Pixel TR-331 Wireless TTL Flash Trigger Review


By now it’s no big surprise that whenever the Strobist community at www.flickr.com discovers (or even gets a whiff of) any emerging products that have something to do with the subject of off-camera lighting, they jump all over it like nothing else I or anyone else has ever seen. The phenomenon of the strobist pile-on is really something to behold. The latest product to grab everyone’s short attention span is the Pixel TR-331 for Nikon iTTL flash units and TR-332 for Canon eTTL flash units. Trying to discuss Nikon and Canon flashes at the same time tends to make my head spin so I am going to restrict my comments to the Nikon flash version. I am a Nikon guy and the Nikon triggers are what I will be working with. The Canon version of this trigger is rumored to be coming in December 2009 or January 2010.  You’ve got to love rumors…

I will begin by saying that I have no affiliation with Pixel Corporation who manufactures these units and that I have no plans of becoming a North American distributor, spokesman or product model for their company. In fact, the first time I heard of Pixel was the discussion about their new TR-331 wireless flash triggers in the Strobist group on flickr.


In the early part of that thread the rumor was that these triggers where being sold only to distributors in lots of 100 and that the retail cost of a transmitter and receiver set might be somewhere around $200. I contacted Pixel to inquire about getting a set (or sets) to test; I was told in very clear terms (that lost absolutely nothing in translation) that Pixel does not send, lend or loan hardware for testing and that anyone interested in testing them would have to buy a set at whatever they determined the retail price was going to be. As I mentioned over on the strobist discussion, I wasn’t particularly thrilled with the idea of being a wireless trigger test monkey or in putting up hard cash for unseen and untested hardware and that’s based on my previous experiences with “value priced” remote triggers.  Here is a link to the Pixel product page:


In the rapidly moving world of off-camera lighting a person tends to get bored quickly, which often leads to rash decisions that usually involve throwing caution to the wind and doing the exact same thing that you had just sworn only moments before that you would never do. Just be aware that whatever follows is strictly my personal opinion and not intended to sway you one-way or the other. You have to decide for yourself if these particular wireless triggers will serve your particular needs or not.

Receiver, transmitter and studio flash cables.
Receiver, transmitter and studio flash cables.
It's all about communication.
It's all about communication.

I now have one set of the TR-331 triggers in my hands. I have been asked by Pixel not to discuss direct pricing or what I paid for these triggers, which seems reasonable since Pixel currently appears to be in the process of working out the pricing and distribution details with distributors in various countries. I don’t know if they are planning to sell directly to consumers or not, so I’m not going to speculate about it and will just move on to the review or what I like to call…

The Tao of Wireless Flash Triggers

Enter emptiness; it is the space where there is nothing that the usefulness depends.


Unfortunately I can’t begin talking about “The Way” without first talking a little about the how Nikon flash works in general (or at least my understanding of how it works). So be patient.


The Pixel TR-301 (Nikon mount) is a remote flash trigger that essentially uses radio signals in place of a hard-wired hot shoe sync cord such as a Nikon SC-28 TTL.


In case you didn’t know, TTL means “Through The Lens.” The lower case “i” in iTTL stands for intelligent.  When any iTTL compatible Nikon flash like an SB400, SB600, SB800 or SB900 is used in the on-camera hot shoe, the output of the flash is measured by the camera metering system and the exposure is adjusted on the fly. At least that’s the simplified version of the story we use to explain it to small children.  It’s not so much that using flash (even automated flash) is too far above our understanding, it’s just that there are so many things to talk about and people tend to get lost halfway through the discussion, which usually breaks down into a back and forth debate that leaves people wondering why they should even care. Oh, we care… and we care until it hurts.

First let’s look at what happens when we fire a Nikon flash directly from the hot shoe of a Nikon camera that supports TTL.

  • The on camera flash fires a pre-exposure sequence
  • The camera metering system measures the reflected light in the center of the frame based on the pre-flash sequence and calculates the power for the flash
  • The power level for the flash is adjusted based on any flash compensation that is set on the camera and on the flash, This adjustment also includes any exposure value (EV) compensation set on the camera
  • The shutter opens and the flash fires

As you can see there are at least three things you can adjust to affect the exposure. And when I say affect, what I really mean is screw up. Now that we have a basic idea about how TTL flash exposure works with a flash sitting on the camera hot shoe, it seems simple enough to extend the electrical connections between the camera and flash unit by using some sort of compatibly wired cable. I am using a Nikon D300; if you go online you can look at the D300 manual and read about optional flash units (Speedlights) beginning on page 357.


