Wednesday, July 1, 2015

Large LED Panel Light Testing

I've recently wanted to do more videos and take better pictures for the blog, but I've been limited by my lighting.  At the moment most of my photography is done under 2 LED tube lights that illuminate the whole room.  They appear bright, but in reality there isn't enough light for photography, and although they're not as bad as point sources, I get long straight reflections on shiny objects in my photos.  What's needed is a large, bright, distributed light source that I can place above my desk.  It should remove most reflections, and also reduce shadows when working.  I've previously played around with a small LED light panel and it seemed a larger version would be perfect for the job.  After looking at all the options available on AliExpress (there are a lot),  I finally choose a single large 80W panel.

LED Light Panel
80 Watt LED Panel
This thing is massive.  It's 600mm x 1200mm x 8mm, the size of a standard ceiling tile you'd see in any Dilbert style office.  According to the specs it's an 80W panel with an output of 8000 lumens.  That gives a luminous efficacy of 100 lumens per Watt, which is a pretty standard value for white LEDs.  It has a reasonably high colour rendering index of above 80 to ensure faithful colour reproduction.  The colour temperature is somewhere around 4000K, which is the colour I'm most comfortable working under.

Electrical Specs
LED Panel Specifications
I was a little nervous ordering something so large and expensive from China.  When picking up the panel from the post office it became obvious my concerns were valid.  It was shipped in a box with the power supplies and they were allowed to freely move around.  It seems at some point a weight was placed on one end while the panel was resting on the power supplies and it was bent on the long edge by about an inch.  No problem though, I was able to easily bend it straight.

LED panel light
Meter ruler placed along the edge of the panel
LED panel light
Maximum deviation of the panel from straight
What's the point of buying something if I don't pull it apart?  After removing the back plate the construction method became obvious.  There are two white LED strips on the long edges of the panel, each containing around 200 x 200mW LEDs.  The panel uses the same method to get light from the edges to the face of the panel as the smaller light described in a previous post about LED panels.  There are two large thin sheets of foam to keep the plastic layers firmly pressed together with a return wire running on top of them.

LED panel light
LED panel with back removed face down
LED panel light
LED panel with back removed lit up
Pattern on back layer to disperse light
The frame is flimsy aluminium that's spot welded in the corners.  From what I can gather each part isn't overly strong but when assembled they make a fairly rigid product.  As usual in these lights, the wiring isn't great.  There isn't any significant strain relief and it looks like constant flexing of the cables could cause the solder joint to fail.
LED panel light
Welded corner and wiring
I wasn't willing to completely disassemble it as I think it'd be easy to damage if I wasn't concentrating.  I was however able to see the LED strip sandwiched in between the frame and the optical plastics.

LED Strip
LED strip
The light comes with two power supplies, which is disappointing, I would've rather paid less and bought separate power supplies as I don't intend to use these.  They're a no frills standard LED driver.  They take a multi voltage mains input and can drive an LED string at 30 to 40 Volts at 900 mA.  The astute among you may have noticed that's only a maximum of 36W.  So it's likely they're slightly underdriving the panel, which isn't a bad thing.

power supply
40W - LED driver module
I balanced the panel between the backs of two chairs to take some test shots.  I think they turned out OK.  There aren't too many severe reflections and the light seems bright and evenly distributed.  Even with the crappy point and shoot camera I use, the colours seem vibrant.

Pencil Case
Case that holds my metal files
Raspberry Pi
DC - DC converter module
It wouldn't be right If I didn't use this panel light to pretend to be a doctor and look at some X-rays.  Luckily I had some laying around from few years ago.

Coronal slices of my sinuses
Look at that photo.  Ain't I a handsome devil?

The inside of my head
Overall I'm happy with the product.  Yeah, it could have been packed better but it's not a major problem and you forget about that as soon as you see it working.  It really is quite impressive to turn this thing on have it basically blind you.  The next step is to make some sort of frame to mount the light above my desk.  I think welding may have to be involved.

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