User Tools

Site Tools


photo:diy_flash

troubleshooting flash not firing or exposing correctly

see also:

flash not firing

  1. make sure flash is turned on and ready light comes on
    1. if ready light does not come on, the batteries are too flat, inserted incorrectly, or terminals are corroded, or flash is faulty.
    2. you should be able to press a button on the flash to do a test fire to confirm the batteries and flash are OK
  2. make sure flash is connected properly to the camera
    1. hotshoe mounted:
      1. ensure flash is mounted secured in hotshoe and hotshoe contacts of both flash and camera are not dirty
      2. ensure flash is compatible with hotshoe
    2. PC sync cord connection:
      1. sync cord connections can be problematic at either end or within the cable itself
      2. if connections seem OK, you may need to try another cable
    3. optical wireless remote control:
      1. you will need a master controller flash connected to the camera
      2. the camera will generally need to be set to optical RC (eg. on Olympus cameras, RC mode = ON)
      3. the compatible remote flash will need to be in line of sight of the master flash and within its range and its RC group set to the same group as on the camera or master flash controller (see instruction manual)
      4. it will probably not work in bright sunlight
    4. radio wireless remote control:
      1. you will need a compatible master radio wireless controller flash connected to the camera (some cameras, such as latest Canon and Nikon have thus built-in to their cameras but this requires brand-specific radio wireless flashes - alternatives include Godox and Cactus)
      2. ensure camera optical RC is turned OFF
      3. the compatible remote flash will need to be in range of the master controller and its remote group/channel and perhaps radio ID PIN set to the same as on the camera or master controller (see instruction manual)
      4. water including water pipes tends to block radio signals
  3. make sure the camera is set to fire the flash
    1. on many cameras, including Olympus, if the flash mode in the menu is set to OFF or even perhaps AUTO, the flash may not fire - you may need to set it to FILL IN to ensure it fires
    2. on many cameras, if you choose a shutter speed faster than the flash sync speed, the camera will not fire the flash unless you put flash into high speed sync or Super FP mode
    3. on some cameras, choosing silent electronic shutter mode will stop the flash firing

a band on one of the sides of the image is dark

  • this indicates you are using a shutter speed faster than the flash sync for that set up, either:
    • use a slower shutter speed, or,
    • change the flash mode to high speed sync or Super FP mode
  • if using a film camera, this may also mean you are using the incorrect sync setting - for most SLRs, it should be X mode not FP mode

image is too dark

  1. check that the flash fired by watching it fire during shutter release (if not, see above)
  2. check that the flash is aimed at subject (or bounced onto subject)
  3. check that the flash is powerful enough to light the subject with the camera settings:
    1. test this by putting flash in full output manual flash exposure:
      1. if still dark, then you need to either:
        1. use a wider aperture
        2. use a higher ISO
        3. move flash closer to subject
        4. use a more powerful flash or more flash units
        5. if using high speed sync or Super FP mode, turn this off or use a lower shutter speed as this mode reduces maximal flash output significantly as the shutter speed gets shorter
      2. if image is now too bright or over-exposed:
        1. if using TTL flash, you may have set the flash exposure compensation too low, in which case go back to TTL mode and increase the flash exposure compensation setting

image is too bright

  • is the image too bright from the ambient exposure?
    • test by taking a shot with flash turned off, if still too bright then the ambient is over-exposed, so either:
      • if using an auto exposure mode, set exposure compensation to a lower level, otherwise,
      • use a faster shutter speed (up to the flash sync level)
      • use a lower ISO
      • use a smaller aperture
      • use a ND filter or polarising filter
    • NB. if using Aperture Priority mode with a wide aperture, check that the camera has not changed the shutter speed down to the flash sync speed and in so doing has overexposed the ambient light, if this is the case, either:
      • use a lower ISO
      • add a ND or polarising filter to reduce the light
      • use a smaller aperture
      • change to high speed sync or Super FP mode
  • if the ambient exposure is OK but flash is too bright:
    • if using TTL flash, check the flash exposure compensation setting is not too high
    • if using manual flash, change the output level to a lower level
    • note that flash units can only reduce output to a certain amount, often 1/256th of full power, and this may still be too bright, in which case:
      • move flash further away or add a diffuser over the flash, or bounce the flash, or,
      • use a lower ISO
      • add a ND or polarising filter to reduce the light
      • use a smaller aperture
photo/diy_flash.txt · Last modified: 2018/06/16 08:10 by gary1