Home Made LED light to share

[Craig Turner]

Hi All

I just thought I would share my experiences of the LED Lamp we have been working with over the duration of the 08-09 wedding season. When my wife was pregnant last year we thought it was time to replace the old camera light which was a home made 50watt halogen running of a massive 12 volt sealed lead acid battery.

We wanted to move to an LED lamp but had been unimpressed by what is available. I.e. Crap colour balances, too expensive, poorly diffused.

My friend is an electronic engineer and he is right into mountain biking. He has been messing around with high intensity cree LED's for use while riding and they absolutely rock. They consist of 3 LEDs on a PCB , a LED driver and an optic. He ended up producing a bunch of units for his friends as they cost about $150 to build and were out performing the commercial $800 bike lights. They actually hurt your eyes looking into them like a welding spark.

Anyway long story short. I found out the LED's also came in also came in varying colour balances including a 3.5k flux and I ended up building one for use on camera. It utilises two assemblies so a total of 6 LED's,

For power my mate uses Rechargeable 6volt remote control batteries. I kind of wanted a cleaner looking and quick swappable battery set up. I hacked up an old sony video 8 camera and used the battery plate from that. Then just got some cheap ebay replacement batteries. The numbers are saying I should get 1 hour 10min out of each battery but for wedding use I have been yet to get to the second battery.

Overall it is about 10% brighter that an MR16 globe. Only downside is... they run hot, very hot with extended use. Other problem is when you switch it on it causes almost a complete VHF blackout, this is my fault though for not shielding it properly, it is a little better now I have made some adjustments but it really needs internal shielding. It doesn't affect any of our radio mics so I haven't got around to fixing that yet.

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[Dave Blackhurst]

Nice homebrew light - looks to have some serious punch, unlike so many of the LED lights that seem to drop off fast (no throw). Might have to look into picking some of those up and experimenting.

Just wondering where your heat is coming from - LED's are generally fairly low on thermal radiation, so I'm surprised to hear you're getting a lot of heat. Is there some circuitry in there that's the source? I'd think a good tinfol wrap would reduce or eliminate your RF issues, but then heat might be more of a problem.

[Lukas Siewior]

Craig - do you have any control over the power and output?

Would you be able to share a list of parts you used (or more detailed instructions) for others to copy your design? Or maybe you are taking orders???

[Chris Harding]

Hi Craig

Neat!! I actually looked at the cree units and eventually decided on using individual 10mm LEDs On my DIY site I have pics of both a 5mm and 10mm model and both use warm white LED's which the cameras are very happy with at weddings

http://www.softweigh.com/video/diy.html

I tend to use the panel more often now as it has a pretty good output and I have the LED's wired in two banks of 24 so you can switch power levels. The lite panel uses 1440ma with a 12v Li-Ion CCTV battery so it lasts a good hour and I have now made it so my Stedicam LCD monitor uses the same batteries so I have common battery packs.

Chris

[Dana Salsbury]

Hi Craig,

I use LitePanels with the four AA batteries. The gain control (dimmer) is essential, as well as the easy flip gel. It's super light, but my complaint is that it casts light to the center of my filming area, but I'm shooting widescreen, so the left third and right third are dark. If you could build something that was wide with an easy switch amber gel for indoor shots along with a dimmer, that would be amazing.

Oh -- also utilizing eight AA batteries instead of four, as the LitePanel dies out way too quickly. If you built something like that and gained a forum/cult following, I bet you'd sell quite a few, since you are right that there isn't a lot of good stuff out there.

[Chris Harding]

Hi Dana

As far as I know the LitePanels use 5mm LED's and they have a fairly narrow beam angle. I switched to 10mm LED's which each have a beam angle of 60 degrees so a 16:9 cam view is nicely covered and evenly too. You can actually buy the 10mm LED's with a built-in gel inside the chip which gives each LED a colour temp around 3200K Dunno if you know but all LED's emit very high colour temp light in the blue spectrum around 7000K+++ and also have a mask in them to produce "white light" which they estimate at 6400K. All my light-assisted shots are at indoor receptions ("The couple will now have their first dance"...and all the house lights are dimmed to almost zero!!) I find that the cameras are happier balancing the lower temperature so I stuck with the warm white rather than use a gel. Of course if I needed a fill in daylight I'm stumped!!!

LED's have an optimium working forward voltage of 3.4 so ideally your battery pack needs to be just a tad higher than multiples of 3.4 otherwise power is simply wasted as it's dissipated thru resistors. ie: 7.2 is good as you are only "wasting" 0.4 volts 7.2 - (3.4+3.4)

If you do decide to get one made try for a nice wide angle LED as most LED replacements are designed as domestic downlights which are spots!!!

I see that B&H sell BIG litepanels too!!! Lot's of $$$$ but very efficient!!! At the moment I stick with 3 x 28w CFL lamps in a softbox for speeches as they run cool and give plenty of light too!!

Chris

[Jason Robinson]

Very slick. I had my friend modify the standard Canon VL-10i light to replace the halogen bulb with a LEd array. 6 leds around 600 lumens and best of all, since we modified the existing canon light, it accepts all canon batteries. So easy to put a low battery in it and still get plenty of light.

