DivePhotoGuide tested the TRT-Electronics e-Turtle Smart 3 TTL flash trigger with a Canon R5 II. Key takeaways before you invest.
It's a small device that is placed between the camera housing and the port, and it transmits the flash exposure information to the external strobe, enabling automatic TTL (Through-The-Lens) metering instead of a fixed manual setting.
DivePhotoGuide tested the trigger with a Canon EOS R5 Mark II, paired with a Backscatter Hybrid Flash (HF-1) and a Retra Flash Pro Max II, two high-end strobes on the market.
Nicolas Remy, for DivePhotoGuide, published on July 28, 2026. The manufacturer TRT-Electronics provided the equipment that was tested.
Not always. A recent TTL trigger primarily offers benefits in terms of high-speed synchronization (HSS) and the reliability of exposure measurements when shooting moving subjects. If your current trigger already meets these needs, then upgrading is not a priority.
A flash trigger is the kind of accessory that we never talk about until it stops working, and then we curse every flaw the moment it fails during a dive focused on wildlife. DivePhotoGuide has just published its review of the TRT-Electronics e-Turtle Smart 3 TTL, and the testing methodology used is worth noting.
The journalist, Nicolas Remy, tested this trigger with a Canon EOS R5 Mark II, paired with two high-end strobes: a Backscatter Hybrid Flash (HF-1) and a Retra Flash Pro Max II. This choice of equipment is significant. Testing a trigger with high-performance strobes more easily reveals its limitations than a test with entry-level equipment, where synchronization issues often go unnoticed.
TRT-Electronics provided the equipment for this test, a common and transparent practice in specialized underwater publications, provided that the connection is disclosed, which is the case here.
I often say in my training sessions: a flash trigger and TTL mode never replace an understanding of light. A good system makes execution easier once you know what you're trying to achieve, but it doesn't make decisions for the photographer. This is a point I elaborate on in my article on when flash truly enhances underwater images, and it remains true regardless of the trigger used.
For a photographer who already has a reliable trigger, this type of test is primarily useful for objective comparison before a future purchase, rather than creating a sense of urgency to replace equipment that is still working very well.
The AquaExposure training covers the logic of flash exposure, TTL, and manual modes, even before discussing equipment. AquaExposure training.
