“So what’s your favorite dive site?” asked a freshly scuba addicted student yesterday. “Ummm… That’s a really hard question!” I’d replied. He looked puzzled, “Why?” Why indeed. I am a PADI Instructor, as are many of you. I am sure … Continue reading →
The post My Top 3 EMEA Dives – Part 1: Million Hope Wreck (Guest blog by Alexandra Dimitriou-Engeler) appeared first on PADIProsEurope.
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Archaeologists excavating the famous ancient Greek shipwreck that yielded the Antikythera mechanism have recovered more than 50 items including a bronze armrest (possibly part of a throne), remains of a bone flute, fine glassware, luxury ceramics, a pawn from an ancient board game, and several elements of the ship itself.
“This shipwreck is far from exhausted,” reports project co-Director Dr. Brendan Foley, a marine archaeologist with the Woods Hole Oceanographic Institution (WHOI). “Every single dive on it delivers fabulous finds, and reveals how the ‘1 percent’ lived in the time of Caesar.”
The shipwreck dates to circa 65 B.C., and was discovered by Greek sponge fishermen in 1900 off the southwestern Aegean island of Antikythera. They salvaged 36 marble statues of mythological heroes and gods; a life-sized bronze statue of an athlete; pieces of several more bronze sculptures; scores of luxury items; and skeletal remains of crew and passengers. The wreck also relinquished fragments of the world’s first computer: the Antikythera Mechanism, a geared mechanical device that encoded the movements of the planets and stars and predicted eclipses.
The 2015 expedition is part of a long-term research program at the site, which began in 2014. It was the first scientific excavation of the wreck, and launched the first comprehensive study of all of its artifacts. During the new multi-year program the team expects to recover artifacts and ancient artwork still buried in the seafloor, and recreate the history of the ship’s exquisite cargo and its final voyage.
An expedition mounted in 2014 the researchers created a high-resolution, 3D map of the site using stereo cameras mounted on an autonomous underwater vehicle (AUV). Hampered by bad weather, the expedition included just four dive days for professional technical divers who recovered a series of finds on the surface sediment and proved that much of the ship’s cargo is indeed still preserved beneath the sediment.
By contrast, this year’s expedition included 40 hours of bottom time, with four professional archaeologists diving the site and performing controlled excavation to the highest scientific standard with specially designed equipment, and with the guidance of an exquisitely precise multi-dimensional map of 10,500 square meters of sea floor.
In addition to Foley, the 2015 exploration at Antikythera was conducted by the Greek Ephorate of Underwater Antiquities under director Dr. Ageliki Simosi and field archaeologists Dr. Theotokis Theodoulou and Dr. Dimitris Kourkoumelis.
The international team was in the field from 26 August to 16 September, following an autonomous robotic mapping effort conducted from 8-15 June in partnership with the University of Sydney, Australia. The project is the first-ever systematic excavation of this shipwreck, relying on the precise large-area map created by the robotic survey. Notably, this project marked the first time in the century since the wreck’s discovery that archaeologists were able to join specialist divers in descending to the 55-meter (180 feet) deep site. The ten-man dive team used advanced technical diving equipment including closed-circuit rebreathers and trimix breathing gases, performing 61 dives in 10 days of diving on the wreck. A remotely operated vehicle (ROV) monitored and recorded all diving activities, and served as a communications link between divers and support personnel on the surface.
The 2015 expedition has left the team with the best understanding yet of this unique shipwreck and its cargo. A metal detection survey of the site revealed that metallic targets are dispersed over an area of about 40×50 meters. This is thought to match the wreck’s debris field, indicating the vast size of the ship that sank off the forbidding cliffs of Antikythera.
Metal detectors revealed the presence of buried objects throughout the wreck site. The dive team recovered items including an intact amphora; a large lead salvage ring; two lead anchor stocks (possibly indicating the ship’s bow); fragments of lead hull sheathing; a small and finely formed lagynos (or table jug); and a chiseled rectangular stone object (possibly the base of a statuette) perforated by 12 holes and filled with an as-yet-unidentified substance.
During the project, the dive team carefully excavated a series of nine trenches in the seabed using a water dredge powered by a submersible pump. The divers recovered more than 50 artifacts, most deeply buried beneath a thick layer of coarse sand and massive deposits of broken ceramics. From among these fragments, the team recovered wooden remains from the hull of the ship; a section of bronze furniture, perhaps from a throne; part of a bone flute; a glass “chessman” board game element; bronze nails from the ship’s planks; and portions of bronze, iron, glass and ceramic objects.
“We were very lucky this year, as we excavated many finds within their context, which gave us the opportunity to take full advantage of all the archaeological information they could provide,” states diving archaeologist Dr. Theodoulou.
The team created 3D virtual reconstructions of many artifacts on the seafloor, and 3D-modeled all of the major recovered artifacts once on shore. A series of scientific analyses are now being conducted on these artifacts, including ancient DNA analysis of ceramic jars to identify the 2,000 year-old food, drinks, perfumes, and medicines contained in them. Isotopic analysis of lead objects will determine where the lead was mined, to reveal the home port of the ship.
Previously recovered artifacts from the Antikythera Shipwreck will be displayed in a special exhibition “Der Versunkene Schatz das Schiffswrack von Antikythera” [The Sunken Treasure of the Antikythera Shipwreck] at the Basel Antiquities Museum in Switzerland from 27 September 2015 to 27 March 2016. This is the first time that these ancient treasures have been allowed to leave the National Archaeological Museum in Athens.