On page 362 you will find this interesting bit of information:

“When an SC-series 17, 28, or 29 sync cable is used for off-camera flash photography, correct exposure may not be achieved in i-TTL mode. We recommend that you choose spot metering to select standard i-TTL flash control. Take a test shot and view the results in the monitor.”


Hmmm… It’s suddenly clear to me how I came up with that “Test Monkey” concept. Even though I am using intelligent TTL flash photography it appears I am still going to be “chimping” my exposures as I go. For those of you who may not be familiar with that term, it is defined here:


In my mind a wireless remote system that is designed to replace a dedicated TTL hot shoe cord is not going to perform any better or in theory behave any differently than the cord with the exception that it essentially gives us a longer, cordless cord. What I want you to remember is Nikon’s advice about trying spot metering because it makes a difference depending on where and what you are photographing.

Off-camera flash photography or “Strobism” is commonly done using a camera in manual exposure mode in order to allow control over the balance between existing or “ambient” light and the artificial light produced by compact battery-operated strobes. Because of the relatively short duration of the light from a strobe unit the ratio of the two lighting types can be controlled by adjusting the camera’s shutter speed and aperture. Another thing that controls flash exposure in manual mode is the power level of the flash being used (and the flash to subject distance). Simple dumb wireless triggers are fine for firing flashes but don’t have any way of adjusting the power level settings remotely. You have to walk over (or climb up to) the flash unit and set the power level manually. On Nikon DSLR cameras with built-in (pop up) flash units you can set the power level of remote off-camera flash units using the built-in flash to send command signals to the off camera units (slaves) using the Nikon CLS (Creative Lighting System). That system uses pulses of light or pre-flash sequences of light to send information to the remote slaves. The CLS system works very well with two minor exceptions; the range is somewhat limited and the remote flash units need to have a direct line of sight to the on-camera commander flash, in order to receive the exposure instruction signals.  You might be able to cheat slightly on the direct line of sight limitation indoors where there are walls or ceilings for the pre-flash signals to bounce off of.

You are probably thinking or maybe hoping that the TR-331 units will extend that CLS function by transmitting these signals to the remote flash units in the same way as the built-in flash on the camera does but of course you cannot use the pop-up flash when the TR-331 transmitter is in the hot shoe of the camera because the pop-up has to be up to work. No pop-up flash means there are no in-camera controls to adjust the power level of the remote flash units in CLS mode. You might also think, or hope that you can still use the pop-up flash by simply plugging the TR-331 into the camera’s pc sync port. You can forget that plan because the sync port is disabled whenever the on-camera flash is raised.

When you have an SB800 or SB900 flash unit in the hot shoe of the camera they can behave as commanders for remote slaves just like the built-in flash with the added ability to control a third group of remote flash units. Since the TR-331 does not have a hot shoe on top of the transmitter, you cannot directly attach a flash to it to act as a commander for other off-camera flash units. So you have this long wireless wire but if you wanted to adjust the power level on the master or slave units you will need to walk over to the master flash on the TR-331 receiver and adjust it from there. While an SB800 flash operating in Nikon CLS allows you to set your remote units to several groups and adjust those groups to different power levels independent of each other, the TR-331 only appears to support one group consisting of one flash on a receiver set to MASTER and one or more flashes on receivers set to SLAVE. You can set the exposure compensation of the remote MASTER from the flash menu on the camera since I currently have only one RX unit so I was not able to test what affect adjusting the flash compensation (on the camera menu) has on the RX units set to SLAVE. There are no power level settings or adjustments on the TX or RX units and the flash adjustments on the camera menu are limited to those that would normally be available if the flash were on the hot shoe of the camera. Basically that means red-eye reduction, slow sync, rear curtain sync (I’m not 100% sure about this one) and flash compensation settings. There are no CLS group settings available on the camera when the built-in flash is not deployed.

Nikon CLS is not just about TTL metering but also about the ability to adjust the output or power ratios of separate groups of flash units. Because the TR-331 only has one available group you cannot use it to adjust ratios between groups remotely. Because the normal pre-flash does not appear to be used for TTL calculations with the TR-331 trigger, the flash appears to be dumping full power or close to it each time it is fired by the wireless trigger.

In general practice I have a lighting ratio in mind when I set up my off camera lights but my first best guess is often wrong and I have to lower the light stands, adjust the power and then reposition the lights. If you are shooting a live subject who is doing you a favor by posing for a photograph they usually get impatient very quickly and all this required fiddling with power levels is no help. I can understand why a lot of photographers are looking for a way to remotely control their lighting from the camera because more convenience generally translates into more productivity. I think they may be slightly disappointed by what I have to say next…


When I access the [remote, master, master (rpt), remote, su-4] menu on the Nikon SB800 flash I notice that as soon as I put the flash in the hot shoe of the TR-331 (turned on or off) that the master and master (rpt) menus went away and also that the A/AA menu option went away. To me this shows that the CLS functions are not supported when used with the TR-331.

