Are the Yongnuo clones of Canon flash equipment and lenses legal to sell/buy?

Yongnuo has recently released their 50 mm f/1.8 lens that is almost identical to the Canon 50 mm f1.8 in their external design. They've also created a lot of clones of Canon flashguns and accessories like YN600EX-RT (Canon 600EX-RT) and the YN-E3-RT Radio Transmitter (ST-E3-RT Speedlite Transmitter) that are actually not that easy to tell apart from the Canon counterparts.

I guess that the patents regarding the 50 mm lens might be outdated, but the 600EX-RT was released in March 2012 so surely its protection must still be valid.

How can these products be legal to sell, and perhaps more important to photographers, are they legal to buy?

I realise that law may differ a lot between countries, but a general answer would be helpful too.

Answer

There are several different types of intellectual property, which might apply here, but I don't see any indication that they do. As you say, the specifics may depend on jurisdiction, but a lot of this is effectively global. Let's start with what definitely doesn't apply:

• 
  

  A. Copyright. This is a product, not a creative expression. There are some cases where there might be technicalities over whether certain ornamental elements could be covered by copyright, but that really seems unlikely to affect anything here.

  
  


• 
  

  B. Patents. What we normally think of as patents are utility patents, and these don't cover form; they cover function. (But see below.) It's possible that there is some internal patent dispute over the technology, but I don't know of any of these flashes doing anything incredibly novel, so that seems unlikely. If it does apply, it's to the implementation of some idea, not the idea itself, and most importantly from this point of view, not to apparent similarities in appearance. (As the petapixel teardown and review @inkista mentioned shows, while the end result is similar, the actual implementation is very different.)

  
  


• 
  

  C. Trade secrets. Well, okay, maybe — but that's between the industrial espionage and counterespionage units of each company :). Again, doesn't really apply to your concern.

  
  

So, what does that leave?

1. 
   

   Trademark. A few product designs are trademarked (like the shape of Coca Cola's bottle). Most aren't. The main consideration is consumer confusion (which given the clearly different branding, seems unlikely to be an issue here). Companies are always pushing at this, and it's quite common for "generics" to be quite close in actual appearance as long as they're labeled differently. "Trade dress" — the appearance of the product — can also apply here, but Canon would be on stronger ground here if they had a history and pattern of a consistently distinctive speed light design very different from all the others out there. They don't.

   
   


2. 
   

   Design patents. We saw this one in the Samsung / Apple fight over rounded black rectangular slabs. Could apply (for example, perhaps to the pattern made from the placement of the buttons), but, again, the design isn't really strongly unique or distinctive. Canon could pursue this, but the reward would be rather low because it'd be easy for Yongnuo to make changes to stay clear. It's more of a big deal in high-fashion consumer products — like smartphones. Canon's probably better off just taking the high road and trading on consumer confidence in the quality of their name, not getting into this kind of fight.