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albert kok

Member Since 02 Sep 2006
Offline Last Active Yesterday, 01:16 AM

Topics I've Started

Using a mini-altimeter as a leak detector

07 May 2015 - 10:04 AM

Commercial  leak-detectors are based on the principle  that a barometric underpressure (or: partial vacuüm) that is sucked in your housing with a hand pump, rises above a critical  level. In that case a red LED on the detector starts blinking: probably a leak!  If you  already have a vacuüm pump, but no detector, a  mini  altimeter (basically a small barometer translating mbars in feets of altitude) can  be very helpful. At least if you a have a transparent  Ikelite housing. I use this little and  cheap  device ALTIMER ONE that I stick  to the inside of the  Ikelite housing. After  the vacuüm is established  (around 20 strokes) you read out the pressure in feets altitude (say 4000 fts). Giving you an objective indication of the pressure inside your housing. So you want to be sure that this reading doesnt change, say in the next couple of hours.


I haven't  yet checked  the altimeter reading  during a dive. Its possible that the air pressure  inside the housing may drop a bit, because of the decrease of water temperature (and  cooler air inside the housing) with increasing depth. This will give  you a higher reading on the altimeter. No reason to panic. Only a sudden lower reading on the altimeter means trouble. Apparently water is entering the housing, which  causes  a rise of  the inside pressure  Have fun!.

Wanted: Nauticam Optical 0.66x Viewfinder

03 May 2015 - 01:16 AM

Send me an Email: albertkok69@gmail.com if you have this   finder for sale


What can WIFI do for the UW Photographer?

20 April 2015 - 09:13 AM

Some new SLR camera's have built in WIFI, combined with NFC (Near Field Communication). I tried it out with  the Nikon D7200 connected with a Nexus (Android) tablet. It seems to work fine on land. You can trigger your camera with your tablet  via remote control, and look at the screen of your tablet for the result. Also, you can inspect the content of your SD card  and then dowload it to your tablet. That could be an advantage  when the camera is still in your housing and you dont want to remove the card. But then you would still depend on a WIFI network. That  may not always be available on your diving trip, like on a live aboard.Can anyone think of a useful application of this WIFI option?

Blue sharks attacked and eaten by fur seals

11 April 2015 - 04:27 AM

Chris Fallows observed and photographed Cape fur seals (Arctocephalus pusillus) attacking and partially consuming  free swimming  mid-sized blue sharks off Cape Point, South Africa. One seal was even seen to attack five sharks in succession within two hours. The seals were mainly interested in the nutritious parts like stomach content and liver of the sharks. See also the recent article by Chris a.o.



The behavior of  these fur seals reminds me of grey seals (Halichoerus grypus) that are now hold responsible  for attacking and consuming porpoises in the coastal waters of the Netherlands. Jeremy Stafford just sent me this link confirming the unusual (or hitherto unkown) behavior of grey seals attacking and partially consuming Harbour porpoises off the coast of  west Wales.



Great hammerheads of Bimini

18 January 2015 - 06:19 AM

Athough the  Bahamas lack the splendid colourful reefs of the Indian Ocean and the Red Sea, they do have one big promise for the UW photographer: an abundance of big sharks. Moreover, thanks to responsible baiting of sharks it is possible to  encounter in the Bahamas almost any type of shark on a specific location. This means that the chances of actually meeting a bull, tiger or even the miraculous great hammerhead on your trip have become better and better in recent years.

Last week I had the opportunity to visit the great hammerhead on Bimini.  A shark that I had missed on my earlier trips to Tiger Beach, which is not so far from Bimini. The organiser Neil Watson Jr. and his team take very well care of the sharks as well as their visitors. Apart from some variation in the weather, diving conditions were excellent.

I'm  therefore glad to post here a link to some recent pictures of the GHH from last weeks visit.