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Radio transmitters for remote flash
Table of Contents
- Introduction
- Legal Issues
- Compatibility
- Technical Specifications
- The Product
- Connections
- Tests
- Conclusion
- Link farm
Introduction
When it comes to battery operated wireless slave flash systems, PocketWizard is the top brand. With 500 meters (1600 feet) reach, two-way communication, and the ability to reprogram a hairlight located on a high boom from camera position, they provide very powerful capabilities. The downside of PocketWizard is cost, the top of the line MultiMax costs around $ 295, and the budget model, Plus is $ 165. There now exists low cost alternatives with a more limited range and without the bells and whistles. These are sometimes jokely known as Poverty Wizards.
The first of these to become available was a simple 4-channel radio slave made in China by Shanghai Jinbei Photographic Equipment Co., Ltd.. I first noticed it on eBay in the spring of 2005, but they can be found in regular stores as well.
Price vary widely between vendors. At eBay, you usually pay less than $30 for a transmitter/receiver pair (the actual amount vary from auction to auction), while Adorama charge $130 for a very similar item. The table below lists the sources I've found for these low cost battery operated slave triggers:
| Vendor | Store Id. | T/R pair | Receiver |
|---|---|---|---|
| Shanghai Jinbei Photo | YS-C | - | - |
| Magic_Trigger | YHDC-B | <$24 | - |
| NYcarolShop (Caroline Ho) | YHDC-B | <$30 | - |
| Auctionguru365 | YHDC-B | <$30 | - |
| Photoland168 | GT301-B | <$30 | - |
| Joe's Photo Auction | GT301-B | <$30 | $30 |
| Alzo | RT-01 | $74 | $47 |
| Speedotron | 23501 | $120 | $65 |
| Adorama | 11244 | $130 | $69 |
| Paramount Cords | DC-01 | $140 | $79 |
| Porter's Camera Store | RT01 | $160 | $100 |
Auctionguru365, Joe's Photo Auction and Photoland168 publishes very similar advertising copy, product photos and FAQ, and are probably connected in some way.
As far as I am able to tell, all the vendors sell a similar unit, from the same Chinese manufacturer. However, several versions exists. The initial receivers sold by Joe's Photo Auction did not have a pc-connector, the present version has. There also has been some changes to the trigger circuits, which means that older units may not necessarily be compatible with newer units.
The Shanghai Jinbei Photo also makes a AC-powered version (for studio strobes), a single channel version, and a 16 channel version. The AC-powered version and the 16 channel version has received favourable reviews from its users, while the single channel version has been reported to be prone to RF-interference from computer equipment and other electronic equipment such as washing machines. The different model types do not have any frequencies in common. The single channel model does not use any of the frequencies of the 4-channel models, and the 4-channel AC and battery powered models use a different set of frequencies.
The items reviewed in this article (one trigger and five receivers) is a 4-channel model designated GT301-B, and was purchased from Joe's Photo Auction in April 2005.
August 2007 update: The GT301-B that is the the subject of this review, appear to be no longer available, but a Hong Kong based firm, Harvest One Limited manufactures a similar 4 channel unit named Cactus One PT04 V2 that seems to have similar characteristics as the GT301-B (without being compatible). See Gadget Infinity for current price and availability.
Legal Issues
According to Joe's Photo Auction the GT301-B unit sold to customers in the USA uses the 315 Mhz band set aside for “remote keyless entry systems” (garage door openers), and the version sold to users in the European Community (EC) operates in the 433.92 Mhz band set aside by the European Radiocommunications Committee (ERC) for “short range wireless devices” (also garage door openers). It has an output effect less than 10 mW, well below the 25 mW limit set by the ERC. Some vendors (e.g. Photoland168) on eBay use phrases such as “Wireless RF-433” to characterise the EC version. I've also noted that the EC version is is usually listed on eBay with a price in British Pounds or Euros instead of US dollars.
Because of the different frequency allocations, use of the US version is illegal in Europe, and use of the EC version is illegal in the USA.