I also tested to see if I could determine if the transmitter fires a pre-flash for exposure calculation in TTL mode. To do this I set the flash to rear sync mode on the camera menu and chose a shutter speed of around 1-1/2 seconds. The idea is that if there is an exposure metering flash (pre-flash), it will fire at the beginning of the exposure and then the flash will fire a second time (rear sync) at the end of the exposure. Flash, open shutter, flash, and then close shutter. Sounds good but it does not seem to work. I only get one flash. The TR-331 manual states the following:

[i-TTL] capabilities support various parameters through the camera flash setting, including exposure compensation, FV lock, anti red-eye reduction flash mode / anti-red-eye reduction slow sync, rear-curtain flash sync, site the ISO sensitivity, power zoom functions and so on.


The red-eye reduction flashes do seem to work though a lot of people are not wild about using that feature because it seems to make people blink before the actual exposure. The power zoom feature also works but it seems this would only be useful for those times when the remote flash unit was the same distance from the subject as the camera. I don’t think this would normally be the case except perhaps in a studio situation. For situations where the camera is much farther from the subject than the flash you will probably want to set zooming flash heads to manual and then adjust them according to your creative desires. I tested this and when auto zoom is on it makes the flash nuke the subject because it naturally assumes you need more power the more the flash head is zoomed to match the focal length of the lens being used. This distance information seems to work well on the TR-331. How useful it is will depend on what type of photographs you are trying to create.


The transmitter (TX) and receiver (RX) units have slow flashing red LED lights to show when they are powered on. This is very handy because the RX display is hard to read when a flash is mounted on it and there is no test button on the RX. Any time the two units are communicating the LED lights change from blinking red to rapidly pulsing blue. This blue flashing can go on for a relative long period of time. For instance, when I power up the camera it takes approximately six to eight seconds before the blue pulses stop. If that is the actual amount of time needed to alert the remote flash to exposure or mode changes then I would be concerned when shooting fast moving subjects. You might find yourself waiting on the flash a lot or taking time to take numerous test shots to see if the adjustments really updated on the remote flash. Both the SB600 and SB800 flash units seem to wake-up right away when you lightly press the shutter button on the camera.

The TX and RX units have battery level indicators on them, which is a nice feature. It may also alert you the fact that the battery is not seated fully in the TX or RX, even though other functions seem to be working. In fact the digital displays are very nice in general and a big improvement over tiny DIP-switches that are often difficult to change with just your fingers. Hold the power button down for two seconds and the TR-331 units spring into action with a little animation Pixel logo. The previous channel settings are retained from when the unit is turned off, which means you are not forced to constantly set it back to what you want. There is also a backlight on the display that is activated when you briefly press the function button. That’s neat. The function settings work just like a digital watch. Hold the button (or buttons) down for a couple of seconds to access the modes and channel settings. It’s simple and it works well.

TTL flash exposure compensation from camera menu.
TTL flash exposure compensation from camera menu.

When using the TR-331 for multiple flash setups, the first flash is designated the master and all other flashes are slaves. This means that you set the first RX to MASTER and then set all the other receivers to SLAVE. Because I only have one RX unit at this time, I have not been able to determine exactly how this affects the function of the units and speculating about how they might work seems pointless. The RX in SLAVE mode did seem to wake-up when the camera with the transmitter was turned on but it would not fire.  After way too many test shots in different metering modes, I can say that the Auto FP (high speed sync) seems to work (I only tested it up to 1/2000th of a second so far).

The MANUAL mode is primarily for studio flash units or other flashes that are not Nikon TTL compatible. The TR-331 set ships with a couple of decent looking cables for using them with studio flashes. I got fairly reliable results when I used the triggers in manual mode but I have had numerous issues with the TTL mode because the flash appears to fire before the shutter is fully open (I can see the flash fire in the viewfinder).

I have replaced the batteries in the TX and RX with new ones and I am still having issues with flash sync. At this moment I can detect 20 individual wireless networks in my building. During the day when I am near a window I have detected as many as 40 at one time. I’m going to try testing the TTL mode again tomorrow from a different location. Switching channels did not seem to increase the reliability. It is possible that I have the units too close together and this is causing some sort of feedback or interference as well.

When I have managed to get the flash and shutter to sync using TTL mode it works pretty well and I can adjust the flash output by using the exposure compensation available on the camera. I tried testing sync with my trusty old D70 and had the same issues. I just wanted to rule out that I had somehow fried the hot shoe on the camera by possibly frying another camera.

