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The author would like to thank TRT-Electronics for providing an e-Turtle Smart 3 TTL Flash Trigger for the purposes of this review.
TRT-Electronics has been making flash triggers for underwater use for over 10 years now, and the Hungarian company has now rolled out their third generation triggers—hence the name “Smart 3”—in both manual and TTL flavors, across four camera brands, Canon, Nikon, Sony, and OM System/Panasonic.
Having already reviewed the excellent TRT-Electronics e-Turtle Smart 3 Manual Trigger for Canon mirrorless, in this article I’m focusing on the TTL version, the e-Turtle Smart 3 TTL trigger. In the following sections, I will discuss the key features of the new trigger and look at the improvements over the manual version.
The front of the e-Turtle Smart 3 TTL trigger (left–right) features an LED indicator, a battery test button (white), an on/off switch, and a USB-C connector. A nice added touch: The demo unit came customized with The Underwater Club’s logo!
TTL Support
The headline feature of the new trigger is, of course, its TTL functionality, which works with a variety of different strobes. Just connect the trigger to your computer via the supplied USB-C cable, and use the TRT-Electronics Mac/Windows software to configure it for the specific strobe you intend on using. The software also allows you to enable a stroboscopic mode, which I discuss in a dedicated section below.
At the time of writing, the following strobes are listed as TTL compatible: Inon Z and S series, Retra Flash Pro Max (Mark I and II) and Maxi, Marelux Apollo III V2 and Apollo S, AOI UIS-P1 and UIS-Q1i, and Backscatter HF-1. I tested the trigger with both the Retra Flash Pro Max II and Backscatter HF-1
With the trigger connected and switched on, you get access to the full Speedlite menu on your Canon camera, allowing you to switch between manual and E-TTL mode as well as access the flash exposure compensation function
I tried the e-Turtle Smart 3 TTL in TTL mode with both the Backscatter HF-1 and Retra Flash Pro Max II for wide-angle as well as macro subjects, and the trigger produced pleasing exposures in most situations. Occasionally, there was a need for flash compensation adjustments, for example, adding a –0.7 EV compensation to attenuate the flash output. (In the case of the Retra Flash Pro Max II strobes, I also had the option of individually adjusting each strobes’ output using their power dials.) Keep in mind, it’s important to pick a metering mode that suits the scene you’re photographing; for example, when snooting a centered subject, choose spot metering to ignore the dark corners.
Ultimately, learning how to adjust strobe power manually gives you greater creative control, so it’s an investment that pays off over time. (See The Underwater Club lighting course for guidance.) Still, a flash trigger like the e-Turtle Smart 3 TTL that gives you the option of automatic strobe exposure certainly smooths out the learning curve.
While it’s easy to appreciate the benefits that a TTL-capable trigger brings for novice underwater photographers, shooting TTL is also valuable in situations where the strobe-to-subject distance is changing erratically, or when you’re task-loaded.
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Shooting in TTL mode allowed me to get closer to subjects mostly without having to worry about strobes power adjustments. When I got very close though (less than a foot from the subject), my strobes leaned towards overexposure and I needed to introduce some flash compensation (Canon EOS R5 Mark II, Canon RF 7–14mm f/2.8–3.5L Fisheye, Nauticam housing, TRT-Electronics e-Turtle Smart 3 TTL trigger, dual Retra Flash Pro Max II, f/11, 1/125s, ISO 200)
For most macro shots, I found I got a nicely balanced exposure by using evaluative metering and a slight positive flash compensation (Canon EOS R5 Mark II, Canon RF 100mm f/2.8, Nauticam housing, TRT-Electronics e-Turtle Smart 3 TTL trigger, dual Retra Flash Pro Max II, f/11, 1/25s, ISO 200)
Maximum Sync Speed
First, some seriously good news: With the e-Turtle Smart 3 TTL, my Canon EOS R5 Mark II could sync with strobes at up to 1/320s when enabling “Sync Speed Priority” in the External Speedlite menu. This option is only meant to work with specific Canon Speedlite flashguns, and I didn’t expect it to work with underwater strobes, but it does with the TRT-Electronics TTL trigger. I also discovered that the same is actually true for the manual version of the trigger, which I hadn’t realized while writing my e-Turtle Smart 3 Manual review. Although I didn’t test it personally, I have been told that this sync speed is achievable with the Canon EOS R6 Mark III, too.
