Results 1 to 2 of 2
  1. Collapse Details
    My DIY flexible LED panel light, comments? how to test output and estimate CRI
    #1
    Junior Member
    Join Date
    Oct 2015
    Posts
    12
    Question
    Hey guys!


    I am very new to videomaking, coming from photography, so take it easy on the new guy!


    I recently madetwo flexible back LED panels. I was inspired by a DIY light panel video on youtube but added the flexible panel idea. I wanted to insert the panel into my existing photography modifiers, mainly a brolly umbrella.Honestly I am now wondering about the implications of the LCD color temperature of the lights and CRI for videomaking. I will be using these lights indoors with very little ambient light to mix, interview style stuff. No photography, just video. I am asking if these lights are OK for video (I know not perfect, itís a DIY amateur hour here!).


    I ordered the LED from Ebay (dont groan!) for daylight color. I put all the parts away for about 6 months and just the other day soldered it all together. When I rechecked the LCD supplier a few days ago the lights were then relabeled 3200-4000K lights. I thought they were actually 5500K when I ordered but I soldered them up anyway. I used a reworked (free!) desktop computer power supply for the 12 volts as I would need almost 10 amps per light. I did not want a dimmer, it would add complexity and costs, so I wired it up with two separate banks per light, a high and low concept. The backing is a heavy plastic and I contact-cemented heavy duty tinfoil onto them, for heat dissipation. I can tell you the LCDs do not stick to plastic well, but are fine to the foil.


    Each light has 22 feet of smd 5050 LCDs equaling 396 bulbshere is the link for the bulbs if you are curious. http://www.ebay.com/itm/251707086240I have included pics of the panel, mounted outside the brolly to see how it mouns and inside before turning on.


    I would say total cost is $30 per light, but WOW the soldering tested my patience! No apparent flickering and they ran cool. They are pretty flexible, very lightweight. I may switch to another laptop adapter powersource for portability, but for now the desktop powersupply is fine.


    Performance. I used a super basic light meter app from my phone to measure lux and temp. I am more confident on the lux reading, the temp reading moved around on the meter.https://play.google.com/store/apps/details?id=com.bti.lightMeter&hl=en


    Light outside of brolly, no diffuser: 3 feet: 650lux 3700k6 feet 250lux 3700k


    Light inside brolly, diffused: 3 feet 450 lux 4100k, 6 feet 250lux 3100k


    I had hoped they would be brighter. I have two of these panels for lighting, each will go in a separate brolly for two point lighting.


    So, my questions.


    I would like to try some basic tests.


    Any way to check for flickering?


    Any easy way to estimate CRI to make sure these bulbs are passable? I want to know if I have to gel them or anything.


    I was just planning on using custom white balance and make the best, unless someone points out a major flaw in these lights. I guess I would then buy some LCD Chinese panels. Aputure probably or Yongnuo. they have higher lux specs and color temp.



    My main use will be indoors, little ambient light, interview style. My main concern is shooting at this color temp and how it will effect skintone. Any comments on this issue?



    Again, I am newbie, I know there are a lot of DIY LCD panel posts.





    Thanks!

    Mike





    Attached Images Attached Images


    Reply With Quote
     

  2. Collapse Details
    #2
    Todd Wannabe dory_breaux's Avatar
    Join Date
    Sep 2007
    Location
    Truckee, CA
    Posts
    2,009
    Default
    I LOVE the flex back design idea. I might have to copy you for my timelapse lighting rigs. If you have access to a camera that shoots over 120fps you can tell if you are getting any PWM flicker (doesnt sound like you would because you arent using a dimmer), might even work at lower fps I'm not sure.
    Quote Originally Posted by TimurCivan View Post
    one is french and its different for that reason.


    Reply With Quote
     

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •