• Scuba Skills Tune-Up
• It's Easy...
• Diving in Dominca
• Photography Part 4 - Lighting
• The History of Scuba Diving - Part 1
• What in Crininy is a Crinoid
• Coral Bleaching
• ADA Dive-Cruise Update
• What Should I Take On An International Dive Trip?
• Diving Tips & Tricks: Clearing Ears
• Diving Attitude Part 1 - Pitch Axis
• Buddies From Hell
• Easter Island Statues Come to Deerfield
• ADA T-Shirts For Sale
• Have You Moved or Changed Email Addresses Lately?
• Newsletter Delivery
• ADA Guidelines and Policies

Events and Activities: Ongoing Scuba Tune-Up Clinics taught by Safety Officers and PADI-certified scuba instructors. Clinic topics include re-familiarization and assembly of scuba equipment, proper use of equipment, and refresh on the typical pool skills with scuba equipment taught in the Open Water course. Also covered will be safety topics, equipment, dive planning, underwater environment, computer use, etc. Note: This is not the official PADI scuba refresher course and participants do not receive any sort of certification for this event. Discover Scuba Diving is for non-divers to experience diving for the first time in the pool, limited to 8 participants.

Lunch: Poolside lunch served after the pool session compliments of ADA.

Equipment: Participants must bring their own scuba gear – mask, fins, snorkel, BC, regulator and weights. Each participant must also bring one filled air tank. Many local shops will rent the necessary equipment.

Volunteers Needed: If you would like to volunteer for the registration table, lunch setup, clean-up, or clinic instruction, please contact Rachel at rachelhancock7@gmail.com or call 786-316-9852.

Spread the Word and Bring Your Friends! We want to use this event to get in as many new members as possible so please spread the word and bring your friends. There will not be another opportunity to join ADA for just $25 for the rest of the year.

To RSVP or More Info: Contact Rachel Davis at rachelhancock7@gmail.com or call 786-316-9852.

There are dozens of dive sites near the south end of Dominica from easy to difficult, depending on the current. Dangleben's Pinnacles are easy to moderate, while the dives on the other side of Scott's Head Pinnacle can be demanding. Diving is not all there is to do in Dominica. After a morning of clear water diving, an leisurely hike to one of Dominica's many waterfalls and pools easily fills the afternoon. Hikes to Titou Gorge (where you can swim or float through the caverns), Emerald Pool, and Trafalgar Falls all have non-taxing access trails. Try a more demanding hike on an non-diving day. Boiling Lake is a 6 hour round-trip to a volcano-heated lake of boiling water. A guide is recommended on this hike.

If hiking is not your forte, Dive Dominica has fabulous shore diving right off their dock. Grab a tank and jump in. Octopus, sea horses, corals, sponges, schools of fish, and anemones, along with anchors and miscellaneous boat parts are found in less than 25 feet of water. There is a long cable that extends underwater from the dock that you can use for finding your way back to shore.

So, if you are into diving and hiking, the mountainous island of Dominica is worth it, even including the narrow canyon landing on an airstrip that ends at the water's edge! Flights from San Juan, Puerto Rico are readily available as well as from other Caribbean islands. Many cruise ships also have one day stops in Dominica and have shore excursions to Champagne or other nearby dive sites. Caribbean diving at its best!

Summary - Desirable Features in a Strobe:

• Large Guide Number
• Master/Slave Capability
• Fast Cycle Time
• Variable Beam Angle
• TTL Compatibility
• Small Size and Low Weight
• Daylight Color Temperature

Guide Number: Light output in strobes can be measured in several ways including lux, lumens, and watt-seconds. The most popular measurement and one that can be used across all strobes is the guide number. The guide number, abbreviated as GN, is defined as the light needed to produce a correctly exposed photograph at a subject-to-strobe distance of one meter multiplied by the recommended f-stop (see Photography Part 2 – The Mechanics in the March Newsletter) at ISO 100 with the strobe operating at full power. What’s all that mean? Say for example, the GN of your strobe is 20. To get the aperture setting, divide the GN by the distance. If your subject is 3 meters away (about 10 feet), then you need an f-stop of 20/3 or 6.67 (round down to the next available f-stop, f-5.6). A camera with a built-in flash may have a GN 20 or 30, while a strobe’s GN may be 250 or more. In the case of strobes, bigger is always better, albeit at a price. A strobe can cost as little as $100, all the way to $3000 or more, depending on features.

Master/Slave: Strobes come in two flavors, master and slave. A master strobe is electrically attached to the camera’s shutter mechanism and fires when the shutter is tripped. A slave strobe uses flash detection circuitry to trigger the slave when it “sees” the master flash. The ability to use your strobe in either mode allows it to be used as a primary or, if two strobes are needed, as secondary illumination.

Fast Cycle Time: A strobe only delivers its maximum output if it is fully charged. The charge rate depends on the condition of the batteries and the speed of the charging circuitry. Look for a cycle time of under 2 seconds with a fresh (fully charged) set of batteries. As the batteries discharge, the cycle time will increase, meaning you might not be able to take that second shot of the octopus sliding away. Related to cycle time and battery life is the number of shots per full charge. Expect at least 100 shots per fully charged battery pack. Once again, more is better.