In a note contributed to my blog by rivan, it appears that the units do not bear an FCC label and has not been approved by the FCC. Until this has been resolved, they are illegal in the USA, as noted in the FCC daily digest for August 29, 2005:
JOE'S PHOTO AUCTION.
Issued an Official Citation to Joe's Photo Auction for importing and marketing unauthorized radio frequency devices in violation of Section 302(b) of the Communications Act. Action by: Deputy Chief, Spectrum Enforcement Division, Enforcement Bureau by LETTER. (DA No. 05-2352). EB DA-05-2352A1.doc DA-05-2352A1.pdf DA-05-2352A1.txt
Compatibility
Unfortunately, the model designation (Store Id. in the table above) is not a reliable mean to distinguish between the different versions of the 4-channel battery powered unit.
The EC and US versions uses different parts of the radio band, and are obviously not compatible, but both bear the same model designation.
The simplest way to ensure compatibility is to buy all the units you need with the same store id. from the same vendor at the same time. Otherwise, you will need to communicate with the vendor to make sure that the units you buy are compatible.
I looks like some vendors are becoming aware of the compatiblity issue. Auctionguru365, for instance, now includes the following advisory in their auction material: “Important Notice: YHDC-B is not compatible with GT301-B. If you are using GT301-B please mention this in your payment so that a GT301-B model will be sent to you instead.”
There are additional user comments about compatibility in my blog.
Technical Specifications
The trigger voltage of the transmitter is less than 6 V (my unit measured 4.96 V), which makes it safe for all modern digital cameras. According to the vendor, the receiver is capable of handling old strobes with high trigger voltage up to at least 200 V. It worked fine with my old Vivitar 283 that has a 107 V trigger voltage, as well as my Nikon SB-800 and my Canon 550EX (both has a trigger voltage close to 6 V.
According to the vendor, the unit is fast enough to work with shutter speeds up to 1/1000 seconds, for cameras with shutters able to synchronize at that speed.
The Product
Most of the text on the outside of the box is in chinese, and reads (thanks to peter for the translation):
Product Features: Microprocessor encode/decode; very good interference rejection ability; microprocessor controlled; long distance remote controlled; low trigger voltage and current; trigger current only 0.01 mA; will not hurt camera standby sleep mode; super low power consumption; long lasting battery; can standby for 1 year or trigger 20,000 times.
There is no manual included - just an one page “TroubleShooting”-guide. I had no trouble setting it up. After I'd loaded fresh batteries and connected the units, I was ready to shoot.
The units seem, however, to be sensitive to battery voltage. There is no “low battery” indicator. Run-down batteries give poor reliability and reduced firing range. If one experience problems in these two areas, replacing the batteries should be the first thing to try.
Operation is simple and intuitive. There is no on/off switch. The transmitter has a “test” button on top (which does what you expect), and the only other controls are two microswitches which selects one of four channels.
While being made from plastic, the unit appear to be of good quality and well constructed for the price. When I accidently dropped one of the receivers from a height of about one meter on to a hard, wooden floor, it broke open at its joins. However, there was no breakage and after I've reassembled it, it was as good as new.
Some users has reported that dry soldering has stopped units from working. Opening the unit up and resoldering dry connections has fixed the problem.
Below is a picture of the four items that comes with the basic kit:
The item on the left is the transmitter. It normally mounts in the camera's hot-shoe, but also have an 1/8" jack-plug socket for cameras without a hot-shoe. Included is also a 30 cm (12") cord with 1/8" jack-plug at one end and male pc-plug at the other. The item on the right is the receiver - it does not have a hot-shoe, but has a cable with a 1/4" jack-plug for studio strobes, and an 1/8" pc-socket for standard portable flash guns. The final item in the basic kit is a 1/4" to 1/8" jack-plug adapter.
The transmitter uses a 23A/LRV08 alkaline 12V battery (included) rated at 20 000 flashes. The receiver uses two standard AA/R6 1.5V batteries (not included) rated at 30 000 flashes.