Burst Speed
If you care about sync speed (like most underwater photographers working with strobes), you will select “Elect 1st curtain” for shutter mode on your Canon mirrorless camera. In this mode, my EOS R5 Mark II, the camera used for this review, can shoot at up to 12fps.
While some flash triggers slow down the camera’s continuous shooting speed—the camera seems to wait for the trigger and you get fewer images captured per second—that does not happen with the e-Turtle Smart 3 TTL. Impressively, it can sustain 12fps bursts in both manual and TTL modes.
Whether or not TTL bursts are usable in real shooting conditions also comes down to the strobe and the chosen power output. For instance, my Retra Flash Pro Max II strobes were able to keep firing at a lower power level and provide good exposures for six frames, thereafter producing intermittent blackout frames.
A couple of seconds earlier, these two seal pups (captured off Narooma, New South Wales, Australia) were three feet away from my lens; the next moment, they nearly rolled onto my dome! Shooting short bursts in TTL allowed me to get a decent foreground exposure even when the subject distance was unpredictable (Canon EOS R5 Mark II, Canon RF 7–14mm f/2.8–3.5L Fisheye, Nauticam housing, TRT-Electronics e-Turtle Smart 3 TTL trigger, dual Retra Flash Pro Max II, f/11, 1/250s, ISO 400)
Battery Life and Maintenance
Just like the manual version, the e-Turtle Smart 3 TTL has a huge battery life. I’ve been using it for weeks and thousands of shots without having to recharge its battery; based on my dive logs and tests, I estimate the battery life to be well over 10,000 shots (like the manual version of the trigger). In practice, I wouldn’t bother turning off the trigger (there’s a physical switch for that) unless I wasn’t going to dive for weeks. The only two times I charged it, it took less than two hours.
It is easy to recharge the trigger or change your settings by connecting it to a computer via the USB-C interface
Installation
The e-Turtle Smart 3 TTL trigger comes with two optical connectors that attach to your housing’s fiber-optic ports using double-sided tape. Installation was straightforward, and after six weeks of use, neither connector showed any sign of coming loose. The trigger body can be disconnected from the fiber-optic cables if needed, for instance, during charging. However, given how infrequently charging is required, I found it easiest to leave the entire assembly installed permanently in my Nauticam housing, and simply connect a long USB-C cable when a recharge was needed.
Two “rings” of double-sided tape, provided with the e-Turtle Smart 3 TTL, stick on the black discs at the ends of the fiber-optic cables, making it a breeze to hook the trigger up to your housing’s fiber-optic ports
High-Speed Sync
The e-Turtle Smart 3 TTL offers a high-speed sync (HSS) mode that works with compatible strobes like my Retra Flash Pro Max II and Backscatter HF-1 strobes. HSS allows the use of shutter speeds faster than the camera’s normal sync speed, which can be useful when shooting in bright, shallow water or when capturing fast-moving subjects.
Diving mostly in temperate waters, with the trigger syncing at up to 1/320s, I didn’t have much use of HSS while shooting for this review. Still, I tested this feature on land with both the Retra Pro Max II and Backscatter HF-1 strobes and found it worked as expected.
My wife Lena and our kids snorkeling in Narooma, New South Wales, Australia (Canon EOS R5 Mark II, Canon RF 7–14mm f/2.8–3.5L Fisheye, Nauticam housing, TRT-Electronics e-Turtle Smart 3 TTL trigger in HSS mode, dual Retra Flash Pro Max II, f/11, 1/400s, ISO 400)
Second Curtain Sync
Canon mirrorless cameras default to first curtain sync and only allow second curtain sync when a compatible Canon flash is detected. Fortunately, this annoyance is not an issue when using the e-Turtle Smart 3 TTL trigger, which is detected as a Canon flash and lets you access the complete flash function settings menu.
