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flash triggering trough WiFi


cohen5538
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Why not using the wifi capability of sony a7, in order to trigger an off camera flash?

After all, as far as I understand Wifi works on 2.4Ghz, some of those radio triggers works on 2.4ghz.

It's all about new app that will use the right protocol.

Will still need the Receiver on the Flash, but we would not need the Transmitter over the camera. 

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You need 2 flashes to start with:

 

One that will be on-camera and will be the "Control" unit. It can be any of the following: HVL-F20M, F32M, F43M, F60M OR using an adapter (sony ADP-MAA) HVL-F20AM, F43AM or F58AM). These last 3 units are from the Alpha mount series and use the Minolta/Sony foot. Note that the F20M and F32M don't provide all the features available through the 43 and 60 models like channel selection, groups and ratios between groups. I don't recommend the use of an adapter for regular on camera use since some people lose their flash by dropping when the adapter can get loose without noticing.

 

One or more of the following as remotes: Sony HVL-F32M, F43M, F60M and from the previous generations of cameras/flashes: Sony HVL-F36AM, F42AM, F43AM, F56AM, F58AM and Minolta or Konica Minolta 3600HSD or 5600HSD. The Minolta 3600HSD and 5600HSD are the exact same as the Sony HVL-F36AM and 56AM respectively. All of these will work in all of their native modes, meaning if a flash model has no Manual mode provision, it won't work in manual and so forth for other flash models.

 

A good resource on this is: http://mhohner.de/sony-minolta/flashcomp_setups.php#wireless

Use the interactive chart at the bottom to see what works

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michelb Thank you for the detailed explanation.

 

Which brings me back to my first idea. I.e. as regard to Manual Flash, we could establish off camera flash system. By Pairing the Yongnuo 560iii which has already built in 2.4Ghz receiver (70$) to the Sony A7 Wifi functionality.

 

 

 

 No need of two flashes, no need of RF-603 nor PocketWizard.Now. if we could establish this manual flash "Wifi Pairing". Why not doing so with TTL flash? 

 

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Current systems use some basic radio protocol (or none at all) to manage the Flashes. The system is easy to configure and use, the radio connection is basically an invisible wire. WiFi is a significantly more complex radio protocol, its no longer an invisible wire. It may not be suitable for firing a flash because the protocol itself is designed for robust data transmission, not realtime flash control.

 

It could be possible, but the current solution has many advantages too, and AFAICS camera makers really do struggle with software interfaces - WiFi barely works ... I'm sure someone will eventually make it.

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Current systems use some basic radio protocol (or none at all) to manage the Flashes. The system is easy to configure and use, the radio connection is basically an invisible wire. WiFi is a significantly more complex radio protocol, its no longer an invisible wire. It may not be suitable for firing a flash because the protocol itself is designed for robust data transmission, not realtime flash control.

 

It could be possible, but the current solution has many advantages too, and AFAICS camera makers really do struggle with software interfaces - WiFi barely works ... I'm sure someone will eventually make it.

 

This is basically nonsense and I don't know where you studied radio transmission but even if we are to accept this nonsense as fact, you need only look at a USB wifi dongle or even an eye-fi card to see how cheap, small and easy it would be to implement this into a flash. Radio controlled helicopters use a 2.4ghz signal and whether you wish to modulate, encrypt or do whatever to that signal is somewhat irrelevant. The transmitter exists within the camera to control a flash wirelessly. The reasons it is not done are either a lack of foresight or simply it is cheaper.

 

Similar arguments were had where people stated the "5d mk 3 cannot use radio!! its body is metal!!" yet the new 5d somehow gets around the metal body problem and an eye-fi card does too.

 

I think the reality is that people read half a sentence of a wikipedia article without understanding much about the subject and then try to pass a second-hand, taken-out-of-context opinion, as fact. It's a shame because although cohen might be slightly misguided, his argument in its entirety is invalid and fanboys typically wash over arguments like this, making it easy for companies like Sony not to improve on their products. Why should they when people are so willing to argue against an innovative idea rather than for it? It is sad

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I have an electrical and computing engineering degree ... what do I know  :D

Obviously not very much, I doubt you could tell me what the optimum length of an aerial would be for the 600ex-rt. What is an "electrical and computing engineering degree". Is it like a computer science degree and an electrical engineering degree combined, studied at a community college? It sounds worthless.

