1500 lumens, wide angled, filming & photographic light - Interested?

Rob

Rob

Well-known member
I'm looking at building a batch of dual P7 LED lights to use for light painting (S.I.T.) and am just wandering if anybody else could be interested in purchasing one, so i get my batch sized correctly. They will have not have any reflector on the LEDs so will have a ~180 degree spread.

Prototype build:
3044862439_45de55d35b.jpg


Final system will be similar to the protoype but fully housed (water/mud resistant, not proof!) and be adjustable in output (~1500 lumens - ~525 lumens - ~75 lumens). Price is looking to be about ?100, but depends on people's battery requirements and order sizes.

Either reply or just PM me if you "could" be keen.

Rob
 
Stupot

Stupot

Active member
Hey Rob,

I 'Could' be interested mate.

Keep me updated  (y)

Cheers

Stu.

PS. Congratulation on Descent cover, got there in the end, bet Shone is after you now  ;)
 
nickwilliams

nickwilliams

Well-known member
Stupot said:
PS. Congratulation on Descent cover, got there in the end, bet Shone is after you now  ;)
Click to expand...

I'm interested to note that the back cover explains why we seem to have a shortage of gloves at work....
 
Rob

Rob

Well-known member
Thanks for the PMs and responses so far.  (y)

A couple people have been asking for examples of photos taken using just one of these lights. Here's four, for all of which the light was stationary.

3148981810_6f8bdbdd20.jpg
3010166604_1e41198b8a.jpg


3147858129_d4013d772f.jpg
2798731577_48f510eef3.jpg

(in this last one there is also a Tesco torch from behind providing a bit of backlight)


Also it was used a lot for the filming of the Titan streamway breakthrough... (although so were a couple "spot" lights at times)

http://www.youtube.com/v/2in9fVaI5XI&hl=en&fs=1​

 
Katie

Katie

Active member
I'm interested to note that the back cover explains why we seem to have a shortage of gloves at work....
Click to expand...

I thought you might have already guessed as the size 8's always disappear the fastest.......
 
Rob

Rob

Well-known member
francis said:
The first and third pics are truly awesome!

Which camera do you use?

Francis
Click to expand...

Thanks Francis.
The 1st 3 pics are with a 40d with a 10-22mm lens, the last with a G9.
 
Rob

Rob

Well-known member
pete h said:
What batteries are you thinking of using and what burn times will you get.
Click to expand...
My initial design will be 7.4v li-ion packs, probably 2.4Ah capicity cells. On full wack this will probably last about 40mins. About 2 hours on med. On low, probably around 13 hours.

After 40mins of photography i'm generally getting a bit bored, so this battery suits me. However the light can run on any battery pack between 5.5v and 15v, so i can make it to fit your requirements.
 
Basher

Basher

New member
I Would be interested.
What is the equivalent in watts like a dichroic, to 1500 lumens?
Also any plans to make any with reflectors at all?

regards,

Bash ;)
 
Rob

Rob

Well-known member
Basher said:
What is the equivalent in watts like a dichroic, to 1500 lumens?
Click to expand...
No idea! Geeks...?

Basher said:
Also any plans to make any with reflectors at all?
Click to expand...
None at the present. I'm only making them for photography so they are not helmet mounting friendly.

If you're after spot lights though there are thousands available online that are under 40 quid and plenty bright enough (although probably quite bulky on your head!). Search http://www.dealextreme.com/ for "P7".
 
jarvist

jarvist

New member
1500 lumens is roughly a ~110W incandescent household bulb (~13.8lm/W).
Super high temp halogens with short burnout times can hit 35lm/W, so equiv to a ~40W photographic bulb.

The P7 is given as 90lm/W in the datasheet (though the light is slightly warm at 6300K).

No offence to Rob, but its unlikely to achieve the full 1500 lumens.
These measurements are usually made with outrageous low diode junction temperatures of 25C (i.e. only realised for the first few tenths of a second after turn on), and integrating the whole sphere of light, even if a a lot of it is unused low intensity scatter at the edges.
The data sheet says efficiency is: 95% @ 50C, 90% @ 75C, 85% @ 100C.
Also, it suggests a 130degree cone of light for the 'dome' type P7.

BTW; 100% efficiency (in white, though the colour temperature also has an effect...) is 240lm/W - so we have some way to go yet!
Organic LEDs potentially have far higher efficiencies, and in green at least have already whomped inorganics.

P7 Datasheets, fun reading for the whole family,
http://www.seoulsemicon.com/en/product/prd/zpowerLEDp7.asp
 
Rob

Rob

Well-known member
I knew someone would be able to help!  (y)

I think it may be close to 1500lm. Each LED will hopefully be driven at 2.8A, with a Vf of 3.7v. This = 10.36 Watts. Therefore at 90lm/W that = 932lm. I've got two of them = 1864lm. I'm hoping that the heatsink isn't going to reach 100degC, but assuming it does (85% efficiency) = 1585lm. Right? 
:confused:

And for photography all the light can be used, even the low intensity stuff at the sides.
 
Darkstar

Darkstar

New member
I lost it when you started talking about diode junctions!! :eek:

Rob,
The last two photos you have in the post.  What F-stop and exposure time were you using?  This will give me as much info as I need to know about brightness (y)
Cheers.
 
Rob

Rob

Well-known member
Darkstar said:
Rob,
The last two photos you have in the post. What F-stop and exposure time were you using? This will give me as much info as I need to know about brightness (y)
Cheers.
Click to expand...
Good idea Darkstar...

3148981810_6f8bdbdd20_m.jpg

Exposure: 4 sec (4)
Aperture: f/3.5
ISO Speed: 250
Camera: Canon 40D

3010166604_1e41198b8a_m.jpg

Exposure: 0.067 sec (1/15)
Aperture: f/5.6
ISO Speed: 1250
Camera: Canon 40D

3147858129_d4013d772f_m.jpg

Exposure: 3.2 sec (16/5)
Aperture: f/4
ISO Speed: 250
Camera: Canon 40D

2798731577_48f510eef3_m.jpg

Exposure: 6 sec (6)
Aperture: f/2.8
ISO Speed: 80
Camera: Canon G9
 
Darkstar

Darkstar

New member
Cheers buddy.

I could well be interested in two.  It would depend on the eventual size and weight of the units.  I am not a world class (or even village class) photographer so don't have tribes of people (or even 1) willing to sherpa for me.  My attempts are often preceeded by much begging and choruses of "if I must".  It would be nice to be able to carry just two of these units and the camera + tripod.  Thus dispensing with the large amount of swearing when the fireflies fail to trigger or when a flash swallow dives into a steamway.

Sorry if this is a silly question, but would it be possible to have the light output continuously adjustable across the range?
 
mrodoc

mrodoc

Well-known member
When are planning to go into production. Have a trip to Scotland end of April and would be fun to give the system a whirl there.
 
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