Underwater Strobes

Let’s start with a simple fact: you can’t take photos without light. I know, this isn’t a huge surprise for most people. But this has a lot of implication for underwater macro photography. What light you have is usually weak and it’s a funny blue-green color. There are just a handful of ways to counter this: shallow dives with an adjusted white balance, a handheld dive torch, a camera-mounted wide-angle video light (or several), and strobes.

My Inventory

I own 3 different strobes.

Sea and Sea YS-01. This is a small strobe with not a lot of power. I own only one of these and have for quite awhile. It’s great for underwater macro with a compact like my trusty TG-5 and TG-4. Its size is good to add on to my camera setup without adding much weight or bulk, and as my blog readers will know, small components are the name of the game when I take the compact on a dive. However, the strength of these isn’t so good for wide-angle.

Sea and Sea DS-02. These are my usual strobes for diving with my Lumix G9. They have medium-strong power. I’ve had to replace a couple of them over time because of corrosion in the battery compartment. They work awesome for macro if I use a dome diffuser and put then right up along the sides of the lens. These work well for wide-angle if you use two of them and you’re 2 meters or so away from the subject.

Scubalamp P53 Pro. These are my new video lights with a strobe capability. I added these earlier this year. They’ve been a bit of a trial to use just as strobes, but they are great video lights. They are heavy and need some flotation in water which isn’t much of a problem with a wide-angle setup and a huge glass dome but they’re very negatively buoyant on a macro rig.

Diffusers

Diffusers are a mixed bag of results, so you need to give some thought on when to use them. They’re a piece of plastic that fits on the front of the strobe. The idea is that they bounce the light as it goes through them.

So instead of having all the light come from one direction, it’s like having a bunch of mini strobes in many directions. This reduces the dark shadows and bright highlights in a photo that’s not quite as dramatic. This also had a side-effect of reducing some of the backscatter in your photos.

Diffusers also increase the angle that is illuminated by the strobe. I think it’s easier to shoot with diffusers since you don’t have to be as precise with where you aim the strobe.

However, diffusers have one downside: they reduce the total amount of light reaching the subject. This is around 1-2 camera stops which is a small limitation in how you shoot.

Diffusers come in flat or round shapes. The round shapes bounce the light in even more directions.

I have a set of Carbon Arm round diffusers for my DS-02 and I use them for macro. I don’t user a diffuser with the YS-01 although I’ve tempted to buy a dome diffuser for it. The P53Pro comes with a flat disk diffuser that fits under the front ring and I use those.

Signaling Strobes

There are 2 ways to signal strobes to fire: fibre optics and electronic cables.

I haven’t used electronic cables because they require that you have a hole, called a bulkhead, in the housing to put the electrical connection.

All of my shooting is done with fibre optics. They’re just a long piece of fiberglass with a plastic coating and some standard plugs. When light shines on one end, it shines out the other end.

For cameras that have a built-in flash–TG4/5/6 and my older EM10MKII– housings have holes right in front of the camera flash to hold the fibre optics.

For cameras that don’t have a built-in flash, you use a miniature LED flash, called a flash trigger, that fits into the camera’s hot shoe.

The strobes themselves have a plug for the fibre optic and a sensor that can tell when light comes through the fibre optic.

Strobe Layout

Single Strobe

For macro, you can easily use one strobe. You can experiment with distance from the camera body and light angle. This is a pretty easy setup to shoot with.

For cameras with a port, place the strobe on a medium-length (10-20cm) arm in the center of the housing so that it reached out over the end of the lens port. Point the strobe down.

For compact cameras, you can mount the strobe directly on the housing or on a small (5-15cm) arm for a little bit more flexibility.

Twin Strobes

I put my strobes up against the port at 9-o-clock and 3-0-clock and facing inwards a bit, maybe 20°. The diffusers are about even with the end of the port. This is more about getting the arms to work than the strobe and I don’t put too much thought into it unless I have extreme amounts of backscatter or I’m doing some weird style of shooting.

If I need to fit into a smaller area, I’ll move them up to 10-o-clock and 2-o-clock like Mickey Mouse ears. That lets me slide the lens front into smaller areas sometimes.

If I’m shooting a long-distance macro shot like little fish (blennies being a huge favorite), I’ll move the strobes out away from the lens port maybe 15-20cm. That limits the backscatter.

