Earlier this month, I kicked off this multi-part series, discussing the longstanding tug-of-war between vertically integrated companies and multi-supplier ecosystems in the context of photography, by showcasing examples specifically relating to lens mounts. However, these aren’t the only tug-of-war case studies in this particular technology and product sector. I’ll continue the coverage here with several strobe illumination source illustrations.
Strobe lights, such as the electronic flash units I’ll be covering here, are sometimes built into cameras for baseline as-needed illumination beyond what’s ambiently available:
More generally, they take the form of one or more distinct light sources physically connected to and controlled by the camera and/or wirelessly managed by it:
As the name “strobe” implies, and in contrast to the continuous light sources frequently found in portrait studios (implementing the popular three-point lighting setup or other arrangement) and on movie sets, for example, the illumination coming from a flash unit is inconsistent, specifically brief, and sync’d to the “open” interval of the camera shutter while the film or image sensor is being exposed.
Early cameras included a “cold shoe”, commonly located on top of the camera, to which the flash unit was physically mounted. The synchronization signal sent by the camera to trigger “firing” of the flash unit took the form of a cable mated to a connector on the camera body:
and plugged into the flash unit on the other end.
The electrical contact subsequently migrated to the shoe itself, leading to its renaming as the “hot shoe” (that said, cold shoes are still quite common, especially in video where they’re used to mount microphones, continuous light sources, external monitors and other accessories to the camera, its cage, handle, gimbal, etc.). The “trigger” voltage supplied by various camera manufacturers (along with various camera models from a given manufacturer, believe it or not) might vary, which proved to be a support challenge for third-party flash unit suppliers (who typically acquire licenses granting access to the confidential info that enables them to make camera-supportive flashes, although some rely on reverse-engineering to accomplish this objective), but “hot shoes” were otherwise largely compatible, at least initially.
Inevitably, however, manufacturers added more contacts to the “hot shoe”, specifically in a manner incompatible with that of their competitors. Additional signal paths might, for example, enable the camera to monitor a flash unit’s battery charge level, as well as its Fresnel lens’ zoom, bounce angle, variable power output and other settings, and display this information to the user in the viewfinder. They might also enable through-the-lens (TTL) monitoring to dynamically adjust the flash output and/or the camera exposure settings not only in advance but also while the image is being captured. And in modern implementations, they also afford support for exotic high-speed sync (HSS) shutter coordination schemes. Here’s an example:
The large contact at the center of the hot shoe is for baseline flash triggering and is generally location- and dimension-compatible from one manufacturer and model to another, allowing for elementary cross-platform illumination support. Minolta-now-Sony, however, has transitioned to a more proprietary hot shoe implementation:
And things get even more complicated when a photographer wants to remotely trigger flash units not directly connected to the camera. The most common, albeit also the most limiting, approach to accomplishing remote flash triggering involves leveraging infrared light. The primary flash unit (or alternatively, a control transmitter), directly connected to the camera, sends out a (camera manufacturer-proprietary, unsurprisingly) infrared-encoded signal sequence received by one or multiple remote secondary flash units, which fire(s) in response.
The limitations of this approach are numerous. For one thing, infrared-based triggering typically doesn’t support any of the previously discussed advanced sync and broader control techniques. The communication link between primary and secondary units is also unidirectional-only; a remote flash unit can’t alert the primary controller when its batteries are running low, for example, or when it’s not yet recharged and ready for the next shot. Ambient infrared-spectrum light can interfere with the transmitter-to-receiver link. And infrared connectivity requires line-of-site positioning between primary and remote units: unachievable in some multi-flash setups, not to mention when a flash is embedded within a softbox or other diffuser.
The alternative approach, as you may have already guessed, involves RF connectivity, often leveraging one of the unlicensed ISM bands. Here again, the implementations are typically proprietary (frequency, protocol, etc.). I have several flash units for my Panasonic mirrorless cameras, for example, made by Chinese manufacturer Godox, whose devices are also resold by Adorama, a large US-based retailer, under its exclusive Flashpoint brand. Godox and other third-party flashes are generally not only lower-priced than Panasonic-branded alternatives, they’re also often comparatively feature-rich. They don’t interoperate with Panasonic flash units from an RF triggering standpoint, however, nor with anyone else’s—Godox’s 2.4 GHz “X” protocol is unique to its own hardware. More generally, because Godox units are camera brand-specific, if (for example) you switch from Panasonic’s ecosystem to Canon’s, existing flash units you already own will no longer work; you’ll need to buy brand new Canon-supportive ones instead.
Another equipment supplier, Hong Kong-based Cactus (a brand of parent company Harvest One), came up with a clever workaround for this camera brand “lock”. The hot shoe layout found in the company’s primary flash units and transmitters was (note the tense; keep reading) sufficiently flexible from a contact array option standpoint to support multiple (and more generally most, but not all) manufacturers’ hot shoe schemes. To switch from Panasonic’s to Canon’s ecosystem, for example, all you needed to do was to tether the Cactus device to a computer and download a new firmware image. Here, for example, is one of the multiple Cactus V6 II wireless flash transceiver units that I own:
A hot shoe on the transceiver underside interfaces with the camera:
while a topside hot shoe enables optional direct mounting of either a Cactus- or other camera manufacturer-supportive flash unit. Secondary receivers and flash units communicated with the primary transmitter over Cactus’ proprietary 2.4 GHz RF triggering scheme:
The one “fly in the ointment”, as you may have already guessed, was Minolta-now-Sony’s proprietary physical hot shoe approach, which necessitated a Sony-only Cactus transceiver:
Unfortunately, Cactus went out of business a bit more than two years ago, a fact which I learned only after I’d bought a portfolio of used Cactus gear from various sellers on eBay. I hadn’t been aware of the company’s demise upfront because its website remained “up”…at least for a while. But earlier this year (ironically only around a week after I downloaded Pentax-specific firmware to the last piece of Cactus hardware I’d bought), the site server went offline. This shutdown is particularly unfortunate (not to mention eerily reminiscent) because device firmware images were solely housed in (and downloaded by the firmware update utility from) the Cactus “cloud”. Although I’m able to continue using my Cactus acquisitions with my existing Pentax cameras, not only have future bug fixes and feature set updates ceased, I also won’t be able to use any of the Cactus gear with non-Pentax camera bodies in the future.
For any of you who are also photographers, I’d love to hear about the interoperability limitations and workarounds (and shortcomings of those workarounds) that you’ve personally come across and dealt with. And case studies from other technology sectors are also welcome, of course! Sound off in the comments with your thoughts.
—Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.