this was the flagship model for Olympus, the R designation is the newer version which allows optical remote TTL flash, this has now been replaced by the FL-900R.
GN 50m at ISO 100 at maximum zoom setting of 42mm (= 85mm in 35mm terms)
350g, 4x AA batteries, tilt and swivel including 7deg tilt down for macro, AF assist beam, supports Super FP flash (high sync flash)
built-in flip out wide diffuser to cover focal lengths 8-12mm
?2.5-6sec sec recycle time from full output
no modeling light – but then I have not found this useful anyway on a portable strobe
it’s exposure compensation (up to +/- 3EV) is additive to camera flash exposure compensation setting.
as with all portable strobes, it must be rested for 10min after high burst rates – at full power, rest after 10 shots at 1sec intervals, or at 1/8th power, rest after 80 shots at 0.2sec intervals.
optional high voltage pack (HV-1) allows recycle time to be reduced to 1.3sec for full output, and allows up to 40 frames at up to 8fps at 1/8th power instead of 5 frames without it.
optional FP-1 power grip with 4x C cell batteries allows elevated flash position to reduce red eyes, extended battery life and shorter flash recycle time, but can ONLY be used with the FL-50, FL-50R and the macro flash set, although allows use of the HV-1 pack for even faster recycling
the cheaper, discontinued FL-50 is identical but does not support wireless remote TTL flash.
Panasonic re-badge the FL-50 as the Panasonic DMW-FL500E