Shooting in manual mode.
Shooting in manual mode.

In short, I like these units a lot though they may fall short of wish list of features that many photographers are currently hoping for at a price they feel they can afford to pay. At the moment they don’t seem to be working as reliably as I would like them to but I’m willing to give them the benefit of doubt until I can at least determine the source of the problem. There are a lot of things I like about the TR-331. It’s going to ultimately come down to features versus cost factored with reliability and performance. Even after establishing any sort of benchmark for reliability it is going to be prudent to have back-ups when something breaks.

The main point to remember with any sort of light metering system is that you are not going to be able to randomly set up lights, blast away at full power and then have some sort of automation solve every lighting problem for you. Automation only works up to a certain point and TTL metering cannot fix huge errors in lighting exposure.

I’m not done yet; I’ll have more thoughts on the Tao of Wireless Flash Triggers very soon.

27 Replies to “Pixel TR-331 Wireless TTL Flash Trigger Review”

  1. Thanks for the review! I have a few questions:
    1. It’s interesting that as soon as you put the SB-800 flash in the hot shoe of the TR-331 (turned on or off) that the master and master (rpt) menus went away and also that the A/AA menu option went away. Were both RX and TX set to TTL mode and was the RX set to MASTER before you mount the flash? If there’s absolutely no way to have the master menus enabled when the flash is mounted then this could be a deal breaker.

    2. At first your test for TTL mode using rear sync and 1-1/2 second shutter speed seemed to fail (you only got one flash). But later you “managed” to get the TTL mode to work: how?

  2. 1) Yes, TX and RX both set to TTL and TX set to MASTER. I think that many people including myself were hoping that MASTER was a loose translation of COMMANDER. Unless I am somehow mistaken that is not the case. TTL appears to be controlled by camera flash exposure compensation only. On my D300 that is -3 stops to +1 stop.

    2) Nikon TTL metering is supposed to work by firing a pre-flash burst that is measured by the camera (or flash) meter and the flash power level is adjusted prior to the second flash to expose the image. So far it looks like the flash is only firing once which means there is no information provided to calculate correct exposure.

    I got the TTL mode to work randomly, usually by turning off the TX and RX units and then restarting them. In other words they are pretty erratic. The first thing I did was install different (new) batteries. That did not solve the problem. My other thought is that RF interference may be causing signal errors from the TX to the RX. The other possibility is that one or the other of the units is defective but I have not reached any solid conclusion yet.

    In TTL mode I am able to switch from TTL to TTL BL and FP HSS flash modes. There is communication going on in TTL mode. The big problem is with the flash syncing with the shutter.

  3. Good decision to wait. Other manufacturers will follow soon, hopefully with better pricing and reliability.

  4. Someone was asking which flashes I used for testing. I have one sb800 and two sb600 flashes that all seem to have the same issue with proper sync when used with the Pixel TR-331. I think other photographers are beginning to report the same sort of issues and this problem is currently being investigated by the manufacturer.

  5. Thanks for the time and effort you’ve put into sorting through this. Based on all the buzz on Strobist, I really had been thinking about pulling the eBay trigger. Now, though, I think I’ll give LPA (the PocketWizard people) a little more time to see if they can get their act together on the Nikon version of their ControlTL concept.

    The fact that it has taken them so long (and they still don’t have Nikon units out the door) suggests that there’s a lot going on “behind the curtain” in Nikon iTTL, and maybe it’s not realistic to expect Pixel to get all the functionality sorted out on their first try. It’ll be interesting to watch what progress they make, and the units probably will serve some people’s needs as-is. But I’m the type who gets frustrated easily, so what I think your experience is telling me is that I’d be better off waiting longer and spending more money to get something that absolutely positively will work (kinda like the experience I went through with generic eBay flash triggers before I wised up and sprang for PocketWizards…)

  6. Thanks for commenting. I was playing with these again today after reading some of the recent comments on flickr. The flash set to Master does seem to communicate the exposure compensation back to the camera because it shows up in the exif data file. That seems to confirm the latest report that there is actually two-way communication going on between the TX on the camera and the RX on the flash. Pixel told me in one of their emails that the Master RX and Slave RX do not talk to each other which is something I think would be required to have fully functional CLS.

    Reliability is the name of the game and there is no point adding on extra “features” if the trigger can’t fire the flash in sync with the camera shutter. I think they will get it right in the near future but we will have to wait a little longer.

    If you value your time, the PocketWizards start looking more and more reasonable.

  7. This unit falls way way way short of the PW Flex & Mini on features. Just wait till the Nikon units come out for the PW Felx/Mini’s. You won’t care how these units are.

