Top critical review
Spend your money more wisely
on 24 October 2017
The manual says the guide number is 15, but doesn't specify units. I'm guessing in feet, at 1600ASA.
Worryingly, the "flash" (I use the word advisedly) is visible in the viewfinder after the mirror has fallen. That seems like a lot of wasted light to me.
Oh well, what do you expect for less than 20 quid? Maybe performance like my old Vivitar xenon ringflash. That cost about twenty quid, IIRC