Strobes not firing underwater

Hi everyone,

I am brand new at using my Nikon D850 with Isotta housing and Sea and Sea YS-D3 strobes (manual, with optic cable). I have however been diving for over a year with same strobes and a Sony RX100 V camera, so not completely new to UW photography, nor new to DSLRs which I have been using on land for over 10 years.

The issue I have is that my strobes did not fire underwater. I dive in dark, low viz waters of South California. I tested the strobes on land before the dive (daylight) and they worked well. Underwater, not at all, despite my multiple attempts I made through the dive (night dive). After coming home from the dive, I tried the strobes again in the garage and they still did not fire. I checked if the camera sends the trigger for the strobes (red light through the optical cable holes) and it does. Next morning, I woke up and tried the strobes again in the garage, and they worked. This seems so puzzling and wondering if anyone can offer thoughts on this.

During the dive I had a Sola 1200 mounted on top of the camera. I honestly don't remember if I had it at full blast of 1200 lm or a lower setting. I could only think that this light was not enough to trigger the strobes in the dark water, just like it was not enough in the garage artificial light after the dive.

Thanks so much.

YS-D3s are known to be hard to trigger optically. With a D850, I assume you're using an LED trigger, right? It's probably putting out just enough light to trip their sensors, and when water gets into the connectors, it absorbs a little bit of light and that puts you under the threshold.

Are you using single-core or multi-core cables? If it's the former, the better light transmission of multi-core cables should be able to resolve your issue.

Barmaglot_07 wrote:

YS-D3s are known to be hard to trigger optically. With a D850, I assume you're using an LED trigger, right? It's probably putting out just enough light to trip their sensors, and when water gets into the connectors, it absorbs a little bit of light and that puts you under the threshold.

I've heard the same.  For whatever reason, the D3's trigger harder than earlier versions.

I've got 4 YS-D1's, one of which has a dead flash bulb.  All triggered fine with my Nauticam NA-D850 using the standard (non-TTL) flash triggers.

I'm suspecting that the triggers are right on the edge of having enough power to trigger the stobes, and perhaps even replacing the batteries will help.  There are TTL triggers available as another possible solution.

Are you using single-core or multi-core cables? If it's the former, the better light transmission of multi-core cables should be able to resolve your issue.

My rig is using fiber cables I ordered in 2016 for my NA-D810 housing, which used the pop-up flash as a trigger.  Never knew there were different fiber types out there.

PHXAZCRAIG wrote:

There are TTL triggers available as another possible solution.

TTL, by itself, will not do anything to alleviate the issue. What's needed is raw power. If you look at Sea & Sea's own triggers that work with YS-D3s, they use twin AAA batteries, and chew through them pretty damn quick, as they use very bright LEDs. For comparison, UW-Technics triggers last for months on a coin cell battery.

My rig is using fiber cables I ordered in 2016 for my NA-D810 housing, which used the pop-up flash as a trigger. Never knew there were different fiber types out there.

Pop-up flashes are more forgiving, as they put out a much brighter pulse. The cheaper cables use a single fiber optic core, but better light transmission is achieved by using a bundle of thinner fibers - typically 613 of them. This is what it looks like under a microscope:

As I understand it, the thin individual fibers reduce light transmission losses from cable bends, as the same bend radius is proportionally greater for a thinner fiber. With my old strobes (SeaFrogs ST-100 Pro) I had an issue where one strobe would fire reliably and the other wouldn't, as it wasn't getting as much light from the camera flash due to the way the reflector inside the housing is constructed; swapping to multi-core cables made that problem go away.

I managed to get through 31 dives with the original 2-year-old 2032 coin batteries in the NA-D850 housing.  On the other hand, the 2032 in the vacuum leak detector had to be changed out shortly into the trip.   Only about 50 previous dives on the housing, all in 2019.

SilvyG wrote:

Yes I am using a LED trigger, and I can see the red light flashing from the camera ports (on land). I did not check if there is red light flashing while diving, evidently by pulling out the optical cables.
I am using Sea&Sea individual optical cables. Can you please elaborate a little on what multi-core cables are?
Thanks for your help!

Example: http://www.divervision.com/howshot-fiber-optic-cable-613l-for-seaandsea-ys-strobes-OFL613-SS.html

They use a bundle of 613 thin fibers instead of a single thick optical fiber - this reduces light transmission losses from cable bends.

SilvyG wrote:

Do you think that switching from optical cable to electronic can fix the problem? I would have preferred to stay with optical cables due to lower maintenance but some $6,000 later, I need a system that works. Getting the electronic cable and the Nikonos bulkhead is another $315 but considerably cheaper than buying 2 other strobes.
I asked Isotta about their housing compatibility with YS-D3, hopefully they will answer at one point. A bit slow service from Italy.
Thanks so much!

I think you're missing the obvious - replace the LED trigger with a stronger one, not the strobes.   Cost around $400, I think.  The i-Turtle Smart TTL trigger advertises compatibility with the YS-D3.

SilvyG wrote:

I would like to circle back with the current situation. I got the strobes to fire underwater this weekend, on two dives. I have changed three things:
- mode of shooting for the strobes. Backscatter advice was to use the second mode which is without pre-flash. It worked on land but very sporadically in the water. The mode that worked consistently in the water was the first mode (with pre-flash)

That seems very surprising to me.   What trigger comes in the Isotta housing?

I've always used the 2nd position with my YS-D1's and Nauticam D850 trigger, but the YS-D3's have that color-coded.   Are you using the orange or green setting?

What flash settings do you have set on the camera?

PHXAZCRAIG wrote:

SilvyG wrote:

I would like to circle back with the current situation. I got the strobes to fire underwater this weekend, on two dives. I have changed three things:
- mode of shooting for the strobes. Backscatter advice was to use the second mode which is without pre-flash. It worked on land but very sporadically in the water. The mode that worked consistently in the water was the first mode (with pre-flash)

That seems very surprising to me. What trigger comes in the Isotta housing?

I've always used the 2nd position with my YS-D1's and Nauticam D850 trigger, but the YS-D3's have that color-coded. Are you using the orange or green setting?

What flash settings do you have set on the camera?

The manual optical trigger is made by Isotta, and I had it installed at the time I ordered the housing. I am using the first position (orange), which is with camera pre-flash. I was told to use the green but when that didn't work consistently, I tried the orange. I have done now 4 dives with it and it worked well every time.

For the flash settings, I followed the advice from Backscatter and reset it to the factory settings. So whatever they are...happy to look if you tell me which setting you would like to see from the Menu.

Thanks.

It sounds like the Isotta trigger is a TTL trigger if it uses preflash.

Which of these triggers did you get, the manual one or the TTL one?

https://www.backscatter.com/brand/Isotta/department/Lighting/product-category/Flash-Triggers

I think you have a TTL flash trigger, and to do TTL it must use preflash.

Now you just need to see how to run it in manual mode when you want to.   Eventually you'll find situations where TTL doesn't do what you want.    When I was shooting TTL (pop-up flash on D810), I had more issues with overexposure and highlight loss than I do using manual flash exposure.    I found that out when forced to do manual flash with my D850 Nauticam trigger.

Looking closely at the photos listed for the TTL/non-TTL triggers, I'm pretty sure they used the same image for both products.

SKU is different, as it price.  I suppose you could test it above water.