As regular readers know, I get frustrated by manufacturer intransigence be it in the form of ridiculously high prices for connection cables (PocketWizard) to leaving out basic functionality (Canon). Fortunately, photographers have a helpful resource in Lon and Bonnie at FlashZebra.com
Canon made a decision, faulty in my perspective, to leave out true basic optical triggering on their current Speedlites. They claim optical slave capability but it's really infrared slave control. What I needed was the ability for the 600 EX-RT to flash whenever it saw another flash go off, not just a Canon specific signal. Nikon does this, every third party flash does this, it's just asinine that Canon does not. Fortunately, the good people at FlashZebra.com have true optical slaves that can connect to Canon Speedlites that send the fire signal whenever they see another flash. Very simple and a real solution to a problem.
The other completely idiotic thing that Canon did was disable rear curtain sync if the flash was not in the hot shoe or the transmitting function was enabled on many of their cameras, with this dumb choice impacting me on the 1Dx. Canon's own off camera cable, the OC-3 is very pricey and very short. FlashZebra to the rescue with their long off camera cable. Now I like stringing cable not much at all, but when needs must, and they do, this 24' long alternative to Canon's pricey and shrunken offering solves the problem. The foot is metal so it won't break off, and the flash holding shoe can be mounted to anything with a ¼-20 stud, such as a tripod, light stand or clamp. It also preserves full eTTL.
One could make legitimate argument that manufacturers should be more customer centric. But there is a lot to be said for the small independents who "get it". They understand the reality of photographic endeavour and deliver solutions to the problems at fair prices.
So if you find yourself searching for something special to use with your flash, be it hotshoe or strobe, or trigger accessories and other enhancements, you owe it to yourself to set a bookmark in your browser for FlashZebra.com You may not use the site every day, but when you need that answer, they might just be able to help you out. Lon and Bonnie are really cool folks as well so it does your karma well to support them when you can.