will wireless flash work underwater?

I am contemplating underwater photography with external flash. I wonder if I use the 7D in UW housing would it be possible to use on

camera flash to wirelessly trigger a Canon EX580 as slave flash? Has it been done?

<p>In or out of the water?</p>

<p>The 580 "wireless" flash isn't radio linked, I think it's looking for an IR signal. The IR absorption of clear water is about 10x that of air, so that would reduce range by about a factor of 10, plus you have several windows to pass through. Murky water would reduce the range even more of course. I'm not sure how you're going to waterproof the slave either, but I guess you could put it in some sort of (IR) transparent housing. The slave flash sensor would have to be able to see the 7D flash output too. It's not going to bounce off things very well, so ithe slave might need to be in front of the camera and looking back at the camera.</p>

<p>So I think it could <em>probably</em> be done, but I think off camera underwater flash is normally done using a wired connection. It's likely to be a lot more reliable.</p>

<p>Note this is theory. I've never tried it. I tend to keep my cameras out of the water as much as possible!</p>

<p>There is photography in the pool and then there is photography in the lake/sea. The 7D can trigger other flash visually via 'slave' unit. Apparently the wi-fi has v. poor reception. I almost constructed such unit. It consisted of rather large 6V (square battery type) flashlight....I'd totally gut it out and install relatively small flash unit. You'd have to check the phys dimensions. The flash unit would be directly hooked up to the 'slave trigger'. The flash unit can be turned on by the switch prior to taking a shot. The trigger has to be sticking out via some sort of translucent bubble. If you look hard enough, you should be able to find one from the top of cleaning product, etc. All of this have to have a tight fit and so does the the switch, the front fresnel and the 'slave trigger'....all have to be waterproofed. You can take it to city pool and test the rig....just as much you should test the exposure too. I'd say run everything in manual, preventing the camera to adjust anything. You may have to dunk this set up several times. Unless the cavity is large and it permits sizable light, it just might be a futile exercise. In any case, you'd need to know what amount of light you will be required to have....in order to come up with adequate lens setting, etc. Most likely this would test your patience....urrr, unless you like tinkering.</p>

<p>Example of the 'slave trigger'. This one is rated to pick up light around 30'....likely less underwater.<br>

http://www.bhphotovideo.com/c/product/350653-REG/Norman_810674_Photo_Eye_Optical.html</p>

<p><br />Good luck. Hope all this makes sense.</p>

<p>Les</p>

<p>Leszek probably has your answer -- an optical slave. I'd suggest also that you do this with a cheap flash (Vivitar 285hv, maybe a Yongnuo) sealed into Ziploc freezer bags (double bagged -- one inside another, with the air burped out). FAIW, I've found that Sonia optical slaves have a very long range (maybe 100 ft), but not if there's a lot of ambient light.</p>

<blockquote>

<p>I am contemplating underwater photography</p>

</blockquote>

<p> <br>

I'm guessing you can hire an underwater housing and applicable lens port for your 7D? If not, your contemplation is going to cost from $1500+ for the housing, and $200+ for the relevant lens port. The other problem you'll have, is that all of the housings I have seen, do not have room for the pop-up flash to be used.<br>

The other problem you'll have is that the Canon flashes are designed for use in air, not 30m down in murky water, so dedicated underwater strobes/subject lights are recommended.<br>

And then we have the problem with buoyancy control. Trying to keep your body stable, floating in mid water, while trying to frame, focus and fire a camera.... Oh the joys ;-)</p>

<p>Thanks for the comments and suggestions. I can try using optical slave with my existing G12 set up (infinitely cheaper than trying to get the housing for the 7D).<br>

I have limited success with Canon G12 in UW housing, one of the problem is the on camera flash highlighting all the debris in the water in front of the camera, so I was thinking that off camera flash might do the trick. I posted my photos from the Maldives in my Photonet workspace, you can see what it looks like in relatively shallow water.</p>

 

<p>There's an excellent book that deals with compact cameras and underwater photography, and the pain of detritus...</p>

<p>http://www.amazon.co.uk/Underwater-Photography-Compact-Camera-Users/dp/111834555X/ref=sr_1_1?ie=UTF8&qid=1360677992&sr=8-1</p>

<p>It has a load of examples using Canon cameras and it also shows the settings used.</p>

<p>I can't help you with how well the light signal would travel underwater, but I wanted to pick up on one thing you said:</p>

 

<cite>one of the problem is the on camera flash highlighting all the debris in the water in front of the camera, so I was thinking that off camera flash might do the trick</cite>

 

<p>Don't forget that the trigger is an on-camera flash, so while it isn't providing a lot of light to the scene if you're only using it as a trigger, it's still providing some. It might still highlight the debris a bit.</p>

<blockquote>

<p>Don't forget that the trigger is an on-camera flash, so while it isn't providing a lot of light to the scene if you're only using it as a trigger, it's still providing some. It might still highlight the debris a bit.</p>

</blockquote>

<p>Exactly right! One way around this might be to use a Wein Ultraslave system. It uses a tiny infrared flash and an uber-sensitive slave on the remote flash. Its sensitivity is high enough that it MIGHT give you enough range, but of course I defer to Bob on that.</p>

<p>Another possible solution might be to have your main flash off to the side and to snoot your on-shoe flash somehow to avoid light spilling directly to the front of the camera (which would light up the detritus). If you're using a G12, perhaps there is some way to mount a reflector to the camera or perhaps to the outside of the underwater housing.</p>

<p>I have never seen a wireless flash underwater setup in real life. There is a reason why good UW setups involve either a spotter or two with external ligths (non-flash) or a flash or two on arms attached to the main housing. Water is such an enemy of equipment that keeping it simple is the only way to go.<br /> Radio vawes and "underwater" don't really mix: salt water is a very bad conductor of radio waves even for very (and very, very...) low frequencies, which makes it not practical for photography. <br /> Water absorbs IR so IR remotes might be not a great way to go, either.<br /> I suppose some optical slaves can be used but IMO it is a very cumbersome way of making sure that everything that can go wrong actually will: from communication to positioning to UW enclosures - you name it.</p>

<p>BTW, should you decide to dive, scuba or snorkel with anything larger than an UW P&S make sure that you know the ropes: a big UW housing can do some really nasty things to ya!</p>

thanks for all the advice, it looks like I wont be able to go like a Porsche in a VW...