The 2015 project team includes Greek and foreign archaeologists, technical divers, engineers, photographers, filmmakers, technicians, etc. (Y. Bitsakis, D. Conlin, J. Fardoulis, N. Giannoulakis, C. Kaiser, Μ. Kelaides, E. Kovacs, C. Lees, D. Manoliadis, Ε. O’Brien, O. Pizarro, D. Romios, B. Seymour, P. Short, G. Smith, Α. Sotiriou, A. Tourtas, Μ. Tsimperopoulos, S. Williams). The robotic mapping surveys were conducted by the Australian Centre for Field Robotics of the University of Sydney. The research team expressed gratitude to supporters of their project including the Swiss premier horology company Hublot S.A., the Swordspoint Foundation (USA), the Aikaterini Laskaridis Foundation, Jane and James Orr, private sponsors of the Woods Hole Oceanographic Institution, Costa Navarino, the Municipality of Kythera and the community and residents of Antikythera, and OTE-Cosmote, which provided telecommunications in the field.
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit www.whoi.edu.
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Marine Archaeologists Excavate Greek Antikythera Shipwreck Read More »
Your PADI empowers you with confidence to be a better diver and a better person. It lets you learn more about yourself and what you are capable of achieving. Your PADI is your passport to adventure. It lets you access the ocean planet and swim with the magical marine life […]
Casting Call: What Does ‘My PADI’ Mean to You? Read More »
On the 19th and 20th September 2015, the first ever PADI Instructor Examination was conducted in Gozo. With candidates from Bubbles Dive Centre (Gozo) and Reefers and Wreckers (UK), it proved a great success with a 100% pass rate! Congratulations … Continue reading →
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First PADI Instructor Examination in Gozo has 100% Pass Rate! Read More »
If you’re not already shooting with the help of your camera’s histogram, it’s time to start. A histogram is a graph that shows the distribution of tonal values from black to white in your image, and it’s a very accurate indicator of overall exposure. If you’re not checking out the histogram as you shoot, your exposures are a guess at best.
ALL DATA ARE NOT COLLECTED EQUALLY
ETTR (exposing to the right) is a RAW-image-capture technique that increases the exposure of an image in order to maximize the amount of data collected by the camera’s sensor.
Because the digital image sensors collect 50 percent of all available data in the single brightest stop, underexposing your photo by even a small amount is tantamount to tossing a significant amount of information out the window. An underexposed shot often looks just dandy on the back of the camera, but in fact, the LCD preview is a terrible predictor of exposure. Use the histogram to analyze what kind of exposure you’re capturing with each shot.
For the sake of this example, let’s say that a camera has five stops of dynamic range (from darkest to brightest) and shoots a 12-bit RAW image, which is capable of recording a total of 4,096 tonal values. You’d think that each of the five stops should be able to record 850 tones — about a fifth of the total — but that’s not how it works. In reality, the brightest stop (farthest to the right on the histogram) collects a weighty 2,048 values, with each subsequent stop to the left (darker) recording half the amount of the previous one. In short, the right side of the histogram holds the data, and the left side holds the noise.
WHEN TO USE ETTR
This technique isn’t something you’ll necessarily use on every shot. It’s not easy to use the ETTR technique when the dynamic range of the camera is already pushed to its limits; for instance, when shooting sun balls or other ultra-high-contrast scenes. ETTR pays of most in moderate- and low- contrast shooting scenarios, where the ultimate goal is to bias your exposure brighter, with the histogram snugged up to the right, but not so far to the right that the highlights get “clipped” by running into the right edge.
DON’T OVERDO IT!
Pay close attention to the camera’s highlight-warning “blinkies.” When you see them start to flash, it’s time to back off. They’re a friendly reminder that you may be in danger of blowing out highlights. Specular highlights, which are reflections of light from shiny surfaces like water, fish scales and critter eyeballs, might not contain enough critical detail to worry about in small amounts, but completely obliterated highlights are not recoverable and spell doom for your picture. A little clipping is OK; a lot is bad.
BASIC POST WORK FLOW FOR ETTR RAW CAPTURES
All ETTR images need work in post. Right out of the camera, ETTR captures often appear washed out or overexposed. All those yummy tones in the brightest part of the image need to be mashed back toward the left of the histogram in order to restore richness, saturation and contrast to the shot.
Remember, the Highlights and Shadows sliders are detail sliders meant to restore detail in bright or dark areas without affecting clipping. The Whites and Blacks sliders establish the actual white and black points in your photo.
In the Basic panel, slide the Highlights slider all the way left.
Slide Exposure toward the left to lower the overall brightness level.
Add Contrast if necessary.
While holding down OPT (Mac) or ALT (PC), click on the handle of the Whites slider. You’ll see a black- clipping preview screen. Slide the handle toward the right until you begin to see small areas of color. Slide back toward the left until just the tiniest pinpoint of light pixels remains. Those light pixels are the white point in your image.
Slide the Shadows slider to the left until the shadow details are as you desire.
While holding down OPT (Mac) or ALT (PC), click on the handle of the Blacks slider. You’ll see a white- clipping preview screen. Slide the handle toward the left until you begin to see small areas of color, then slide back toward the right until just a smidge of dark remains. Those dark pixels represent the black point in your image.
Re-adjust any of the Basic panel sliders as needed.
Move on to the HSL panel (Hue, Saturation and Luminance) and local tools.
Click here for more photo tips, or head to scubadiving.com/photos
Imaging: Understanding Your Camera’s Histogram Read More »
