8. Jan, 2022

A team of scientists from China has identified an early volcanic winter as an additional force that likely contributed to a mass extinction event 250 million years ago in a period called the end-Permian.

Left: The fossil skull of Dinogorgon rubidgei one of the large predators that disappeared during the end-Permian extinction. Photo Jonathan Blair/Corbis. 

The analysis of minerals in southern China indicates that volcano eruption produced a 'volcanic winter' that drastically lowered earth's temperatures -- a change that added to the environmental effects resulting from other phenomena at the time. The research, which appears in the journal Science Advances, examined the end-Permian mass extinction (EPME), which was the most severe extinction event in the past 500 million years, wiping out 80 to 90 percent of species on land and in the sea.

A plausible scenario Most striking was the drastic simultaneous increase in the concentrations of minerals like mercury and copper, suggesting massive volcanic eruptions (on a much larger scale than the current eruptions). The large amounts of sulfuric acid atmospheric aerosols produced a rapid global cooling, followed by a harsh volcanic winter worldwide. Hereafter, the temperature quickly rose again, causing enormous quantities of CO2 to be pumped into the atmosphere, resulting in massive global warming. An additional factor could have been the strong greenhouse gas methane that was released from the melting permafrost, or from the warmed seabed (like we witness in present days). Oceanic acidification may have been another contributing factor. The overall results were devastating, such that forests disappeared to make way for huge bare plains and large predators such as dinos died massively at the end-Permian. This whole process probably took place over hundreds of thousands of years,  contrasting with modern industry-related global warming that started only some hundreds of years ago, in which volcanic activity plays only a minor role. 

15. Jun, 2021


China employs between 7 and 9 million fishermen (over 14 million industry-wide) who operate over 450.000 fishing vessels   (of which nearly 200,000 are ocean-going vessels) comprising the largest fleet on Earth.

Paramilitary power of the South-China Sea (SCS) China claims about 90% of the vast  SCS, an area made up of hundreds of small islands, atolls and coral reefs (see the red line in the picture et the left)*. It has even built new habitats  at an emergency rate, with 3000 m. runways for aircrafts on  several of the Spratly_Islands  at  the western side of the Philippines and NW Borneo**. This involved also   artificial islands created by dredging sand onto coral reefs which were then concreted to make permanent structures. This project, dubbed Great Wall of Sand, refers to an area where  naval ships can anchor, and bunkers have been built for the storage of ammunition, missile silos and radar systems. Overflying aircraft are sharply warned to avoid the airspace in these areas. These examples indicate that  China wants to bring the SCS under full Chinese control. However, the Spratly Islands are also claimed by Taiwan, Vietnam, Malaysia and the Philippines, contesting China's claim to almost all of the Sea for decades, and  arguing that that  Chinese ships are violating their maritime rights. Five years ago the Permanent Cour of Arbitration in the Hague has established that these waters indeed fell within the customary exclusive economic zones of those countries.  It also rejected Chinese claims of sovereign right on these waters on historical grounds and that it has been  using large fishing boats to enforce ownership of islands and atolls.  

The cause of the SCS disputes: there aren’t enough fish in the sea. One of the explanations for China's recent assertiveness in the SCS is its struggle to supply the insatiable need for Proteins (fish) of the motherland, using huge numbers of fishing vessels, in areas far beyond China's territorial waters. The catch along the  Chinese coast has diminished  drastically.  But also in the waters of the SCS an estimated 70 to 95 % of the fish species disappeared, bringing the region’s fisheries in serious jeopardy. According to recent estimations, virtually all fishery stocks in the  SCS are collapsed (roughly 25 percent), over-exploited (roughly 25 percent), or fully-exploited (roughly 50 percent). The situation is only worsening, as manifested  in March, when  200 Chinese large fishing boats anchored on the Whitsun reef near the Philippines, presumably not manned by fishermen but by civilians under the authority of the Chinese army's coastguard. These expansions on the sea have also fuelled fears  in Western countries that the flexibility of China as a creditor of infrastructure projects in  East Africa, such as the Belt and Road Initiative, are in fact economic expansions meant for profit. 

