Hi everyone,

I'm having a frustrating issue with my underwater lighting setup and hope someone here can explain the technical reason behind it or offer a solution.

My Setup:

• Camera: Sony A7C II

• Trigger: Backscatter Smart Control Trigger for Sony

• Strobes: AOI P1 Strobes (connected via fiber optic cables), Mode set to Sony

Note: This combination was recommended to me by an underwater camera shop, and I also read a forum post online claiming that the Backscatter Sony trigger is compatible with the AOI P1 strobes.

The Issues I'm Experiencing:

1. TTL Mode (Camera: Wireless Flash OFF):

   • The trigger fires and the AOI P1 strobes flash, but the resulting image is completely black.

   • Camera settings: Mechanical Shutter, Shutter Speed 1/125s, Fill-Flash.

   • It seems like the strobe flash timing is completely out of sync with the shutter.

2. Manual Mode (Camera: Wireless Flash ON):

   • The strobes do not fire at all.

   • When looking directly at the trigger output, the LEDs do not emit any optical flash signal upon shutter release.

   • When setting Wireless Flash to ON, the P1 strobes flash, however image is also black

What I’ve already checked & verified:

• Shutter Type: Set to Mechanical Shutter (Silent Shooting is OFF).

• Shutter Speed: Set to 1/125s (well below max sync speed).

• Release without Lens: Set to Enable.

• Hot Shoe Fit: Trigger is fully seated in the Multi-Interface Shoe and tightened.

• Fiber Cables & Strobes: Cables are good; strobes fire normally when manually testing light signals.

• Trigger Battery & Mode: Fully charged

Any help, insights, or workarounds would be greatly appreciated! Thanks in advance!

Kind regards

Fabian

Have you tried manual mode both in camera and on the strobe?

47 minutes ago, RxSub said:

Have you tried manual mode both in camera and on the strobe?

Hi RxSub

Thanks for your help.

Yes, I tried setting both the camera and the strobe to manual mode.

On the camera: Set to Manual exposure mode (1/125, f/8, ISO 100), Mechanical Shutter, and Fill-Flash.

On the AOI P1 strobes: Set the dial to one of the power modes i.e 4)

The issue is:

When Wireless Flash is ON in the Sony camera menu (which is usually required for optical triggers), the Backscatter trigger doesn't emit any optical pulse at all when pressing the shutter button.

When Wireless Flash is OFF, the trigger fires, but in manual mode on the strobe, the image still comes out completely black (out of sync)."

I mean manual mode flash, no fill in-flash. Fill in is TTL.

@faebuk Sounds like you set up everything right. Can you trigger the AOI flashes by triggering the fiber optic sensor? You can use other flashes in test mode aimed at the sensor. Is light getting through the fiber optic cable? Also the quality of the cable can be an issue with some flash units. Is the flash set for pre-flash or looking for a pre-flash that your A7c doesn't do?

Another thing to note, about TTL, is that TTL may not work with this combination of trigger and flash.

Hope this helps.

Craig

@faebuk Email, sales@backscatter.com and one of our sales guys can help you troubleshoot. +1 831-645-1082

Are you sure that flash trigger works with your strobes?

The Backscatter Smart Control Optical TTL Flash Trigger provides super-accurate, automatic flash exposures with Olympus/OM System and Sony cameras using Backscatter strobes. The Olympus/OM System trigger is TTL compatible with the Mini Flash 2, Mini Flash 3, Atom Flash, and Hybrid Flash, while the Sony trigger is TTL compatible with the Mini Flash 3, Atom Flash, and Hybrid Flash. The Backscatter Smart Control Optical TTL Flash Trigger is more than just a TTL trigger, it also can be used for manual triggering, rapid firing over 30 frames per second, and HSS (high speed sync), all built into a self-contained USB-C rechargeable unit.

My suggestion is get a UW Technics TTL if you want to shoot TTL & manual - if you want to shoot just in manual, save some $$ and get an Underwater Light and Magic trigger (I think there is one for sale here in the Marketplace)

Email Backscatter as suggested. All the backscatter website talks about is compatibility with their branded flashes. Just because a strobe is listed as being compatible with Sony TTL, doesn't mean a particular trigger will work, even if it is said to work with Sony TTL. A lot of this TTL stuff is reverse engineered and may not use the exact Sony protocol for communication in TTL.

It should work in manual though, which is wireless flash on in the camera settings and the strobe in manual mode at one of the fractional power settings (not Sony mode) - something like 1/4 power for testing - which is the mode dial set to 6.

The AOI strobe is likely setup to work in TTL on Sony cameras using the AOI trigger in their housings.

In troubleshooting my own set-up with the Sony TTL trigger, you won't see a flash out of the trigger as it's IR from what I was told. I shoot an A7C with Atom and an MF-2 most of the time, and manual works just fine. With the A7C, the lack of mechanical shutter is a limitation on the HSS feature of the trigger.

Hi all

I just went to the store I bought the stuff. We tested with my trigger and his camera and it neither worked. With his trigger it worked on my camera. Now I received a new trigger and everything works perfect.

Thanks for all your help and hints.

Btw regarding compability: I emailed Backscatter, however didn't get an answer yet. However the store owner told be, that he shoots with the exact same combination for a while. Maybe this helps someone.

Kind regards
Fabian