Variable Beam Angle: The ideal strobe angle of coverage is dependent on the subject matter. A wide-angle shot will require an angle of coverage of at least 120 degrees. A wider angle requires more power, so you want to be able to narrow the beam angle when a wide shot is not needed to conserve battery life.

TTL Compatibility: If your camera is a TTL (Through-The-Lens) that can intelligently synchronize with your strobe, then TTL Compatibility is a must. Without TTL capability, you would have to shoot in manual mode.

Size and Weight: You’re going to be carrying around a camera, housing, and spare batteries, so the last thing you need is a bulky and heavy strobe. When traveling to international destinations, be mindful of carry-on and checked luggage restrictions.

Color Temperature: Look for a strobe that delivers daylight lighting. That is, color temperatures of 4500K to 5700K. The warmer 4500K (it’s an inverse relationship) delivers better reds in wide angle shots.

A strobe when used properly will make the difference between a bland, average shot, and a vivid, spectacular shot. Without auxiliary lighting, the underwater environment will steal all the color out of your photos. A strobe restores the lost color and detail and makes your photos come alive. If you’re serious about underwater photography, then a strobe is a must!

used military divers breathing through such reeds at shallow depths to install submerged barriers to impede invading ships. Herodotus describes how two Greek divers, probably breathing through short reeds, cut the Persian fleet adrift during the Peloponnesian War in 415 BC. There are many drawings of divers from the Roman Empire wearing leather helmets with long tubes supposedly supplying air from the surface, but such contraptions could not have worked more than a few feet below the surface due to pressure differentials.

The Greek philosopher Aristotle in the fourth century BC wrote about early efforts to spend more time under water with primitive diving bells: “They enable the divers to respire equally well by letting down a cauldron, for this does not fill with water, but retains the air, for it is forced down into the water.” Sponge divers would work near such inverted containers, returning periodically to take a breath or two.

Breathing is not the only challenge under water. Divers also have to be able to see what they are doing. Around 1300 AD divers from Persia were documented as having invented a rudimentary form of goggles, using thin slices of shells from tortoises that were polished until they could be seen through.

During the 1500s, heavily-weighted wooden barrels with open bottoms were lowered onto dive sites to allow divers to come into the air pocket and get a breath while working at depth.

In 1715, an Englishman named John Lethbridge invented a one-man diving barrel with a glass porthole and arm holes with watertight leather sleeves that allowed a single diver to perform work below the surface. Also in 1715, an English inventor named Becker invented the first real diving suit, made of leather with a large, spherical metal helmet that had a window. Becker’s suit had three hoses leading to the surface: two for fresh air being forced downward by men operating bellows and one for exhaled hair.

Everyone has heard of Sir Edmond Halley, the astronomer whose name the famous comet shares. What few people know about Halley, however, is that he spent extended periods of time deep underwater. In volume 29 of the Philosophical Transactions, dated 1714-1716, Halley published the results of his experimentation in new ways to work comfortably underwater, titled suggestively: “The art of living under water”. Halley’s work, in which he improved existing models of diving bells, turned out to be influential for years after its publication, and his techniques were implemented by many undersea laborers. One of those techniques was to replenish the air in the diving bell by repeatedly lowering barrels of air. He also invented a system using a watertight hood and hose that allowed workers to leave the bell and walk around on the bottom. Halley’s improved diving bell could send several men (there is no reference to women divers back in those days) to the bottom for salvage work, where they could spend up to ninety minutes at depths of up to sixty feet.

It was not until the late 1700s that divers could spend significant time under the surface, following the invention by British Engineer John Smeaton of an efficient air pump that could easily replenish the air in the diving bell. Smeaton’s bell and pumping system became the “state of the art” in diving bells for the next century and a half. His bell was made from cast iron; it had the first efficient hand-operated pump to sustain the air supply via a hose; an air reservoir system and non-return valves to keep air from being sucked back up the hoses when the pump stopped.

In the 1820s the first traditional “hard hat” metal diving helmet was invented by John Deane, using modified firefighting equipment. Deane’s system was improved in the 1830s by Augustus Siebe of Germany. The suit connected to the helmet was made of rubberized twill which protected the diver from the elements at depth. That system was so successful that the English Royal Navy starting in 1839 used it in operations and founded the first ever diving school.

In 1864 an improved diving suit was invented by Frenchmen Benoit Rouquayrot and Auguste Denayrouze. Although it was still not completely “self-contained” because it used a hose from the surface pumping air into a closed helmet, the suit was fitted with a reservoir that would allow the diver to detach briefly from the hose for a period of a few minutes. During the late 1800s diving pioneers experimented with using pure oxygen, learned the hazards of decompression sickness, and expanded the uses of diving for many military and commercial purposes. Submarines became a permanent feature of Navy fleets of major world powers, and humanity’s connection with the undersea world was firmly established.

The author acknowledges resources used in this article including Trevor Howard’s book entitled Stars Beneath the Sea, The Pioneers of Diving (Carroll & Graf Publishers 1999), and the website entitled Underwater Exploration Timeline, which can be found at http://seagrant.wisc.edu/madisonjason11/timeline/index_1700.html In the next installment of this series, we learn how divers cut their “umbilical cord” tethering them to the surface and how scuba was born and evolved into the present time. Dive safe!