*Source (a.o.)  NRC 4 Juni 2021. Buitenland 12 (G. van Pinxteren article)

**The Spratly  islands may sound familiar to those who had the opportunity to visit  Layang-Layang  atol (also called Swallow Reef) a  remote  superb Malaysian diving location in the SCS, which can be reached by a 1 h flight with a small airplane from Kota Kinabalu in NW Boneo.


4. Feb, 2021

Inon has released the D-200 as a successor for their D-2000 strobe, which is actually a simplified version of their Z-330 with a smaller guide number and without a separate electrical cable connection. The strobe's acrylic dome helps to spread the beam of light, which covers a full 110 degrees. The exposed dome of the strobe can be protected from bumps and scratches by keeping the diffuser on permanently.

Picture taken with Olympus M1 II in PT-EP14 housing without a port-dome. Olympus Zuiko 8mm fisheye, and internal flash trigger.  ISO 200, F9, 1/50.  The strobes can be triggered by  using the external flash, as well as the new AOI STR-04 LED trigger. 

Compared with my former strobes, the Ikelites DS 161 (see my Blog of May 17),  the major advantage of the D-200's is their smaller size and weight. The underwater weight of the D-200 is 4g/0.14oz negative including the Strobe Light Shade and 4 x AA  Enelope batteries. The light output (guide number 20) was largely sufficient for some close-focus-wide-angle test shots that I tried on our window sill (see insert above).  D-200 strobes with standard diffusers were set at a lower intensity (manual -4) setting, and placed close to the housing, pulled backward at the same level as the camera. I could not yet determine the merits of the rotatable shade caps of the strobes.  I think they can be a handy device once you have worked out your specific lighting and flare problems underwater. The only problem is that you have to decide before the dive about taking off the caps because it would be difficult to take them off during the dive.   In the low -180 deg- position (used in the test picture),  the cap can be useful to prevent reflections from a sandy bottom close to the camera.  In the horizontal (90/270 deg) positions they may prevent backscatter, but also create a shadow in the center of the frame. When placed at the side near the housing they may prevent accidentally seeing the reflection glare of the strobes in your images when using a fish-eye lens and shooting  CFWA.   The strobes can be triggered by using two optical cables, by either the camera internal flash or LEDs.  One can also decide to use only one optical cable for the first strobe, and let the second strobe perform as a 'slave' to the first strobe with an adapter screwed on its sensor.  The acceptable risk is that other photographers in your vicinity may also trigger your slave flash and an inconvenient time. 

Selection of settings  Settings on the rear panel to control the advanced circuitry of the strobe are pretty complex. The focusing light is controlled by a button at the lower left. The most simple flash setting described above is manual control with 13  steps of adjustment of the intensities of the flash (see the short article describing the Z330 which has the same control buttons on the rear panel as the D-200). The power selector has stops at both minimum (-0.5) and maximum (-6) power settings. Notice that variations in the intensity of the flash are achieved by very small changes in the duration of the flash signal on a msec scale. A second option is S-TTL, a technique that enables the strobe to perform in an optically slave-controlled TTL mode.  In this case, you first need to release a button on the rear panel (lower right) to select pre-flash. Pressing the shutter-release button will then let the camera's built-in  flashlight trigger the pre-flash signal via the control circuitry in the strobe,  emitting a pre-flash to the UW object.  The camera then  'sees' this pre-flash, judges the subject to be close to the camera, and decreases the power (duration) of the main flash by the camera, triggered by the built-in flash. According to the INON manual, the two requirements for using the fast S-TTL option of the D-200 strobe is a camera with a built-in pop-up or accessory flash to transmit light to an optical fiber, and the camera set to  TTL or fill-in flash. Although I never use TTL,  it remains interesting to follow the efforts designers of UW strobes and cameras make in further developing these techniques. 



