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How do you assess the power output of a video light?


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#1 ians.moyes@gmail.com

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Posted 08 November 2012 - 02:46 PM

I'm looking to buy a pair of UW lights to go with my Gopro Hero 2.

I keep seeing lights measured in Lumens and LUX.

Is that the same?

I know that more is better but what power do I "need" for the light to be useful?

I saw a cheap light that I thought might get me started with 640LUX output. http://www.ebay.co.uk/itm/400280134437

Is that a useful starter light or is it just a toy to waste money on?

Thanks in advance for any advice you can give. :-)
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#2 John Bantin

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Posted 09 November 2012 - 01:44 AM

Lumens is the measurement of light emitted whereas LUX is the number of lumens per square metre arriving at the subject. For a given lamp to subject distance, LUX is a more relible measurement for comparison because it takes into account the efficiency of the reflector but this has to be compared against the diameter of the beam at that distance too.

Geddit?

Edited by John Bantin, 09 November 2012 - 01:44 AM.

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#3 ians.moyes@gmail.com

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Posted 09 November 2012 - 03:41 AM

Geddit?


Goddit! :-)

Thanks John. So, is 640LUX a usable device or just a worthless toy? If it's useful, why is it so cheap? I've been reading about SOLA 1200s at GB£300 and more. :-s
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#4 John Bantin

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Posted 09 November 2012 - 05:37 AM

It's probably made in China. I cannot say why it is otherwise so priced without having one in my hand. I did recently use a (cheap) lamp that had a lithium-ion battery that, when it flooded, became quite exciting because it had no over-pressure valve.

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with. Did you know you can now get Diver Mag as an iPad/Android app?

 

#5 adamhanlon

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Posted 09 November 2012 - 01:17 PM

Whilst not strictly germane to the OP's original enquiry, lighting GoPros is a difficult task. This is because they have wide lenses, and do not work well for macro/close up. This means that if your lighting is to be effective, you really need big powerful lights to light the whole scene at some distance away from the camera. You then end up in a situation where you are spending $3,000 plus to light a $400 camera!

My suggestion would be not to bother with smaller output lights, just to shoot using ambient.

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#6 SPP

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Posted 10 November 2012 - 10:45 AM

Ian, night dive is the only time my GoPro HD2 can be lighted cheap......he he he. Cheap means 2 x 1300 lumens at medium FOV 1080p, as Adam put it ....much....... more money for the light.

If you dont mind a "bomb" but electrically knowledgeable, try this :
http://www.easylight...light_p762.html

Its a bomb when flooded as it has no vent valve, well Sola 4000 does not have a vent valve too, but this Archon battery is 12 x 18650 cell, so it is a very potential BOMB-to-be if flooded.

Get HD3, do wide angle shallow water or get URPRO-SRP color correction filter for HD3 ( they will make it for sure ) if you do deeper, its will be fun and will blow away many more expensive cameras. Go to Gopro user forum, they talk of HD3 a lot there and some UW test going on which looks real good for no assistance from a light source in such crappy viz.

Have fun shopping..........
.
.

Edited by SPP, 10 November 2012 - 10:45 AM.


#7 John Bantin

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Posted 10 November 2012 - 10:59 AM

Its a bomb when flooded as it has no vent valve, well Sola 4000 does not have a vent valve too, but this Archon battery is 12 x 18650 cell, so it is a very potential BOMB-to-be if flooded.



Done it!

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with. Did you know you can now get Diver Mag as an iPad/Android app?

 

#8 SPP

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Posted 11 November 2012 - 04:40 AM

Hi John,

With your massive experience, please tell me about your flooded lights with n without vent valves which have exploded, be it UW or in air.
I need the database, such info is priceless he he he.

I wanted to buy this and install on the Archon :
http://shop.dev-pein...ruckventil.html

Above is smaller than this below, the alumimum one for shallow depth operation aka 100 meters :
http://www.prevco.co.../PressureRV.htm

Still looking at suitable spot to locate it though. I really like the Archon light for its smooth very wide angle beam and replaceable batteries.

Many Thanks
SP

#9 ChrigelKarrer

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Posted 11 November 2012 - 06:02 AM

I used one of mine 4000 Lumen 120° LED light on several cameras, including my Gopro 2 and the 120° beam cover most of the scene, but:
Even in "crystal" clear Sardinian waters a 120° beam 4000 lumen dive light will NOT illuminate anything - except reflecting things - more far than 2 ft during daylight,
while they work nice during night or wreck/cavern/cave dives illuminating big dark spaces.
As AdamHalon already mentioned, due the 180° FoV the GoPro is very picky to use with torches and a more concentrated beam will penetrate more but
create ugly hotspot's in the pictures/videos and the GoPro 2 is not able to focus very near.
LUX is the most useful value for comparing (dive) lights but most of the manufacturers use Watt or Lumen instead of Lux.
A 4000 Lumen torch emit 4000 lumen of light, BUT depending of the reflector or beam width the 4000 lumen may not arrive on the object because of the beam with.
The 160 lumen focus lights in my Z-240 strobes are brighter than the 4000 lumen mangrove light because of it's narrow beam.
Chris

Edited by ChrigelKarrer, 11 November 2012 - 06:08 AM.

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