 

"Current systems use some basic radio protocol (or none at all) to manage the Flashes."

 

If there were no protocol as implied in parenthesis, this would likely break numerous laws.

 

"The system is easy to configure and use, the radio connection is basically an invisible wire."

 

This is false, it's a modulated signal.

 

"WiFi is a significantly more complex radio protocol, its no longer an invisible wire."

 

WiFi is more of a trademark than anything, meaning "a facility allowing computers, smartphones, or other devices to connect to the Internet or communicate with one another wirelessly within a particular area." 

 

"It may not be suitable"

 

It is suitable. 

 

"robust data transmission, not realtime flash control."

 

2.4ghz in a mouse, flash, drone, etc, is technically not realitime. Define robust?

 

"It could be possible"

 

You sound vague, unclear or to put it bluntly, uneducated.

 

 

As a hobby project, I bought a raspberry pi, attached a screen and created different lighting effects and colours from the screen. It's not very bright but for the odd job it's pretty fun. I'm able to make the screen flash and guess what network it uses!? Your beloved wifi

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The protocols used in Wi-Fi communications, adhering to the IEEE 802.11 standards, are designed to facilitate the movement of digital data. Handshaking is involved to move the data packets. That likely would cause a latency which could delay flash triggering to the point of producing partial exposures.

 

The frequency band over which the various flavors of Wi-Fi operate is not as relevant to suitability for on-time flash triggering as is latency. Also, in a noisy radio environment, latency will likely increase because of error-corrections and potential re-transmissions.

 

See http://en.wikipedia.org/wiki/IEEE_802.11for way more details than necessary. :-)

 

Simply, Wi-Fi is designed for an entirely different purpose not including real-time triggering.

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Yes, once a upon a time I could calculate the antenna length for a particular carrier frequency. Its not so hard to do, I still have the textbook, however these days data transmission is very very advanced and the manufactures usually specific the antenna design to use so it is no longer necessary to do the calculation in most cases (unless you are the antenna designer).

 

A modulated signal is exactly what is sent over the radio. That signal may be very simple (on/off), a little bit more complex (TTL) or even a little bit more complex (the canon system which allows for grouping flashes). But that is no different than a physical wire - when a signal is sent over a wire that too is a modulated signal. I'm not sure any of those qualify as protocols, perhaps TTL and systems similar to the Canon system should be considered as such.

 

 

Basically, every signal transmitted is a modulated by definition - you can learn about that here: http://en.wikipedia.org/wiki/Modulation

 

And its also possible to get some basics about protocol design here: http://en.wikipedia.org/wiki/Communications_protocol- its not light reading ...

 

 

It could be possible, as in it could be possible. However we must realize that WiFi was invented to make it easy for people to send messages between computers, and Raspberry Pi's, over a wireless network and not to trigger flashes. Its nice that you think its easy, hundreds and thousands of electrical, transmission, computer, integration and software Engineers/Managers/Testers/Supporters worked very hard to make it just that easy  B)

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As a hobby project, I bought a raspberry pi, attached a screen and created different lighting effects and colours from the screen. It's not very bright but for the odd job it's pretty fun. I'm able to make the screen flash and guess what network it uses!?

 

I can also suggest a cool hobby project  ;)

 

  1. Get a second Raspberry Pi and a flash extension cable. Cut the cable in half.
  2. Connect one half cable between the Camera and the Raspberry Pi. You will need to figure out the Pinout of the flash mount and connect the wires to one or more of the analog (or digital) inputs of the Raspberry Pi - which depends on your design.
  3. Connect the other half cable between the Flash and the second Raspberry Pi. Similar pinout and wiring will apply.
  4. Setup your WiFi connection between the two Raspberry's.
  5. Implement software on the camera Raspberry Pi to read the flash signal coming from the camera, convert it to an Application Level protocol, send it over WiFi (probably using UDP broadcast packets).
  6. Implement software on the flash Raspberry Pi to decode the incoming Application Level protocol and "play back" the Flash signal from the camera to the connected flash.
  7. Extend support for TTL, which might require communications from Flash to camera.

You might need a Scope to learn the TTL signal, and how to encode/decode it. But otherwise you could build this with hobby parts. I have personally  wondered if such a design would work for TTL (sans WiFi of course) since so few camera flash systems seem to support TTL, a generic solution would be very interesting for a product!

 

Its not so hard to do the prototype, turning it into a product could be more difficult.

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