  8. Still no sign of the Nikon version of the Flex & Mini. I’m looking forward to seeing those.

    Not everyone can afford Pocketwizards for casual use and the Pixel units are not the least expensive option out there either. Each person will have to decide on their own needs and budget. Recently I have been using the Yongnuo RF-602 wireless remotes with good success for manual off-camera flash work.

  9. Hello:
    Please sorry but I dont Speak English very well.
    The Pixel TR-332 for Canon have interference problems like the PocketWizard with Canon Speedlite 580EX II.
    The following E-Mail was sent from Ms. Antonella on Pixel to my partner Egibaud in Canonistas.com
    Dear Eric,
    We’ve tested the device with Canon 580 EXII. Our product also have some interference problems as PW, however, it can be avoid through set different frequency channel. We have 15 selectable channels.
    As I know, there’s no any review of our new product at present.
    Any of your suggestion will be appreciated.
    Best regards
    I have sent three E-mails to Antonella but I don´t have received any answer. Copy bellow:
    Dear Antonella:

    Many thanks for your reply.
    I need to know the prices for one transmitter and two or three receivers.
    Please inform if you have Free Shipping to Argentina and if you can ship as a Gift Item or invoiced under U$S 30.00.
    How many days will delay the shipment to Argentina. Have your shipments a Tracking Number ???
    I will use the transmitter with my Canon EOS 50D and I will use two receivers with Canon Speedlite 580EX II and one receiver with Canon 430EX II. Can you please inform if your TR-332 model is tested with this equipment ???

    I know that the PocketWizard triggers have interference problems with Canon Speedlite 580EX II and I need to be sure that yours flashguns TTL triggers will not present the same problem with my 580EX II and 430EX II and it will work fine with my equipment.

    Please sorry for all that questions and please sorry but I don´t speak English very well.

    Many thanks and Best Regards:
    In a previous E-mail sent to Antonella I ask about the TR-332 Canon availabillity and she confirm that this are available now.

    Please sorry for my english. I read your comments and I posted this just only for your information.

    Matias from Argentina.

  10. I am looking to use one of these units to illuminate a bungy jumper at night, and being able to adjust the flash intensity is important. From the photographer, we want to be able to change the intensity of the each flash, and have them fire one after the other, so image A and B of the sequence are from flash 1, and image C and D are from flash 2, so you end up with 4 sequence shots of the jumper in the air, and all illuminated correctly.

    Distance is at least 15 meters.

  11. I don’t have an answer to that at the moment. You may want to send an email directly to Pixel support.

  12. I have a set of 1 TR-331RX transmitter and 2 recievers.
    I can make one transever work reliable, but struggle to get 2 working at the same time, once 1 reciever is icnnected the second one seems to be disconnected for 9 out of 10 shoots.
    This iss ue is the same for TTL or Manual, has anyone experinece with this 2 receivers setup of the TR-331RX and woudl have recommendations?

  13. A stupid question. I want to pass to wireless triggering simply to work more conveniently with long exposures (no flash) at night. Will this type of triggers be useful for the purpose? If not what could you experts recommand?

  14. The Pixel trigger would not be a good choice because there is no way to activate the transmitter except from the hotshoe of the camera (no test button).

    The Yongnou RF602 is a good remote trigger but not for long exposures because you would have to hold down the trigger button for the whole exposure.

    The Photix Cleon works very well if you don’t need to use it over a long distance. I have not tested it for signal range.

  15. The set I bought has the same problem mentioned in the review in that it seems the flash goes off before full opening of the shutter. I see half bright and half darker images randomly. Is there a fix for this?

    I first thought it was down to the sync but even after lowering it to 1/160 or 1/125, I still see this “band” across my images (around 1 or 2 pictures for every 10 shots).

    Wasted so much money on wireless triggers, is there even ONE that can do the job properly without giving any problems at all? The above replies mentions interference problems with the 580 EX II, so I can forget about the pocket wizard.

  16. Good morning!
    Yesterday I received my kit TR-331 RX / TX. I also noticed that it does not work in i-TTL power to change the shooting of my SB-910.
    Do you know which model supports the Nikon CLS system? I found the website: http://wiki.pocketwizard.com/index.php?title=PocketWizard_Wiki:Books/MiniTT1_and_FlexTT5_Manual/. Do you know? For me to buy it is a bit tricky in terms of Brazil’s tariffs, the price is expensive!
    I really enjoyed your explanation about the TR-331! Already knowing that I test have to adjust the power via the “Flash Mode with Auto Aperture” or “Manual Flash Mode”. God bless you and yours!

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