Sunday, June 29, 2014

Do I Really, Really Need a Strobe?

By Bill Van Antwerp
One of the more common questions we get asked, particularly from newer underwater photographers is “I am going to shoot some photos and some video; do I really need a strobe and a focus/video light or can I get buy with just a light?”

To answer the question I set up some tests both in the studio and while diving from the Conception at San Miguel Island (Channel Islands, CA). In the studio setup shown below, I set up a “mandarin fish” in a bed of rocks. The fish is about 2 inches long. For the test in the studio and in the water, I was shooting an Olympus OMD-EM5 in a Nauticam NA-EM5 housing with 2 Sea and Sea YS-D1 strobes using the 12-50 Olympus lens in the Nauticam focus port. For continuous lighting, I used either one or two Light and Motion Sola 1200s, iTorch Pro 6s or Nocturnal Lights M700i.

Figure 1 –Setup in Studio
In the fashion and portrait studio world, LED lighting is becoming wildly popular because with studio LED panels both the color temperature and the brightness can be adjusted on the fly. Underwater we have no such luxury and none of the three lights that we tested had continuously variable intensity levels, but rather two (Nocturnal) or three (iTorch and L&M) levels of brightness.

Figure 1: The setup at left shows two strobes and a single focus light; for the case of two lights the lights were placed where the strobe are shown.

Figure 2 – 1/250th, f/22, ISO 200, 2 YS-D1 Strobes.

Figure 2:
For a baseline, I shot my mandarin fish at 1/250th of a second and f/22 at the native ISO of the camera, 200. The photo above shows the results of this shot with both YS-D1 strobes set at 0 power. A flash meter reading suggested F/18 for this shot and notice the background is a bit dark but overall this is well exposed and notice that the depth of field is quite large.

One advantage of shooting with strobes is that you can have exquisite control of the depth of field by manipulation of the aperture. Below is a shot of the fish at 1/250th and f/6.3 (the minimum of this lens). The strobes were shot at minimum power for the strobe on the left and 1 notch above minimum power for the strobe on the right allowing for adjustment of the darkness of the shadow on the left rear of the photo.

Saturday, June 14, 2014

Sea of Cortez: The Only Sure Thing is Whale Sharks!

Twenty-one underwater photographers boarded the Solmar V dive boat in Cabo San Lucas, Mexico, on June 23rd expecting to steam the next 25 hours to the Revigadagos Islands, aka "The Socorros", 250 miles offshore. Alas, "Amanda" had other ideas.

Having built up to a Category 4 Hurricane, Amanda was an early violent storm a few hundred miles south of Socorro Island and heading straight for the area we were to dive. Needless to say, the Captain told me that we had to make a big change and head north into the Sea of Cortez. I had taken several trips to the Sea of Cortez ten years ago, but I hadn't enjoyed the long runs to the dive sites from shore. This would be a great opportunity to re-explore it from the comfort of a large live-aboard.

The good news was that the diving there is pretty good, and we could be diving the next morning in Cabo Pulmo.

After a checkout dive, we dropped on the wreck of an old tuna boat, descending right through 9 large bull sharks. Enjoying large schools of grunts and snappers. We explored what was left of the old boat, really just a few large pieces, seeing the large sharks circling in and out amongst our group in somewhat murky conditions.
Continuing north towards La Paz, we dove La Reina and Swanee Rock, both teaming with life. Diving in the Sea of Cortez is very "fishy" with huge schools of grunts, snappers, goatfish and others on nearly every site. Friendly pandemic green morays also greet you from almost every hole. Corals are mostly hard, and not all that colorful, so the aquatic fish life is what you go for. Yellowtail sturgeon fish, puffer fish of every variety, colorful hawk fish, and grouper abound on nearly every site.

However, with a boat load of photographers bent on looking for large animals, we decided to take some chances. Whale Sharks are found in La Paz bay in the Spring; but there had been no reports so far. Would we spend a half-day to cruise the bay and most likely find nothing? A multi-cultural debate raged that evening over dinner, as the French contingent felt the whale sharks weren’t guaranteed, but were finally out voted.

Tuesday, June 10, 2014

Lenses for Underwater Photography

Buying the best lenses - and ports to use them in, can be a long-term value investment. Lenses and ports can be used over and over as you buy new cameras. Buying high-quality lens solutions as you can afford them is the best plan. However, planning what lenses to buy and what format to invest in is a very important decision.

Most cameras come bundled with an inexpensive “kit” lens. These vary in value underwater, but generally aren’t wide enough, focus close enough, or offer the best sharpness to be used well underwater. The extra expense of extensions, gears and ports can make these “inexpensive” lenses poor investments in the long run. Many new underwater photographers end up selling them after a short while after being disappointed with the results.

Underwater we generally want three general focal length ranges of lenses; all with the idea of getting as close to our subject as we can. Water absorbs light, color and clarity; eliminating as much of it as we can gives us the best results.

Those ranges are ultra-wide (usually fish-eye), mid-range zoom, and macro. Ultra-wide fisheye lenses yield the best corner sharpness, due to the loss of one-third of our field of view underwater, they become rectilinear. Their “round” corners match the dome ports that replace much of this loss of field of view. Normal wide-angle rectilinear lenses, as great as they are above water, generally don’t focus as close, not have the corner sharpness we desire, due to refraction.

For more information about what lenses we recommend please see our Guide article in our Educatiion section of the store site.