Backscatter TTL Flash Trigger Review

When Backscatter launched their impressive Hybrid Flash (HF-1) back in April 2024 (see my comprehensive review), they also announced a couple of forthcoming accessories. One of them was an optical TTL flash trigger, designed to provide very accurate TTL control of the Hybrid Flash for Sony and OM System/Olympus cameras. Fast-forward to February 2025 and Backscatter unveiled three different flash triggers:

1. the Backscatter Smart Control TTL LED Universal Flash Trigger for OM System and Olympus, meant to fit in housings by a range of brands;
2. the Backscatter Smart Control TTL LED Universal Flash Trigger for Sony, also designed to be compatible with a variety housings;
3. the Backscatter Smart Control TTL LED Nauticam Flash Trigger for Sony, custom designed to fit in Nauticam’s housings for Sony full-frame cameras.

Over the last few weeks, I have spent more than 60 hours shooting the third trigger on a Sony Alpha 1 in a Nauticam housing with a pair of Backscatter Hybrid Flash strobes. This included over 40 dives in the eventful waters of Raja Ampat, Indonesia, and the rest in temperate waters, around Sydney and South West Rocks (NSW, Australia), using a mix of macro and wide-angle lenses.

Whilst I haven’t tried the other two models, I expect my observations of the Sony/Nauticam version to be very much applicable to these TTL triggers.

Review Index

• Form factor and functionalities
• Why shoot TTL?
• TTL accuracy
• Switching to manual
• High Speed Synchronisation
• Burst shooting
• Trigger battery life
• Strobe battery life
• Final words
• About the reviewer

Acknowledgements

I would like to thank Backscatter for providing the Sony Alpha 1 camera, lenses, housing, ports and Backscatter Smart Control TTL LED Nauticam Flash Trigger for Sony used in this review, and Papua Diving for their hospitality on Raja Ampat’s beautiful Kri Island, as well as Fish Rock Dive Centre for some great diving in Australia’s South East.

This article was first published in DivePhotoGuide, in April 2025.

Form factor and functionalities

The Backscatter Smart Control TTL trigger is a small device with a built-in rechargeable battery, rated for 13 hours of use. It comes with an on/off switch (mine has been “on” for six weeks at the time of writing), and two LEDs. The blue one is the status light, which blinks to let you know the device is on, while the green one is the battery indicator, which blinks once per 20% charge, so five blinks mean 100% charged.

The two “Universal” versions of the trigger have fiber-optic adaptors attached on small cords, which plug into the housing’s fiber-optic ports inside the housing. The Sony/Nauticam version I tested has a sleeker design, with two LEDs pointing up, attaching straight into the two fiber-optic connectors inside the Nauticam housing. Whenever it needed charging, I simply had to slide the trigger off the camera’s hotshoe; no need to disconnect cables, nor even pull the camera out of the housing.

To use the trigger in TTL mode, you need to move the Hybrid Flash’s mode dial to either the “SC” or “SC Macro” position (the latter being for close-up, smaller subjects), and pick the right setting in your camera’s menu. On Sony cameras, this requires changing the “Wireless Flash” setting from ON to OFF—I have set this as a shortcut on the camera. Changing “Wireless Flash” back to ON lets you control the Hybrid Flash (and any other strobe) manually; you just have to remember to dial your strobe(s) back to manual mode.

Why Shoot TTL?

If you’re beginning your underwater photography journey, you’ll likely find TTL mode very useful, as it lets the camera choose the power of your strobes—meaning one less thing to worry about. Indeed, there are plenty of subjects and scenes where automated strobe exposure can produce beautiful lighting.

If you’re an experienced shooter, used to controlling your strobes’ power manually, going back to TTL mode is all about saving time by automating some of your lighting adjustments. When you can tell the scene doesn’t require running your strobes at distinct powers, then TTL mode saves you the effort of rotating the power dials (11 clicks from min to max power, on the Backscatter Hybrid Flash, for example). I rather enjoyed being able to switch between lighting up a scenic shot, and then a close-focus wide-angle subject, by simply moving my strobes closer or further away from the housing, knowing the TTL trigger would attenuate or boost their brightness as needed. As a result, I found myself swapping between subject sizes more frequently than I would otherwise do.

TTL mode is also great for subjects on the move, especially when their distance to you keeps changing unpredictably, with the risk of overexposing bright bellies—think mantas, sharks and turtles. In TTL mode, there’s just a greater chance of being ready for unpredictable encounters or erratic subjects.

TTL Accuracy

Before discussing accuracy, let’s first look at how TTL works when using your camera’s pop-up flash on land, or a compatible flash mounted on the hotshoe. Basically, when you pull the trigger, the camera produces a series of low-power pre-flashes, at various brightness levels, and assesses their effect on the scene. The camera then instructs the flash to fire for the actual exposure, at the power level that the camera determines will produce the right exposure. The whole process is very fast and the pre-flashes are hard to tell apart from the actual exposure’s flash.

