have a built-in flash, the supplied plug-in flash will function in this manner.
• it seems the FL-600R's commander mode only works on the E-M5 and not earlier Pen or Four Thirds dSLRs ¹⁾
• the colour temperature of the Olympus flashes varies with flash intensity, so it is usually better to use auto WB rather than set a given temperature.
• if using the supplied plug-in flash:
  • it seems to always fire a visible flash even if deactivated which DOES impact the image and your subject - presumably it has no infrared transmitter.
    • in macro situations the output from these pre-flashes may contribute to the exposure inadvertently, particularly in 2nd curtain mode as the flash needs to fire again to trigger the slave flash before the shutter closes.
    • it appears to fire with an effective GN of ~1m at ISO 200 which is problematic when using wide aperture lenses at close distances
  • it must be raised up to fire (except on Program Auto mode)
  • NB. unlike the Olympus Four Thirds dSLR system cameras it CAN be used to fire a flash exposure if being used in RC mode but remember it is only a low GN flash.
• the compact FL-300R flash only can be set to group A or B (not C)
• Olympus do not have an infrared RC transmitter similar to Canon's ST-E2 Speedlight Transmitter for more discrete RC usage
• Olympus do not have an RC compatible macro flash system
• if using 2nd curtain sync, the shutter speed should not be longer than 4 secs as the flash will automically fire by 5 secs in long exposures (FL-50R instruction manual p.35)
• the Metz 15 MS-1 slave macro twin flash requires firmware v3 or higher to be used in remote TTL mode on Micro Four Thirds cameras

• as an aside, for some reason Olympus mount flashes such as the FL-36R/50/600R/Metz flashes do not seem to fire in pass-through non-TTL mode on Pocket Wizard Mini TT1 or Flex-TT5 radio controllers whereas Canon mount flashes work well with the E-M5 with these (albeit in non-TTL Auto or Manual slave modes)
• PocketWizard does not support Olympus TTL flash for radio wireless TTL as it does for Canon or Nikon - but this may be coming in the next few years given the popularity of the E-M5

• attach a commander-capable flash to the camera (eg. the supplied plug-in flash or a FL-600R)
• turn on your external flash(es) and set:
  • press mode button until mode is RC - displays Cx Z rC where x is a channel 1/2/3 and Z is the group A/b/C
  • NB. do NOT get confused with the “slave” mode as this is for non-TTL auto or manual exposure optical triggered slave flash
  • optionally, hold down the zoom button for a couple of secs and you can select the zoom setting of the flash
• ensure the flash front sensors are line of sight visible to the camera flash:
  • generally must be within 50deg of the central axis if up to 5m from camera, but within 30deg of central axis if further than 5m.
  • preferably ensure the flash sensors are facing the camera (BUT if using the flash in non-TTL Auto slave mode, the sensor must face the subject for correct exposures)
  • the above may not be critical in small rooms where the signal can bounce off walls
  • avoid using more than 3 flashes in each group
• if using the plug-in flash it MUST be fully raised to work!
  • the only exception to this is when using underwater modes but then these set camera to 1/80th sec and f/8 or f/4 aperture depending on the selected mode.
• on the E-M5:
  • on the menu, camera 2 section, set RC mode to ON
  • on the Control Panel, ensure flash mode is set to Fill-in or 2nd curtain (even if you don't want the on-camera flash to affect the image exposure)
  • on the Control Panel, with flash selected, press INFO button to toggle to the RC settings:
    • the channel must be set to the same channel you have set for your flashes
    • you can then turn on/off each flash group (A/B/C/camera) and set their individual flash exposure compensation
    • you may need to set the strength of the RC beam to medium if the flashes do not fire on low output beam
    • in bright sunlight, you may need to resort to FP setting to allow faster shutter speeds to avoid small apertures
• many experienced photographers prefer to set the camera to Manual (M) mode for exposure when using flash (on the top dial of the E-M5):
  • you still have TTL automatic flash exposure assuming the RC control panel for the flash group is still set at TTL and not M
  • BUT gives you control over setting ambient exposure (how light or dark the background or regions not lit by flash are) and DOF by modifying aperture, shutter speed (up to the flash sync speed unless you use FP mode), and ISO.

• attach a polarising filter if you wish to use f/1.8 aperture indoors and you wish to minimise effects of office lighting
• attach the Metz 15 MS-1 to the lens via the filter thread adapter (you may need step up rings for the Olympus 45mm f/1.8 lens for example)
• attach the diffuser cover to the Metz flash and turn the flash on
• set the Metz to slave mode (as Oly TTL mode does not seem to work with the E-M5 unless you apply a Metz firmware upgrade to the flash) by holding in the AF button and following instructions
• set the power output of the Metz to about 1/16th (this will give you ~1 EV under-exposure if subject is ~1.5m away which is fine for fill-in)
• set camera to ISO 200, manual exposure mode, 1/200th sec, f/1.8 (a slower shutter or higher ISO will increase the effect of office lighting!)
• attach FL-600R flash to camera, ensure it is in TTL mode
• if using RC mode as set up above, set the camera flash to TTL (set it OFF if you wish to assess the contribution of the Metz flash and ambient only)
• flash mode should be flash on
• flash exposure compensation should be 0.00
• swivel and tilt the FL-600R flash head so it aims at a white wall or ceiling in suitable direction to give a 45deg angle bounce back down to your subject
• start experimenting - adjust Metz power output as desired
• if you really want to get clever you could add a rear “kicker” or hair light flash using a FL-36R or similar, with a bit of black material wrapped around it to reduce the coverage of light to only where you want it - set it to a Group such as B or C, then in the RC control panel on the camera, set that group to TTL and adjust exposure compensation accordingly (or you could set it to manual and you would then need to set the flash to the desired flash output)

• see remote radio wireless flash with the Olympus OM-D cameras