He also put some control circuitry in there to regulate the brightness and provide a graceful long tail to the brightness.

[Walt Paluch]

we went to these lights

Microbeam 256

best light on the market with a good price

[Dana Salsbury]

I bought my LitePanel for like $350. They've dropped a lot, but it seems like it would be cheaper to have someone build one and get more of what I want. Are the parts expensive? I would love to have a solution that used 8 AA batteries instead of four, as changing them is a pain, and it sucks to do a long shoot and have perfect light in the beginning and faded at the end. That's a lot of color correction in post!

I also like the idea of not using gels, and instead using a switch or something.

[Chris Harding]

Hi Dana

My 48 x 10mm LED Panel cost me under $50 to make!! You can get the LED's on eBay for around $30 and I prefer to use a Li-Ion 12v battery pack which I also got on eBay for $15.00. Yes AA rechargeables are a pain to use!!!! that's why I went with the single pack which just clips on the back. All I have done is divided the LED's into two banks of 24 and switch either one or the other. By switching rather than dimming you avoid any colour shift if the battery is low and you are using a dimmer control!!!

Here is a pic to give you an idea of the layout

Chris

[Dana Salsbury]

What do you think about diffusers with LEDs? They seem to created their own diffusion by being spread out on a board. I don't like diffusion because it reduces efficiency, but it softens skin tone so much that it's worth it.

The AAs are very light, which is part of their appeal for me. Are the Li-Ion 12v battery packs as light?

You have a switch, then, that turns on every even bulb for cooler color temp and odd for warmer color temp? Do you have another switch for dimming? I think a dimmer knob would help dial it in more precisely.

[Taky Cheung]

Originally Posted by Dana Salsbury

Hi Craig,

I use LitePanels with the four AA batteries. The gain control (dimmer) is essential, as well as the easy flip gel. It's super light, but my complaint is that it casts light to the center of my filming area, but I'm shooting widescreen, so the left third and right third are dark. If you could build something that was wide with an easy switch amber gel for indoor shots along with a dimmer, that would be amazing.

Oh -- also utilizing eight AA batteries instead of four, as the LitePanel dies out way too quickly. If you built something like that and gained a forum/cult following, I bet you'd sell quite a few, since you are right that there isn't a lot of good stuff out there.

Dana, I felt the same way about LP micro. I paid $340 for it. Instantly, need to get a replacement because the battery compartment kept pushing the batteries out. Then the dimmer switch broke. But the worst problem is the light output is not as what they claim. It's really narrow and not bright (get worst after using the gel). 4 AA batteries last about 45 min.

[Chris Harding]

Hi Dana
The Li-Ion pack weighs the same as equivalent Ni-Mh cells ..I actually opened a pack and inside is 3 strips of Panasonic cells with tiny circuit boards.

The Li-Ion pack weighs 5 ozs and measures 4" x 2.5" x3/4" ...they are sold on eBay as CCTV battery packs and mine are 1800mah...less than $20 including a charger!!! Believe me they are far better to use than AA cells..I have had a battery box spill open and scrambling allover the floor "chasing" batteries is not for me!! An added advantage is that I use the same packs on my Stedicam LCD monitor so they are interchangeable!!

All my LED's already have a 3200k mask inside the chip so the output id "warm white" which matches the lighting at reception venues well. You might need a higher temp to use it for outdoor fill but at the price you could afford to build one for indoors and one for outdoors!!!

Whether you use one LED or 48 LED's the colour temp remains constant as each chip is independent!!! If you reduce the voltage with a dimmer..it still stays constant until the LED reaches it's threshold voltage and stops working!!! I just switch a top bank or bottom bank!!

Chris

[Dana Salsbury]

Thank you Chris for your advice. It sounds like what would work best is a 16x9 shaped light 8-10 inches wide. Every other row would be warm. It would have a two way toggle: warm and cool. I would have a dimmer/on knob. It would also have some long throw LEDs on the edges for the far-away shot of couples on the dance floor -- those would have their own on/off switch. The battery pack would be part of the unit and the whole thing would plug in.

A built in diffuser would be nice too. I don't understand how diffusers affect color temperature though.

Thoughts?

[Chris Harding]

Hi Dana

Aha!! I see what you are getting at!! Use 24 x warm white LEDS and 24 cool white LEDS so you can switch between 3200k indoor use and 6400k outdoor use. By alternating in LED's you would still get a fair coverage!! I find that even with the size case I'm using I get very little light loss on the edges My bank is 8 LEDs across and 6 down to cater for a 16:9 with is slightly wrong. To get a 16:9 aspect on the panel you actually need 60 LED's (10 across and 6 down which would give an aspect of 1.6666 which is close enough to 16:9

I have no idea why diffusers are used as LED's create a soft light already??? However if you look at the modules that Craig is using they do incorporate a reflector and some even have a lens which would give you a harder light. I find there is little or no shadows on my footage using the light which means it must be fairly soft. The only "diffusers" that would change colour temp would be the ones you see on commercial units that incorporate a yellow/amber gel in them to drop the colour temp. A clear white diffuser shouldn't change the temperature at all!! Due to the lack of physically temperature when the led's are running you can actually use anything as a diffuser if you need one. The whole bank gets very mildly warm at the most !!

Chris