Does anyone know the origin of the the word "stofen" and its correct — or at least accepted — spelling? I've seen it spelt "stofen" (which seems to be the most frequent variant), "Stofen", and "Sto-Fen". By stofen I mean the translucent, white, plastic diffusion "cups" that press on to the head of a portable flash.

Although, it seems to me most people use the word "stofen", perhaps it isn't the name most people use. The American company Sto-Fen, offer a "stofen" they market as the Omni-Bounce. And I've seen the word "softy" used and also "diffusion dome" — which, I think is used improperly as the things are rectangular in shape and not domed.

If "stofen" is the canonical form, did the word derived from the name of the Sto-Fen company? And, if so, was it because they invented the "stofen", or simply popularised something that was already in use?

  • \$\begingroup\$ I guess I'll have to stop calling it a Fonger now that you've introduced me to the proper name...nope, it'll always be a Fonger :-) \$\endgroup\$
    – OnBreak.
    Apr 15, 2018 at 5:40

2 Answers 2


I am quite certain that "Sto-Fen" is just the name of one company.

As you note, that company doesn't call their product a "stofen" — they call it the "Omni-Bounce". I don't find any evidence for any prior generic use of the Sto-Fen name anywhere — or for that matter, much use today. If you do a Google Books search, you only get references to this product from the same company, going back to the late 1970s / early 1980s. If it were a previously-used term, you'd see it show up (as for example "speedlite" does).

The trademark for "STO-FEN" was only filed in 2011, but notes May 31, 1979 as the first use in commerce — presumably before then, it was ™ rather than ®. Crucially for the etymology question, though, the registrant is Ernest C. Fenn. Presumably, the last part of the company name comes from this last name.

The general name of such a device is "push-on diffuser" — "diffusion dome" is also common, even when the shape isn't actually a dome. (See for example the SW-14H Diffusion Dome from Nikon.)


Etymology of the word “stofen"?

I hope this isn't too much of a stretch (pun intended) unlike the Stofen company some flash diffusers are made of cloth. German: cloth, fabric, material or Dutch: fabric (made of fabric).


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