Connections
The GT301-B can only be used to trigger the flash remotely. There is no way to remotely control flash power, as with the more expensive radio systems and Canon's E-TTL and and Nikon's i-TTL systems. This is an obvious limitation. If you use manual or vari-power flashes, you have to work out the exposure manually or by using a flash meter. If you want a complex lightning layout, you also have to walk around to adjust each flash by hand. If you take advantage of the flash' auto mode, the flash should in principle take care of the exposure for you, but my tests show that this not always the case.
The receiver is obviously constructed with monolights with 1/4" jack-plug socket connector in mind, as is evident from the non-detachable cord with a 1/4" jack-plug at the end. For standard portable flash guns, newer versions of the receiver sports an 1/8" female pc-socket at the back.
All exposed plugs are “live”, so with my Vivitar 283 hooked up to the receiver via the pc-connector, all its 107 volts appear at the exposed 1/4" jack-plug. This will give you a nasty shock if you touch it. For safety, you should put insulating tape on exposed plugs.
The images below show how to connect the receiver to a standard flash gun (as opposed to a monolight):
All my GT301-B receivers came with a standard 1/8" female pc-socket (depicted close up in the photo on the right above). If the flash has a cord with a male pc-connector, plug this into the receiver's pc-socket. The image to the left shows a Vivitar 283 connected to the receiver using this connection.
The pc-socket is not featured on the YHDC-B model.
If the flash does not have a pc-connector nor a 1/4" or
1/8" jack-socket, you need a simple two-contact shoe hot-shoe
adapter with an 1/8" jack-socket.
The image on the left above shows a set-up using
such a hot-shoe adapter. You plug the receiver's jack-plug into the
hot-shoe adapter by means of the 1/4" to 1/8" jack-plug
adapter. Joe's Photo Auction sells the hot-shoe adapter shown for $8
a piece. They work, but they do not appear to be very well
constructed, and may not last very long. You may be better off making
your own or - provided your radio trigger features a pc-socket -
getting a male pc to hot-shoe adapter as shown in the image to the
right above.
For monolights that uses a H-prong, Paramount Cords sells a 1/4" jack-socket to H-prong adapter.
Note 1: The Sigma 500/530 DG Super must be set to C0 SL mode (that is the normal slave mode) to be fired from a simple two-contact hot-shoe that is featured on most radio triggers. It will not fire at all in manual mode without a full E-TTL connection to the camera body. It can't be set to FP (high speed sync) or second curtain sync in C0 SL mode. The Sigma EF-500/530 DG ST does not have a slave mode, and can not be used as a slave flash
Note 2: Some newer Canon Speedlites, in particular 430EX and 580EX, fire at random with some versions of the Gadget Infinity radio triggers. The problem is fixed in a later model. Check out compatibility with your Speedlite before buying if you use one of these. There is some discussion about this in this thread on Flickr. It is long, but look for entries from RAitch between 201 and 300 (on page 3). Older Speedlites, like the 550EX and 420EX, do not have this problem.
Tests
All tests uses as its subject an ordinary indoor scene (my living room, which a nice white ceiling for bounce). The tests were conducted after dark, so that the flash was the sole source of light. I use the histogram in Photoshop CS to judge exposure.
Timing test
For my first, simple test, I used a vintage Vivitar 283 and a Canon Powershot G5 with a central shutter. The G5 was set up in manual mode, f=7.2mm (35mm FOV equiv.), ISO 100, shutter speed set to 1/250 second (the maximum flash synchronization shutter speed according to the G5 manual), and aperture f/2.8. The Vivitar was set to bounce against the ceiling in auto mode with an aperture f/2.8.
The GT301-B radio slave kit performed as advertised. The exposure was spot on. Lowering the shutter time resulted in identical histograms, which means that the unit is fast enough to keep up with at least a shutter speed of 1/250 second. Increasing the shutter speed beyond 1/250 second resulted in more and more underexposure.
I do not have access to a camera with a rated flash synchronization shutter speed faster than than 1/250 second. However, timing tests done by others indicate that the radio trigger is not fast enough to work with shutters up to 1/1000 second. These tests has been posted to the DPreview Lighting Technique Forum.