What’s more, the e-Turtle Smart 3 TTL has built-in memory and will remember this setting even if you turn the camera off. This is an enhancement compared to the manual version of the trigger, which reverts to first curtain sync when the camera goes into sleep mode. If you like to keep your camera in second curtain sync mode, this alone might be a reason to pick the higher-end TTL trigger rather than the manual version.
The e-Turtle Smart 3 TTL trigger gives you full access to the Canon Speedlite menu, allowing you to fire your strobes in manual mode or in TTL mode, and toggle between first curtain, second curtain, and HSS modes
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Top: With first curtain sync, motion blur appears ahead of the fish. Bottom: With second curtain sync, motion blur trails behind the subject, producing a far more natural result. (These photos were shot with a Nikon D500 and a different flash trigger but are included here to illustrate the difference between first and second curtain sync)
Stroboscopic Mode
As already mentioned, if you want to use the e-Turtle Smart 3 TTL trigger in TTL mode, the accompanying Mac/Windows software is required to choose the strobe you wish to use. (If you plan on dialling in strobe power manually, you can safely skip this setup.) But you’ll also need the software if you want to utilize another feature: stroboscopic mode.
What this lets you do is fire the strobes multiple times during a single exposure. This opens up lots of creative possibilities and may well inspire photographers who regularly partake in competitions. For example, you can “print” the same fish several times on a single photo without having to resolve to a double exposure, which is forbidden in by some contest rules, whereas here we’re talking a single exposure.
Here’s a single-exposure photo taken using the trigger’s stroboscopic mode set to fire three times, which is why you see this same cuttlefish “printed” three times on the image (Canon EOS R5 Mark II, Canon RF 100mm f/2.8, Nauticam housing, Nauticam MFO-1, TRT-Electronics e-Turtle Smart 3 TTL trigger, Retra Flash Pro Max II, f/16, 2s, ISO 320)
The software allows you to choose how many times the strobe will fire during the exposure (between 2 and 10), and the trigger will then spread those flashes across your exposure duration. One thing to note: This behavior kicks in only if your shutter speed is between 1/10th of a second and 2 seconds, and only in manual mode (not compatible with TTL).
When configuring stroboscopic mode, you get to decide how many times the trigger will fire your strobe(s) during a single exposure
Final Thoughts
The e-Turtle Smart 3 TTL is TRT-Electronics’ most advanced flash trigger for Canon mirrorless users. Retailing for $460 at Backscatter, it’s about 40% more expensive than the manual version. Price aside, which one you should buy depends on your photographic needs.
If you simply need a reliable manual Canon flash trigger with humongous battery life that shoots fast bursts and maximizes your camera’s sync speed, the less-expensive manual version will serve you well. You will also be able to make use of Canon’s Sync Speed Priority mode and push a little beyond your camera’s X-sync speed.
Obviously, the extra cost of the TTL version is worth it if you want to shoot in TTL—whether that’s often or only occasionally. Perhaps equally importantly, you’ll need to invest in the TTL trigger if you plan on using rear curtain sync a lot or getting creative with the stroboscopic mode. For me personally, these added features were enough to justify permanently installing the e-Turtle Smart 3 TTL on my Canon EOS R5 Mark II.
One of the ways topside photographers use stroboscopic flash is to decompose motion, and with the e-Turtle Smart 3 TTL trigger, you can do it underwater, too! (Canon EOS R5 Mark II, Canon RF 100mm f/2.8, Nauticam housing, Nauticam EMWL-1, TRT-Electronics e-Turtle Smart 3 TTL trigger, dual Retra Flash Pro Max II, f/18, 1/5s, ISO 200)
About the Reviewer: Nicolas Remy is an Australia-based pro shooter and founder of online underwater photography school and community, The Underwater Club, with members in 26 countries. He serves as an ambassador for Mares and Nauticam, and chairs the jury of the prestigious DPG Masters photo competition. Nicolas’ images have been widely published in print and digital media, and have won over 40 international photo awards. To see more of Nicolas’ work or browse his upcoming workshops, visit: www.nicolaslenaremy.com.
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