By contrast, when underwater, TTL support has, broadly speaking, been offered in two ways, depending on the strobe brand/model:

• Option 1: Hard-wired electrical TTL. A circuit board, connected to the camera’s hotshoe, interprets the camera’s TTL instructions and communicates with the underwater strobe via an electrical cable, instructing the strobe on when to fire (pre-flahes plus actual exposure flash).
• Option 2: Slave Optical TTL. The camera’s built-in flash fires in TTL mode (pre-flashes plus actual exposure flash), the light of all these flashes travels through fiber-optics, to reach the strobes’ light sensor. The strobe then fires pre-flashes, trying to replicate the camera’s built-in flashes’ duration, including the actual exposure flash.

The general consensus is that Option 1 offers better accuracy but requires bulkier electrical cables. With fiber-optic cables being more widespread nowadays, most TTL underwater shooters are currently using some version of Option 2.

The Backscatter TTL trigger offers a third way: The trigger “speaks” with the Hybrid Flash via a digital optical protocol. Think of it as sending some zeroes and ones in the form of optical signals (like a Morse code), through the fiber-optics. Backscatter says this provides the same level of accuracy as Option 1 in transmitting TTL instructions while offering the convenience of lightweight, inexpensive and maintenance-free fiber-optic cables.

It would take controlled-environment side-by-side testing to confirm that claim versus other means of TTL control underwater, and while I know the Backscatter team has conducted extensive in-lab testing, reproducing such results goes well beyond the scope of this review.

What can I say is this: I found my two Hybrid Flash strobes consistently produced pleasing exposures when firing in TTL mode (“SC” on the mode dial) with the Backscatter TTL trigger. Shadows were cleared, colors were revived and overexposures prevented in all but the most complex scenes. I confidently used TTL as my default shooting mode throughout this review, only switching to manual power when the scene/subject required it—see the next section.

It’s worth noting the end result depends not only on the trigger’s TTL protocol accuracy, but also on the camera’s metering system, to assess the scene and decide on the right amount of flash light to send. I found the Sony A1’s “Multi” metering mode to be a good all-rounder option. I occasionally switched to “Center” metering, which puts more importance on getting the center of the frame right, while not totally ignoring the corners. The latter was good for mantas passing above me, as I progressively tilted up the camera, meaning my water background was getting brighter and brighter, and I didn’t want this to result in underexposing the manta. If I had had a snoot for the Hybrid Flash, I would have used “Center” more often, or even “Spot.”

Whatever the metering mode, you can apply an adjustment to the camera’s TTL instructions, with the flash compensation setting. I found this quite useful during dusk dives, where I wanted low-key photographs, but the camera tried to compensate for overall darkness. I set my flash compensation anywhere from –2.0EV and –1.3EV during those dives (compared to –0.3EV in other conditions). For macro subjects (less than 18 inches away), Backscatter recommends flicking the mode dial from “SC” to “SC Macro” to avoid overexposing close-up subjects. While this worked well, I preferred dialing down the flash compensation in the camera menus, as this was more convenient.

Switching to Manual

As already mentioned, many animals and underwater scenes can be photographed beautifully in TTL mode, which is great news for beginners. Yet, you will routinely find subject matter that requires adjusting each strobe’s individual brightness, if you are to avoid overexposing parts of the image. This is why I encourage all my students to practice controlling their strobes manually (full guidance provided in The Underwater Club’s Lighting course), to make sure they’re prepared for all photographic opportunities.

For example, if parts of the subject or scene are closer to one strobe than they are to the other, the closer strobe should not fire as bright. While you can try and pull that strobe further away if there is sufficient space around you (the Lighting course also covers strobe positioning to avoid hotspots), I recommend dialing each Hybrid Flash back to “M” (Manual) mode and adjust their individual power dials. You’ll also have to switch the camera from TTL to Manual mode; otherwise, the strobes won’t fire. On the Sony A1, this requires changing the “Wireless Flash” setting from OFF to ON. (Recall that this can be set as a shortcut on the camera.)

I also like to go manual to fine-tune my lighting for very close-focus wide-angle photography. With the strobes so close to the subject, the slightest distance change can result in over- or underexposing parts of the frame, and I prefer using a dial to fine-tune exactly how bright each strobe is.

Having the flexibility to switch between TTL and manual strobe control during a dive is the best of both worlds. This requires three actions—changing a setting in the camera, and rotating a dial on each strobe—but this is reasonably easy to do, without taking your eyes away from the subject.

High Speed Synchronisation

The Backscatter TTL trigger’s High Speed Sync (HSS) compatibility means that the Hybrid Flash seamlessly switches to HSS when in SC mode. If I found myself increasing the shutter speed beyond the Sony A1’s maximum sync speed (1/400s), the strobes would keep exposing my foregrounds, as opposed to being unresponsive.

This instant access to HSS while shooting TTL was a nice surprise, as it isn’t available in Manual mode—you need to rotate the mode dial all the way to the “HSS” position.

