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Underwater Photography April 12, 2010

Posted by Chris Sullivan in Photography.
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I like taking pictures underwater and on the surface. The little pocket digital camera I use, bought in 2004, has a housing that is now worth more than many excellent new pocket cameras, which is one of the reasons underwater photography can be very costly.

Last week, I received (by mail order, which saved me about $500) a beautiful new Canon EOS 5D Mark II with a 24-105mm zoom lens. I’d love to use it underwater, but I would need.

  1. An underwater housing, $1,500 to about $5,000, depending on the depth, features and manufacturer.
  2. A wide-angle lens, $800-$2,500
  3. A waterproof case, maybe $200.
  4. At least one, but preferably two strobes and all the kit to mount and sync it, $1,000-$2,000
  5. Flood insurance, perhaps $100 year.

So we’re talking another $5,000-$10,000 on top of what I’ve already bought. I really wonder if I could really amortize this over the number of dives remaining in my lifetime where there would be good picture taking opportunities.

Still, it would be a lot of fun to try.

By the way, it’s an amazing camera. I’m enjoying having a  useful viewfinder again, and the image stabilization and ISO range make shooting in all sorts of low light and high contrast conditions a breeze, even when it’s in fully automatic mode.

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Tec 40, First impressions April 8, 2010

Posted by Chris Sullivan in Technical Diving, Training.
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The DSAT Tec Deep course I took a 3 years ago has been split into 3. The course is essentially the same when you put all 3 modules together, except that there are now incremental certifications on the way to the full 50 metre/165 foot, 100% O2, 2 deco bottle certification.

The 3 courses are Tec 40, Tec 45, and Tec 50, referring to the depth limits in metres for each level. My local dive shop just started a Tec 40 course, we me as the certified assistant. Each level consists of 1 confined water dive and 3 open water dives.

Tec 40 retains the 40 metre recreational limit, but allows up to 10 minutes of unaccelerated decompression, and enriched air mixes up to 50%.

Tec 45 goes a little deeper and permits a single deco gas up to 100%, while Tec 50 teaches two gas decompression (something I have found fairly useless in most (but definitely not all) air diving scenarios.

There are a few loose ends and contradictions. The knowledge reviews are in separate handouts which jump back and forth in the manual, which hasn’t changed from the original course. Worse,  there are places where the standards contradict themselves. One that we’ve already run into in Tec 40 says in one place that deco gas carried by students can never exceed 1.4 PP02 at the deepest part of the dive, while another says that if students are carrying mixes that are beyond 1.4 PP02 for decompression to make sure to remind them of the hazard and proper procedures.

Given that the course is supposed to allow for up to 50% Oxygen to add conservatism to decompression (as we are not talking about accelerated decompression), restricting to 1.4 means the dive can’t exceed about 60′, which renders it useless for practical purposes.

Hopefully these issues will get sorted out with time, and the student materials will catch up with the curriculum. Whilst the Tec Deep had the advantage of a cost-effective way to go through what would be 3 courses with any of the other agencies, the new packaging seems popular with many of the students, some of whom find committing to the entire program to be a bit daunting.