I am stumped, what is the purpose of this device - Page 1
Forum section: electronics / general

author: forthnutter
author_rank: Newbie
timestamp: June 17, 2018, 08:45:55 am
content: I have been stumped by what is the purpose of this product.It looks to have a photo diode on the end some resistors a capacitor, something that looks like a transistor and a socket.All encapsulated in some resin.Comes in a case with a special cut out.My first thought, it was some light sensing switch.Has anyone anything like this??.

author: ElektroQuark
author_rank: Unknown
timestamp: June 17, 2018, 08:52:30 am
content: A photo flash slave trigger?

author: forthnutter
author_rank: Newbie
timestamp: June 17, 2018, 09:07:05 am
content: Well I'll be,I learnt something new today.

author: glarsson
author_rank: Frequent Contributor
timestamp: June 17, 2018, 10:58:27 am
content: Are they still manufactured? No modern camera or flash still use that old connector. You could buy these over 40 years ago ...

author: ebastler
author_rank: Super Contributor
timestamp: June 17, 2018, 12:07:50 pm
content: Quote from: ElektroQuark on June 17, 2018, 08:52:30 amYes -- the "Syncro Eye", made by Nissin in Japan. Google knows about them if you want to find out more, or buy a used one for around $10. Neat little device; I like the vintage look!

author: djacobow
author_rank: Super Contributor
timestamp: June 17, 2018, 08:19:28 pm
content: Quote from: glarsson on June 17, 2018, 10:58:27 amStudio lights (even new ones) still have trigger inputs like this. Most studio lights have their own slave sensors, though. A complicating factor is that the modern hot shoe flashes actually send out an information-encoded pre-flash to other hot shoe flashes of the same make. As a result, you can control a bunch of slaves from the camera -- which is very cool, but it makes it harder to use "dumb" old studio flashes as they'll false trigger with the information pre-flash.

author: TimNJ
author_rank: Super Contributor
timestamp: June 19, 2018, 01:50:10 am
content: Quote from: djacobow on June 17, 2018, 08:19:28 pmAre you saying that new flashes operating as slaves receive encoded informationoptically, as in, with light, and not an RF link? If so, that's interesting.

author: Halcyon
author_rank: Unknown
timestamp: June 19, 2018, 03:04:03 am
content: Quote from: TimNJ on June 19, 2018, 01:50:10 amNot so much these days. Some of the older Canon Speedlite flashes used infrared to trigger off-camera flash units (there were sensors on the front and back of the flash). These days, RF is more common as you can do much more with them, like trigger them in "groups" or position the flashes out of sight of the camera, for example through doorways or hidden behind objects.Modern DSLRs (made in the last 10-15 years) also use RF to transmit images straight from the camera onto a computer as you take the photos so you don't have to dump them via a cable or card reader later.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 19, 2018, 04:44:16 am
content: Quote from: Halcyon on June 19, 2018, 03:04:03 amI haven't seen very many DSLRs with that feature, but there are SD cards that do just that.

author: Halcyon
author_rank: Unknown
timestamp: June 19, 2018, 04:55:29 am
content: Quote from: NiHaoMike on June 19, 2018, 04:44:16 amI suspect that it's built-in to the high-end cameras, but almost all the decent digital SLR's support it (with an extra attachment). I had an old Canon EOS 400D which supported it with an extra hot-shoe RF device.Even many sub-$500 point and shoot cameras these days are Wi-Fi enabled. I have a little Nikon I use for work which has it (although I've never used it).

