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errbrr

Member Since 14 Sep 2009
Offline Last Active Sep 18 2016 09:25 PM
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Posts I've Made

In Topic: Austrailian diving in Feb and March

18 September 2016 - 08:59 PM

It's a big country. How much travelling do you want to do? Late Feb will be mid summer and the warmest water temps of the year. It's also wet season up in Queensland so the vis might not be the best if you stay close to shore. Sydney diving is meant to be nice. In the same state you could visit South West Rocks (Fish Rock Cave with lots of grey nurse sharks), Jervis Bay (big rocky reef scenery) or go north for Coffs Harbour and the Solitary Islands (starting to get tropical life).


In Topic: Strobes - does this exist?

18 September 2016 - 08:36 PM

I'm lucky - I dive with the world's most disciplined buddies. :-)

 

For reasons of cave conservation though I wouldn't like to consider a cable option. I can't stand scarred cave floors.

You need a bigger tunnel :-) Long cables are better than tripods from a conservation perspective. You could consider laying one along the line during a setup dive and coming back to take the photo later.

 

The options I outlined require some DIY as they're not commercially available. The other option is to throw a lot of money at the problem - a few 10,000 lumen heads would give you enough power for reasonable pictures dependent on cave size and colour.


In Topic: Strobes - does this exist?

13 September 2016 - 05:10 PM

I forgot the other option - really long strobe cables and well disciplined buddies :)


In Topic: Strobes - does this exist?

13 September 2016 - 04:00 PM

 

Do these work better than Triggerfish? I love the Triggerfish, but sometimes I want to shoot further than its effective range. I also don't want to light the area around my camera all the time which is what ends up happening if you use the on-camera strobes to fire the off-camera ones.

 

https://www.facebook...?type=3

 

Liz knows exactly what I'm getting at. :-)

Nope, the RSUs are much worse. The sensitivity/distance is about half that of the triggerfish and if there's too much ambient light they shut down and refuse to trigger anything.

 

I’ve had discussions with my dive buddy the nuclear physicist, and my Dad’s dive buddy, the guy who built the Challenger Deep sub. Both of them said that trying to change wavelengths from visible light to something else was impractical. The ones I looked at were:

Infrared (used by dry cavers a lot) – attenuation distance in water is about 7cm

Ultraviolet – causes eyeball cancer

Soundwaves – too slow, you’d be looking at shutter speeds of 1/15 or less over 80m distance

 

The best option I could see would be to introduce a delay in the system somewhere and still use the light as a trigger. For example, press the shutter but the shutter is delayed by half a second while the onboard strobe fires. The off board strobes are all delayed by half a second after they receive the flash. This would probably require some fine tuning (understatement!). 


In Topic: Strobes - does this exist?

11 September 2016 - 05:16 PM

Hedwig made me a triggerfish with a piezo switch in it - push to trigger the strobe plus it triggers off light flashes as per normal. Very handy! But I think they were a once off product rather than a commercial run. Other things I have tried include SB105s, the old ikelite substrobes which flashed when first turned on, and using a small LED torch pressed against a triggerfish attached to the off camera strobe. The torch is quite tricky to do with one hand but could be improved by using a push button torch and duct taping parts together. The rise time of the LED is enough to mimic a flash when you first turn it on.

 

Doing multiple flashes underwater during a long exposure requires minimal/no ambient light. I found a small back-up torch on the ground pointed backwards was helpful, and even then myself and my buddy swam into the walls a lot. Composition is tricky but I really liked the lighting impact of reduced on camera light. This photo is a particular favourite. No on camera flash and three strobes on the diver triggered manually during as I held the shutter open in bulb mode until I saw his strobes go off.

 

20130329-IMG_7526.jpg

 

I guess the other option is to use a tripod and multiple short exposures, combined later.