Dan Jeter, using a Nikon D2x with a focal plane shutter wich has a rated X-sync. speed of 1/250 sec., has posted test images that shows that setting shutter speed to 1/250 sec. results in a noticable curtain shadow, and that 1/200 sec. is the top speed that produces reliable results on a Nikon D2x. J.R. Sprawl, using a Nikon D70 with an electronic shutter writes: “With the radio slave, usable sync speed is limited to 1/640 sec. - at 1/800 sec. there is about a 1-stop exposure loss.”
Exposure tests
Again, I used the Vivitar 283 and Canon Powershot G5. The G5 was set up in manual mode, f=7.2mm, ISO 100, shutter speed set to 1/250 second and aperture f/2.8. The Vivitar was set to bounce against the ceiling, auto mode, and aperture f/2.8. As in the previous test, the exposure appeared to be correct.
I then changed the head position of the Vivitar to provide direct flash. This, however, resulted in a 1/2 stop overexposure with noticable burnt out highlights.
When testing a multiple slave setup, using a Vivitar 283 and a Nikon SB-28 (both set to auto, ISO 100, aperture f/2.8). I got similar results. With both flashes bounced against the ceiling, the exposure was correct. With direct flash, I again got around a 1/2 stop overexposure.
Conclusion: Auto does not always result in the right exposure. If you have the time, make a test shot and check the histogram. If necessary, adjust the exposure.
Range test
The units are not reliable if placed to close together. You need at leat two feet between two receives, or a transmitter and transceiver, to stop them from interfering with each other.
My range tests for long distance was conducted outside by setting the flash with the reciver attached on a tripod and then moving away from it. Distance was measured by counting paces (not a very accurate method, I admit). I found the unit to work reliable up to about 100 meters (300 feet). Beyond that, it became more erratic and stopped working altogether at around 200 meters (600 feet).
Indoors, I found it capable of working through at least three wooden walls, which is the maximum size of my apartment.
While its range is clearly more limited than PocketWizard (500 meters) it is also much better than its rated range (25 meters). I find the range it offers adequate for my needs.
For a more accurate range test, see this user report by FotoFlip posted in the DPreview Lighting Technique Forum. He uses GPS to measure distance accurately.
Conclusion
The GT301-B slave transmitter and receiver appear to be reasonably well constructed (for its price) and it works as advertised. The top synchronization speed is less than advertised, but adequate for most users. You may need to work with the histogram or flash meter to get correct exposure in some situations.
With fresh batteries, the units are fairly reliable, misfiring in about one or two instances out of around one hundered. With run-down batteries, reliability is significantly reduced.
In the connections department, the receiver is a bit of a kludge if you intend use it with something that does not have a 1/4" jack socket or a standard pc-connector. The 1/8" jack-plug to hot-shoe adapter works, but is not well constructed. You may want to look for alternatives, or even construct your own.
The main utility of this item is to let users of modern digital cameras use old, cheap and powerful auto flashes such as Vivitar 283 without having to worry about high trigger voltages damaging the camera. It also lets you move the flash unit away from the hot-shoe for more flexible lighting technique.
For complex lighting arrangements using multiple slaves it has obvious limitations, in particular when compared to more sophisticated and expensive flash systems. If you are a professional photographer requiring absolute reliability in all situations, this is not the solution. However, the price is nice (at least if you buy it off eBay). If you are on a tight budget, the low price may more than make up for its lack of bells and whistles.
Link farm
- User reports and ideas:
- Radio slaves: Mounting ideas, by Jean Bernier
- Wireless trigger distance tests, by FotoFlip
- Cactus PT-04 wireless radio-based flash trigger, by N.K. Guy
- Gadget Infinity V2 Wireless Flash Trigger, by L7 Foto
- Inconsistent firing outdoors, by Mudanoman1
- Next, They'll be Using Nitro, by Strobist
- Ebay radio Slaves, Strobist.com group @ Flickr
- User reports in my blog, by several users
- Other radio slaves:
- Alien Bees
- Bowens Pulsar
- Calumet
- Elinchrom EL-Skyport
- Gadget Infinity
- Hensel Studiotechnik
- MicroSync
- MiniMagic
- PocketWizard
- RadioPopper
- Quantum
- Zap-Shot
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