author: tooki
author_rank: Super Contributor
timestamp: June 19, 2018, 06:12:09 pm
content: Quote from: TimNJ on June 19, 2018, 01:50:10 amI can’t speak to studio flashes since I have no experience with them, but Nikon’s Advanced Wireless Lighting (AWL) system, introduced in 2003, uses the xenon flash tubes themselves to send data to slave flashes (the slave flashes only look for the data in the infrared spectrum). For clarity, I shall henceforth use the brand name “Speedlight” to refer to the devices, and “flash” to mean an actual burst of light from the xenon tube.As best I can tell, the system works like this:1. The photographer presses the shutter release.2. The master Speedlight (which is either one built into the body, or one connected via the hot shoe), based on the settings you set in the camera menus, sends an initial optical data burst instructing all the slave Speedlights to pop a metering flash.3. The camera’s metering sensors observe the scene without and with the metering flash, to determine the amount of light the Speedlights are adding to the scene, and the camera calculates the correct exposure and flash settings.4. The shutter opens.5. The camera commands the master Speedlight to send another optical data burst telling the slave Speedlights their specific settings.6. All the Speedlights pop the exposure flash in sync.7. The camera waits until the selected shutter speed has elapsed.8. The shutter closes and the exposure is complete.When using rear-curtain flash sync, the order is slightly different, in that the step 7 moves ahead of step 5, such that the metering flashes still occur rightbeforethe shutter is opened, but the actual exposure flash pops at theendof the exposure.Because the second data burst (step 5) happens with the shutter open, then when a) shooting at very, very close range, AND b) using a built-in Speedlight as the master, AND c) manually setting said built-in Speedlight to “off” (i.e. “please don’t contribute light to the scene!”), the data burst will cause slight unwanted light in the image. Nikon actually sold (sells?) a little IR filter to dangle in front of the built-in Speedlight, to permit the data burst in IR to pass, but blocking the unwanted visible light.And all this happens literally in the instant between pressing the shutter release and the shutter opening, which is something like 1/10 second perhaps (it feels instant in practice), assuming focus lock was already achieved and the Speedlights’ capacitors are charged.The system allows for 4 channels (so different photographers don’t step on each other’s toes), and within each channel, 3 groups of Speedlights. So assuming a camera body with a built in master-capable Speedlight, it means you can individually set the flash exposure (manual, auto, auto+compensation value, and trick features like repeating strobe, in some models) for the built in Speedlight and for each group of slave Speedlights. Each group, in turn, can have as many Speedlights as you want.I own 4 such Speedlights and often use one on-camera and let it control the other 3. So I can do backlight, side light, etc with quite fine control of each Speedlight to compose an image.Now, in the past year or two, Nikon released an RF version of AWL, which they are imaginatively calling Radio-Controlled Advanced Wireless Lighting (“radio AWL”). I haven’t had a chance to use it. I’m not entirely sure what problems it solves, since the xenon/IR optical system works so very well (in my experience, you have to really work to make a slave not see the commands, it works fine around corners and stuff - the IR receivers must be very, very sensitive!). The only thing I can imagine it adding is feedback on the slave flashes’ charge status, which would let the camera know to delay shutter release until they’ve recycled. (Or let it go Canon-style and allow an exposure with incompletely recycled flashes, compensating the reduced lighting through ISO change or something.) But because radio AWL remains compatible with optical AWL (in that both can be used simultaneously, since all radio-AWL-capable hardware is also optical-AWL-capable and allow mixed use), I suspect that little, if anything, has changed beyond the actual communication medium.Of course, now this has me curious as to what the data packets look like, etc. Maybe someday I’ll lash up a phototransistor to my scope and see what I can find, assuming nobody else has done this already...P.S. It just dawned on me that Nikon uses the word “commander” for what I’ve called the “master” above. I think I can’t be bothered to edit it all. I don’t think this affects clarity, other than knowing what it’s called in the camera menus.

author: djacobow
author_rank: Super Contributor
timestamp: June 19, 2018, 08:54:19 pm
content: Quote from: TimNJ on June 19, 2018, 01:50:10 amYes, exactly that. In shoe-mounted "speedlites" it was quite common. RF is taking over the space, but optical was a thing, still is for the flashes in my bag. :-)

author: Dubbie
author_rank: Unknown
timestamp: June 19, 2018, 09:24:18 pm
content: That connector is not a good one at all.I have had problems with them over the years. The contacts for the center pin spread easily with off axis wiggling and after a while no longer contact the pin anymore.More that once I've had to give the plug pin a tweak to deform it so it makes contact in the middle of a shoot. Kind of an emergency solution because that only makes the socket worse.

author: impulsite
author_rank: Newbie
timestamp: June 05, 2020, 02:21:59 pm
content: Better late than never.The circuit of this photo flash slave trigger is very simply.

author: westfw
author_rank: Super Contributor
timestamp: June 09, 2020, 10:15:08 pm
content: There used to be a device called as LASCR - Light Activate Silicon Controlled Rectifier. You could build a "Slave flash trigger" from an LASCR and a resistor, and it was a circuit that appeared in many hobbyist books and etc. Most surplus stores and I think even Radio Shack sold them. I see there are still tutorials on the web about these, but I haven't seen any for sale in a long time. (And I never knew what their "original" application was, that allowed them to be sold "surplus." It seems unlikely that "slave electronic flash trigger" was a big enough market, given that these things appeared well before electronic flashes were common...)

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 09, 2020, 11:16:13 pm
content: Quote from: westfw on June 09, 2020, 10:15:08 pmThose are still common as part of SSRs. There's just next to no demand for the optically triggered thryistor by itself.