Free-Range Strobes

I know several photographers that mount strobes on small weighted tripods so that they can place them anywhere they want. They either keep the strobe connected via fibre optic or they have a fibre optic cable that plugs into the strobe and has an exposed fiberglass end that will catch the light from their on-camera strobe.

Troubleshooting

I’ve had days where I was not happy with my strobes. There are many things that can go wrong, and when they do go wrong, you shoot black photos. I have a lot of these on my network storage drive. I’ve seen my wife lay her camera down on the sandy bottom and swim away from it and I’ve felt like that myself.

Is the Strobe Flashing?

Hold a hand in front of the strobe to reduce noise from other lights and take a test shot. You should see the strobe fire into your hand. This is part of my pre-dive camera setup routine. If the strobe doesn’t fire, then the rest of the troubleshooting tests apply.

If the strobe fires but your photos are still black, then it’s one of 5 things:

Camera is set to use TTL but strobe is not. Easy fix is to set the stove to TTL mode and see if that exposes the photo properly. Harder fix is to check the camera settings to turn off TTL. TG4/5/6 calls this “RC” (remote control). Lumix calls this “Flash Mode”. Also one warning here: I don’t know of any flash triggers for Micro Four Thirds that do optical TTL.

Camera is set to “second curtain”. This is where the flash fires at the end of the exposure. In some cases this will mean that the strobe fires too late. Try first curtain and see if that works.

Shutter speed is too fast to “flash sync”. Set shutter speed to something like 1/125. Most strobes can’t sync faster than 1/250.

Camera exposure is too dark. Bump up the ISO to 400, appetite to F8, and shutter speed to 1/125.

Lens cap is on. We’ve all done it before.

Is the Camera Flashing?

If the strobe doesn’t fire, the first thing to check is if the camera is making a flash. Most of the time you can do this by removing a fibre optic cable and watching the now-empty hole while you take a test shot.

If the camera won’t flash, then there are several reasons why.

Camera is set to “quiet mode”. This turns off the shutter noise and the flash. Great for wildlife photography, bad for underwater macro.

Flash trigger is not turned on, doesn’t have batteries, or isn’t seated properly in the hot shoe.

Flash is set to “automatic”. Setting it to “fill-in” forces the flash to fire regardless of how bright the photo exposure is.

Is the Fibre Optic Broken?

This is very common, they don’t like much abuse. Check the connectors for obvious damage. Pull the plug off of the stove, fire a test shot, and see if you get a flash coming it of the cable.

Always carry extra fibre optic cables. Swap them out and see if that fixes the problem.

New Batteries?

Strobes seem to get schizophrenic when their batteries are low. My DS-02 need the flash power turned down when the batteries are half used, otherwise they don’t fire at all. Changing batteries fixes this.

The Backup

I always have a focus light of some kind on my camera and I try to carry a cheap video dive torch when I dive. In instances where I am having troubles with my strobes and I can’t figure it out after a couple of minutes, I’ll switch to using torches and keep the dive going. Things like that are usually better to sort out on the surface. Best to keep calm and carry on with taking shots.

See you underwater!!!

–Mike

Screwing with my Dive Flag

I now live in Massachusetts. Like many states in the US, divers are required to carry a dive flag. Mine is on a stick connected to a big yellow lobster buoy. There is a simple hand spool attached to it. Yay boats can see me, but is also hard to give away one hand to hold a spool while you shoot tiny things on the bottom of the ocean.

After a couple of incidents where I had to surface and chase my dive flag because it tried to run away, I stopped in to my local dive shop (Undersea Divers in Danvers) and asked if they had any advice. The answer that I got was to use a dog leash screw. They use them with open water students to “anchor” the dive flag and practice ascending and descending along a line. Pretty cool and cheap solution for me.

These look like a giant corkscrew and they are used by screwing into the ground and then attaching your dog’s long leash to it. It keeps your dog from running away, it should also keep your dive flag from running away. The one thing is that they’re obviously not made of stainless steel so they do rust out over time.

The “albatross” I have to carry on every dive. There is a different type that is a big round insert tube with a storage space in the middle.

Giant corkscrew with a bolt-snap connected via zip-tie. Also works if you meet up with a huge bottle of wine in the middle of your dive.

Pet supplies store packaging. Well-grounded!

For pet use only. Why do I have images in my head involving staking out your children at the park?

See you underwater!!!

–Mike