omd:flash_superfp
super FP flash mode
introduction
SuperFP is a special flash mode which allows shutter speeds to be used faster than the x-sync capability of the camera-flash system
this is a mode invented by Olympus in the 1980's and 1st used on their
Olympus OM system
other manufacturers have adopted this technology and call it High Speed Sync or HSS
FP stands for Focal Plane shutters
why can't we use normal mode flash at any shutter speed?
cameras such as most film SLRs and digital SLRs as well as mirrorless cameras have a mechanical shutter which sits in front of the film or sensor
at speeds at the “x-sync” or slower, this shutter is fully open when the flash fires and thus the who image is equally illuminated by the flash.
at speeds faster than the x-sync, the 2nd curtain of the mechanical shutter starts closing in front of the film or sensor while the flash fires, and thus a horizontal segment of the image will not be illuminated by any of the flash.
the faster the shutter speed, the greater the proportion of the image that will not be lit by the flash
cameras using an electronic global shutter mode without any mechanical shutter may be able to sync at any shutter speed, and this will be a highly desirable feature once the issues with such sensors are resolved, and this technology will potentially negate the need for a Super FP or HSS flash mode.
how does Super FP mode help solve this?
in Super FP mode, the flash fires a series of pulses throughout the exposure to give the effect of continuous lighting for the duration of the exposure
this then allows the whole image to be lit by the flash no matter how fast the shutter speed
HOWEVER, there is a MAJOR COMPROMISE - the effective flash output decreases substantially with every increase in shutter speed above the x-sync - this is why this mode cannot be used to overpower the full sun - your maximum
flash_GN falls at much the same rate that the ambient light is decreased as a result of shortened exposure
why then would we use Super FP flash mode?
you need wide aperture for shallow DOF
the main reason is to allow a wider aperture and shallower
depth of field (DOF) such as when using the flash as a fill-in light in outdoor portraiture in bright conditions
an alternative solution is to use a ND filter, but then this may adversely effect the ability of the AF system if the resulting light is too dim or the optical viewfinder view may be very dim, and of course you need to get the correct ND filter and put it on your lens
you need a fast shutter speed to stop subject blur
how to set Super FP mode using an OM-D camera with an Olympus flash
The bundled flash that comes with the E-M5 or the built-in flashes cannot be used in SuperFP mode UNLESS RC mode is set to ON as this is the only setting within the camera where SuperFP can be turned on (see instructions as for the FL-600R)
External flashes with a mode button which allows SuperFP can also be used with RC = OFF.
using the Olympus FL-600R flash
using RC OFF
a hack to allow manual radio wireless remote Super FP flash
if you want to trigger a remote Olympus Super FP mode compatible flash via radio wireless there is a workaround
start with the flash on the camera with RC = OFF on the camera
switch on flash and the camera
on the flash set mode to manual FP
the camera will now be set to FP mode
without turning the camera off, turn the flash off and remove it from the hotshoe
put a basic manual radio wireless remote trigger on the camera hotshoe and a receiver on the flash hotshoe
ensure the wireless trigger is set up correctly (ie. correct channels on each)
turn wireless trigger units on
turn the flash back on and it will be still in Manual FP mode so when it fires it keeps pulsing light at whatever output you had set
as long as the camera does not go to sleep or turn off you should be able to choose and shutter speed and gain FP mode flash albeit in manual flash output without any flash exposure compensation, etc.
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using RC ON
in this mode, you are instructing the camera to use remote control of flash and to remotely set the settings of each flash and the controls on any attached flash will become deactivated and mode will display as RC (physically remote flashes will need to have their mode set to RC with the correct channel and group)
set the menu to RC = ON in camera settings 2 menu to activate remote flash functionality
while in Live View, press OK to display camera settings, if the remote flash settings are not displayed, press the INFO button to toggle to these
the top right item of the remote flash menu needs to be set to FP
then for each flash group you need to select either:
FP TTL - flash group will be set to automatic TTL exposure in Super FP mode, you need to also set the flash exposure compensation in this display
FP M - flash group will be set to manual exposure in Super FP mode, you need to also set the flash output level in this display
OFF - flash group will not fire
omd/flash_superfp.txt · Last modified: 2016/08/06 19:15 by gary1