20. Aug, 2020

 Some positive and negative perspectives of the recent viral crisis are summarized below:

-The famous diving locations in the world have practically been deserted during the lockdown of the past months. Backpacker  Ian Melvin from the UK who found himself stranded on the Galapagos Islands when the coronavirus lockdown came into force declared  “No one will get the opportunity to experience the Galapagos so quiet. ‘The swimming here’s amazing, the sea lions come right up to your face. Marine iguanas swim next to you and penguins peck your feet'  (see inset). In the Mediterranean,  National park rangers have observed greater biodiversity as manifested in an increase of groups of dolphins, floating groups of puffins, gannets, tuna hunting and gray heron passing by.

-The lockdown down also had positive effects on wildlife in National Parcs in Africa and the US. What about the creatures that live under the waterline?  In Cape Town South Africa the lifting of shark nets paired with drumlines for the duration of the lockdown allow the sharks to move a little more freely.   The bad news is that the long line fishing of hundreds of sharks a day is being allowed off Cape shores during the lockdown, even though the industry provides relatively few jobs, harms marine biodiversity, and offers no food security. White shark expert and naturalist Chris Fallows says: “It is a disgrace that a fishery which is, according to scientific evidence, unsustainably killing already collapsed shark stocks, is allowed to continue. When this is done under the banner of an essential service it becomes a tragedy."

-Some have speculated that underwater creatures that enjoyed many visitors in the past may become restless and even distressed by their absence. Like, for example,  in the Sealife aquarium in Blackpool where the staff is keeping their stingrays, sharks, and fish calm during the coronavirus lockdown by playing music and singing to them. Perhaps the same might happen at the famous shark baiting sites in the Bahamas where Emma, Patches, and other top sharkish predators are starting to miss their regular bait providers and visitors? Finally, the most significant spin-off of the lockdown seems that the number of unprovoked shark attacks at some notorious beaches in the  USA has sunk to dramatic lows, likely a side effect of closed beaches and widespread quarantines.

-Divers that feel fully recovered after being infected by the Coronavirus could still suffer lung damage which could permanently prohibit scuba diving and other forms of exercise.  In this respect, the disease is like viral pneumonia, which would also require a long period of convalescence before returning to diving.

-Recent updates suggest a continuation of safety regulations, local lockdowns and hazards connected with traveling in overcrowded planes to diving destinations, probably extending to the year 2021. This holds for areas in the Caribbean, Indian Ocean as well as the Red Sea. Visitors of the Bahamas will need to submit a  negative COVID PCR test result in the period 10 days before their visit.  A the end of July The Bahamas counted 1610 confirmed  COVID cases and 23 deaths (on a population of around 400.000).  Moreover, all visitors and returning residents are also required to quarantine for fourteen (14) days upon arrival into the Bahamas.  From 1 September, all persons (including those who hold Egyptian nationality) arriving from overseas, to any part of Egypt, will be required to present a negative PCR test certificate on arrival. The Egyptian authorities have advised that PCR tests must be conducted no more than 72 hours prior to arrival in Egypt.

-Padi has recently published an interactive map, presenting the latest information from each PADI dive center to provide the most up-to-date status right from the source. It shows that diving is still possible in most countries around the Mediterranean and the Red Sea. This however does not preclude that health officials maintain strict health regulations for tourists entering these countries, such as a  negative PCR test and a quarantine period. This may also hold for dive-centers  and liveaboards in the Red Sea.

-Conclusion: COVID-19 travel restrictions and border closings are constantly evolving. Nonessential travel is banned between some destinations, and others mandate a two-week quarantine period for travelers at the start or end of a trip, However, In the current maze of safety regulations,  the best strategy for the eager UW photographers is to exploit the photographic possibilities in their own country.  Hopefully,  the current collapse of the diving industry and the resulting frustrations of grounded Scuba divers will not last forever, and their former favorite tropical locations will become accessible again, as soon as the virus,  or at least its most dangerous symptoms are under control. An  example a useful initiative to help travelers to cope with Covid hazards in foreign countries  is Travel safe of Tripadvisors. It is meant to filter out health and safety regulations of their  travel destinations (mostly hotels and resorts). I would be nice if organizers of Scuba diving trips could follow the same procedure for their specific destinations, hotels and liveaboards

