Triggerfish remote strobe sensor

Continuing on with remote strobe testing.

Triggerfish is a wonderful little slave trigger made by Hedwig Dieraert. Here's a review on Wetpixel

To test how sensitive it is underwater I toddled off to St Leonards for a dip.

Vis was maybe 6m and Triggerfish worked perfectly 10m away where I couldn't even see the strobe anymore.

Just need to design some method of positioning the sensor like a spike, clamp or mini tripod.

Bounce flash underwater

I don't hesitate to use bounced flash when photographing above water but it had never considered it underwater.

On a recent dive on the ex HMAS Canberra frigate, in less than perfect vis, I tried a few shots with the strobe pointing up at the ceiling of the wheelhouse. The results were a great improvement over direct flash which produced bad backscatter.

Top image is direct flash, single strobe.
Lower image is the bounced flash version.

Sync cord end clip

Here's a little refinement after the initial test dive.

This clip allows the raw end of the sync cord to be fitted and removed underwater. This will allow much easier rolling out of the long cord now that the little hooked clip is not permanently attached.

The clip is stuck to the strobe by double sided tape.

I have also made up a short optical sync cord for use with a slaved on-camera strobe. This means I can just use a single electrical sync cord for the main strobe instead of the annoying double electrical cord.

Remote strobe underwater

So here's my first attempt.

The sync cord worked flawlessly, but it's so awkward dealing with 10m of coiled cable attached to strobe and camera.
It gets hooked and tangled on everything, not as bad as a reel and line but still frustrating.

Conditions were not great with 5m vis green cruddy water and heaps of dive classes in the vicinity.

Fibre optic sync cord from audio cable

Fibre optic sync cords are a great option for underwater strobes but they are expensive and delicate. A 0.5m coiled sync cord costs around A$70. Digital audio cable, which is basically the same thing, costs maybe A$2.00 a meter.

Here's how I adapted a 10m toslink audio cable ($20 on ebay) to work with my Inon strobes. I'm intending to use the long sync cord to setup some remote strobe lighting in sites like wrecks, under ledges and behind pier piles.

First to make the slave strobe end I cut through one of the Toslink plugs leaving a lip which would sit inside an Inon sensor cover.

I carefully shaped the lip diameter and depth to hold the cable in the sensor cover and allow the sensor cover to be screwed over the sensor.

To make sure the cable didn't pull out of the lip I used plumber's PVC pipe glue.

That seemed to work very well but I also used heat shrink tube and cable ties to secure it even more.

The sensor cover can still rotate freely.








Finally to fit the master strobe end of the sync cord.
I cut the plug off leaving a raw end and made a PVC bracket to hold it in front of the master strobe.

The bracket fits around the sensor and the PVC material is thin enough, about 1mm, to allow the sensor cover to screw down securely, holding the bracket in place.






Here's the whole setup, now all I need is some decent vis!

Inon strobe on Gorillapod

Here's how I mounted the strobe onto the tripod.

A piece of aluminium flat was shaped to fit the gorillapod mount with a cutout slot to accommodate the locking lug.

The strobe and gorillapod combination is negatively buoyant but I added a 0.3kg ankle weight for a bit more stability.

Off-camera underwater strobe

I have started mucking around with a remotely triggered strobe underwater.

The aim of this is to create more interesting lighting. Using an off camera strobe to add rim lighting or even back lighting can add depth and drama to an image.

The tricky bit is actually getting the remote flash to fire. Water absorbs light much more than air so the in-built Inon slave sensor is only effective over about 1.5m. Any further back and the main strobe will not trigger the remote strobe, at least in our murky sub-temperate water. 

There are a couple of solutions.

1. Use a really long sync cord, either fibre optic or electrical.

2. Use a more sensitive electronic remote sensor. These are available for Ikelite strobes but not my Inons, although one should be available very soon. 

I have ordered 10m of fibre optic audio cable to try a long sync cord. One end will sit in front of my main strobe and the other will connect to the remote strobe. This means the cable will be visible in the shot of course.

Stay tuned for new developments.

Strobe arm floats

The housing and strobes are still quite heavy underwater especially with one strobe positioned for rim or back lighting.

To add a little buoyancy I cut 80mm sections off a pool noodle ($3.99 from Rebel Sports) and slipped them over the strobe arms. This made the rig much easier to handle underwater. The foam does compress a bit with depth but works beautifully for shallow dives. Could be improved with even longer foam sections.

This photo also shows the white velcro strips used to hold the sync cords to the strobe arms and the green lanyard and clip for hanging the rig from my shoulder d-ring.

The flags in the map behind mark Portsea Hole, Portsea Pier and Blairgowrie Marina.

Inon sync socket replacement

In a previous post I mentioned that one of my Inons needed a replacement sync socket.

The problem probably originated 4 yrs ago when I bought one of the first Ikelite to Inon sync cords. The finish on the Inon end of the cord was awful with razor sharp edges and vice crimp marks. I brought this to Ike's attention and they replaced it no questions.

However the damage had already been done. The few times I used the original cord had scratched the o-ring sealing surface of the Inon. I smoothed and polished the scratches fairly well but I guess over the years enough salt water seeped through to cause corrosion of the contact pins.

This came to a head in Tassie when I didn't undo the sync cord for maybe 36 hrs and the photo shows the result.

Anyway I sent it off to Sea Optics for a replacement. Total cost was $330 including $135 for the socket, $127 labour plus o-ring kit and pressure test. Way more than I expected but this ain't a cheap hobby! Strangely the socket was installed 180 degress rotated to where it was, meaning the brass locating pin was at the bottom.

It worked well for the 10 or so dives since but then the socket started to rotate when screwing and unscrewing the black plastic locking collar on the sync cord. Apparently the socket must have sustained a knock or I have tightened it up too much (neither of which I am aware of) wrenching the locking pin out of it's hole behind the socket.

The strobe is now holidaying again in Adelaide and I shudder to think what the bill will be.

So that's why I haven't posted many images lately.