It is worth noting that the flash lighting will decrease as you increase the shutter speed, so HSS won’t help you overcome ambient light with flash light. However, this seamless switch to HSS can save a photo from overexposure should you realize that your background is too bright and quickly need to increase your shutter speed past the maximum sync speed.

Burst Shooting

According to Backscatter, the Hybrid Flash can keep up with 3fps continuous shooting in SC or SC Macro mode, and this was consistent with my experience—as long as the camera wasn’t trying to fire the strobe at its highest power levels. That makes sense, since the strobe’s recycle time when firing at maximum power is rated at 2.17 seconds.

When shooting in manual mode, the TTL trigger is capable of sustaining 30fps. I tested this underwater and confirmed the strobes fired consistently—although I didn’t have on hand a subject worthy of that sort of speed. In summary, the TTL protocol with its pre-flashes and review by the metering system is bound to slow things down, but 3fps is usable for most subjects. If you find yourself needing high-speed bursts, that’s another scenario where you’ll switch to manual—and the TTL trigger will oblige.

Trigger Battery Life

Backscatter rates their TTL trigger for 13 hours of continuous use, after a full charge. The longest I have used the trigger between charges was two days in a row, amounting to eight dives in Raja Ampat’s abundant waters, resulting in 1,200 to 1,600 shots taken. This averages to 150–200 images per hour of diving, which really is a lot! (I always shoot more when testing equipment, plus there was no shortage of subject matter in Raja Ampat.)
After eight such dives, the TTL trigger battery indicator would blink once, telling me I had between 20% and 39% of battery left, which sounded consistent with the claim of 13 hours of continuous use. However, I have also had single three-hour-long dives (500–600 shots taken), after which the indicator LED gave only two blinks (40 to 59% of battery left), which left me perplexed.
To understand what was happening, I set the Sony A1 to fire once every three seconds for as long as the camera’s battery would last, in TTL mode (Hybrid Flash set to SC), and I found 4,600 photos were taken before the A1 battery gave up. The TTL trigger still showed “2 blinks” of battery life (40–59% remaining) and the Hybrid Flash was still indicating green (over 50% charge left).
In conclusion, I believe the TTL trigger’s battery indicator is a little conservative, but either way, I found the TTL trigger fired multiple thousands of times before needing a charge. To play safe, I chose to charge it every eight dives—the same time as I was swapping camera batteries anyways. It usually took less than an hour to charge.
It should be noted that the TTL trigger goes into “sleep” mode to save battery life when the camera itself sleeps—or is turned off. I purposely left the trigger in sleep mode for four days in a row (power switch ON) and noticed it had no visible effect on battery life (over 80% charge remained). That is to say, the TTL trigger’s battery won’t deplete itself overnight even if you forget to switch off the camera, and I didn’t bother turning the trigger’s power switch to OFF for the rest of the test period.

Strobe Battery Life

As already explained, for each photo taken in TTL mode, the strobe has to fire a number of pre-flashes, and I wondered what impact that might have on the Hybrid Flash’s battery life.

In a nutshell, during Raja Ampat’s busy dives, I would routinely use over 50% of the strobes’ battery (yellow battery status) in two dives, meaning in “only” 300–400 photos. I am writing “only” because the Hybrid Flash’s battery life is humongous, so TTL does appear to take its toll.

One reason could be that the strobes were firing brighter than usual: I often heard the audible “beep” alerting me that the strobe wasn’t able to achieve the camera’s desired exposure level. This happened on scenes that I know the Hybrid Flash would be plenty capable of lighting in manual mode. It is likely that I didn’t pay as much attention to optimizing my strobe-to-subject distance, since I was less conscious of how bright my strobes were firing when in TTL mode.

In any case, in TTL mode, the Hybrid Flash’s battery life still had enough juice for three very busy wide-angle dives—and even more dives when shooting macro.

Final Words

Having a TTL-compatible trigger for the Backscatter Hybrid Flash makes this strobe more accessible to beginners, with perfect exposures easier to achieve on a range of underwater subjects and scenes.

It is an attractive proposition for experienced shooters, too. Shooting TTL allowed me to work quicker than usual, sparing me the time to adjust each strobe’s power dial. As a result, I rarely passed on a photogenic subject, just because of how easy it became to adjust my lighting! I did have to go back to manual strobe control on various subjects, but overall, having the option of accurate TTL made my dives more productive. 

If I were a Sony or OM System/Olympus shooter, I would definitely be buying Backscatter’s TTL trigger to pair with the Hybrid Flash. Let’s hope that Backscatter releases Canon and Nikon versions in the future.

About the author

Nicolas Remy is an Australia-based pro shooter and founder of online underwater photography school and photo club, The Underwater Club, with members in 18 countries. He serves as an ambassador for Nauticam and Mares, and chair of the jury for the DPG Masters photo competition. His work has been widely published in print and digital media, and his images have won over 40 international photo awards. To see more images by Nicolas and his wife Léna, visit their website, www.nicolaslenaremy.com.