October 2020: See for a recent update of travel restrictions: travel advisories

17. May, 2020

 Left: my current choice of lenses and domes for the PT-EP 14  and PT-EP10 housings,  each accepting the same lenses and domes.  Upper left:  OMD PT-EP14  with Olympus 8mm fisheye and a 4-inch dome, Upper-right:  PT-EP14 with Panasonic 7-14 zoom with the AOI DLP 08 dome.  Lower left:  Panasonic 7-14 zoom with Zen WA-100-EP714 dome and Olympus 8mm with the 4-inch Precision dome plus extension. Both domes need the OMD-PEN adapter when placed on the PT-EP14 housing. Lower right, the new AOI UH EPL-10 housing with  INON D-200 strobes, on an Ikelite tray. The E-PL9 camera replaces the older E-PL5  in the PT-EP10 housing.  The  UH-EPL-10 housing will take the AOI port and kit 14-42 lens, as well as the Oly 8mm  (with extension) and the Pana 7-14 mm zoom lens.  

In the ever-growing market of UW photo equipment, it becomes increasingly difficult for the beginning UW photographer to choose the right underwater system.  New technologies also bring better ergonomics,  lenses, and more megapixels which easily will make the older system look awkward and obsolete.  There are limiting factors that will make the choice easier.  Like your budget of course. And the more experienced photographer often has developed a specific interest, like shooting macro or wide-angle subjects.  Or choosing a cropped sensor instead of a full-frame sensor which will automatically limit the spectrum of lenses and housings. Then there is also the type of strobe to select, and the system to fire the strobes, electrical cables of fiber optics, in which case there is a choice between either an internal flash or LED trigger to ignite the optical system.   For strobes and lenses, the underwater market seems to change less rapidly. The choice of the lens is crucial for the quality of your pictures, perhaps much more important than the number of megapixels of the camera, or even the size of the sensor.  A superb lens will stay with you for many years, at least when the housings designers are so kind as to provide the suitable adapter and port for your favorite top lens

From  DSLR to 4/3  format For about 20 years I  have been a faithful user of the Ikelite DSLR housings  and Nikon DX cameras equipped with the legendary  Tokina 10-17  with  a Precision 5 inch  mini dome, allowing to get very close to the UW object. But recently I followed the urge to try something (a bit) different and more simple and switched to the PT-EP14 housing with the newer Olympus M1 Mark II camera inside. But I kept my  Oly fish-eye and 4-inch dome (that I used on  my PT-EP10 with E-PL5 back-up system) which so far seems to work well on the OMD housing with a PEN/OMD adapter.  Another change was that from the bulky Ikelite DS 161 to the smaller  and lighter INON D200 strobes 

Olympus AOI upgrades The Hong  King form AOI has recently brought two new housings on the market for Olympus  4/3 camera's that is:  the AOI UH-EM5III-CAM  for the new Olympus OM-D E-M5 Mark III and the AOI UH-EPL10 which is meant for the EPL9/EPL10 Olympus cameras and replaces the older PEN (PT-EP10) housings. Both polycarbonate housings have added two important options, namely a vacuum system and a LED system, avoiding the energy-consuming internal flash.  I am now using the AOI UH-EPL10  housing with EPL9 camera (see insert lower-right) as a backup system.  This housing offers two pleasant extensions, namely a vacuum test system, and a multi-control LED trigger system (that so far seem to work flawlessly), making the pop-up flash of the older  PT-EP10 PEN housing superfluous. A new AOI STR-04  LED trigger is now also available for the OLY PT-EP14 housings, although the older flash will also do very well with the M1 Mark II, with the flash set to lower  (1/64) power to not drain the batteries.  The picture above shows my current choice of lenses and domes for the PT-EP 14 housing.