see also:

• using the Olympus OM-D cameras with flash
• remote radio wireless flash with the Olympus OM-D cameras
• remote TTL flash RC mode with the Olympus OM-D cameras
• super FP flash mode
• manual flash with Olympus cameras
• flash x-sync in Olympus digital cameras

• Olympus digital cameras have several flash modes available in the camera menu:
  • Auto
  • RedEye
  • Fill-in
  • Slow1 Redeye
  • Slow1
  • Slow2
  • Manual Flash - you set the power output of the built-in or bundled flash unit
• in addition to these, one can use remote control flash - see remote TTL flash RC mode with the Olympus OM-D cameras, in which case the camera can remotely control flash modes and outputs of attached and compliant remote flashes from within the special RC Mode panel (via INFO button if RC Mode = ON)
• if you want to avoid annoying pre-flashes:
  • use Fill-in mode, plus,
  • flash unit set to manual (no red eye nor TTL exposure determination flash will be fired), plus
  • RC Mode = OFF (no remote control flashes will be fired), plus
  • AF Illuminator = OFF

• cannot use SuperFP mode on your flash in these modes - must use Fill-in mode to allow SuperFP flash.
• the flash MAY NOT fire!
• the flash will ONLY fire if the shutter speed is within the following range:
  • slowest shutter speed:
    • the highest of:
      • 1/(2 x focal length), or, (unfortunately, Olympus is yet to factor in effect of image stabiliser)
      • your SLOW LIMIT setting (Menu:Cogs:F:Slow Limit)
  • fastest shutter speed:
    • the lowest of:
      • x-sync for your camera-flash combination as determined by your camera, or,
      • your x-sync setting (Menu:Cogs:F:X-sync)
• Red Eye mode just fires an additional pre-flash to constrict the pupils of your subject and thus reduce chance of red eyes

• flash will ALWAYS fire
• this mode works extremely well with the PASM mode on the camera set to M (manual)
  • setting the aperture controls depth of field (DOF)
  • setting the shutter speed controls ambient light exposure
  • can increase ISO if need more flash output, but these also increases ambient exposure
  • lowering ISO to LOW (100) +/- using a polarising filter or ND filter allows wider apertures in bright sunlight
• this may cause ambient over-exposure in certain modes as shutter speed will be restricted if using a compliant flash unit as follows:
  • slowest shutter speed:
    • in PASM M mode:
      • functions as SLOW1, hence there is no option to select SLOW1
    • in PASM modes other than M:
      • your SLOW LIMIT setting (Menu:Cogs:F:Slow Limit)
      • the focal length limit is thankfully ignored in these modes
  • fastest shutter speed:
    • the lowest of:
      • x-sync for your camera-flash combination as determined by your camera, or,
      • your x-sync setting (Menu:Cogs:F:X-sync)
• faster shutter speeds CAN be used if either:
  • flash unit is also set to Super FP mode (FP TTL or FP Manual)
    • see super FP flash mode
  • flash unit is a non-compliant flash or connected only via the central firing pin or PC sync cord
    • be aware that shutter speeds faster than x-sync result in progressively more “blacked out” areas which only receive ambient exposure but no flash exposure
    • this is still useful up to 1/400th or maybe 1/500th sec if you subject is not within the blacked out area at top of image.

• ensures the built-in flash (if there is one) or attached flash never fires even if scene is underexposed

• ignores the SLOW LIMIT and the annoying 1/(2xFL) rule
• otherwise functions as Auto if in PAS or Fill-in if in Manual exposure mode
• SLOW1 = 1st curtain:
  • fires flash at start of exposure
• SLOW2 = 2nd curtain sync or rear sync:
  • fires flash at end of exposure, thus used for those moving car shots with trailing tail lights
  • see also: https://photofocus.com/2015/01/24/how-to-make-magic-with-a-flash-and-rear-sync/

Rear curtain sync effect with slow shutter speed courtesy of photofocus

• sets the following which cannot be altered:
  • Slow1 Auto Flash, face AF, f/4, ISO200, exposure compensation = -0.3EV (to under-expose ambient)