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Thread: Macro Ring Light

  1. #1

    Default Macro Ring Light

    Here is my take on a macro ring light. The concept is not new but for me need and availability have handily come together. I just bought an Olympus TG5 and housing; two of its features are super close macro and a fast frame rate, up to 20 fps. I do not have strobes but it is evident that no flash will recycle that fast.
    Recently a number of ring COB LEDs have been available, popularly used on car headlights and often termed ‘Angel Eyes’ from a well known online market place.
    I have not found a spec sheet and the ones I purchased came with a buck driver giving 350mA at ~9V from a 12V supply for all sizes from 60 to 120mm. This can easily be replaced with a XL6003 based boost driver (available from the same place) giving 650mA. I have coupled these with 80mm and 90mm ring with 21 and 22 LEDs (sets of 3 in series) which drive each LED at 30mA. Power comes from two 18650 to give 7.4 V controlled by a clickey switch and logic level MOSFET.
    Drawing about 12W I recon the setup is good for 1000 lumen.
    Photo show the set up, it is a bit crude, but has done a good job as a ‘proof of concept’ Mk 1.
    Other photos show it in action and what I think may be the photo I was taking at the time. It takes more than a nice camera and a bright light to get the perfect photo but I think it shows its capabilities. This little shrimp was on a Feather Star and demonstrates the even lighting while the Cuttlefish was from a series of shots of it while constantly moved and changed colours and shows the benefit of being able to pick the perfect (well best) frame of a swimming subject from a series of shots when neither the subject or photographer are perfectly still. (Beware of shooting at 20fps, you are left with an awful lot of deleting to do).
    I now fancy that the LEDs can be driven closer to 60mA, and have tested a ring for a couple of hours at 45 mA, which should give a 50% boost in output.
    I would be glad to hear from anyone who knows the true max current of these COB lights.
    Construction is pretty obvious with bonded Acrylic, bolts and O ring.
    Mk2 is already under construction with a more ‘compact and finished’ look and hopefully brighter 45mA LEDs.
    Mk3 might go for the ‘full’ 60mA and a third ring which should push it up to nearer 3000 lumen.


    OK I will post photos when someone tells me how to post from Google Photos.

    Rod


  2. #2
    Flashaholic* DIWdiver's Avatar
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    Default Re: Macro Ring Light

    Sounds like a nice project. I'm anxious to see pictures.

    First you need to have pictures somewhere you can link to them. The click the 'insert image' button and paste the link in the window that comes up.

    Remember, forum policy is that pictures posted this way must be a maximum of 800 x 800 pixels. You might need to use an editor to crop or reduce resolution before posting.

    If you want people to be able to see the optimum picture resolution, you can paste a link to the full size picture directly in your post.

  3. #3

    Default Re: Macro Ring Light

    Thanks DIW, Sorry about the ineptitude.
    I hope this linkg will take you to the photos.
    https://photos.google.com/album/AF1Q...UjP6hyFMo4EkD8

  4. #4
    Flashaholic* DIWdiver's Avatar
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    Default Re: Macro Ring Light

    Nope, link doesn't work.

  5. #5

    Default Re: Macro Ring Light


  6. #6

    Default Re: Macro Ring Light


  7. #7
    Flashaholic* DIWdiver's Avatar
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    Default Re: Macro Ring Light

    Nice job!

    How big is that cuttlefish? It looks smaller than I thought they usually are (maybe juvenile?).

    Did you etch or mill that circuit board yourself? I haven't seen one of those in a while.

    In most circumstances, the LED current is limited by die temperature. As long as you can keep the dies cool, you can keep cranking. To that end, mounting on copper or aluminum with good thermal path to the water would allow for much higher currents.

    Basically, the higher the die temperature, the faster the LEDs will degrade. Cheap ones will degrade faster than ones from quality manufacturers. Given that the life expectancy of your ring light is probably tens or hundreds of hours, you can tolerate substantial degradation of the 10,000+ hour 'standard' life expectancy.

    Unfortunately, without good data from the manufacturer or experience with those particular emitters, it can be difficult or impossible to put numbers to these ideas.

  8. #8

    Default Re: Macro Ring Light

    Thanks.
    The Flamboyant Cuttlefish was 2 or max 3 inches overall which seems to be standard for that species. Cuttlefish are a novelty to me and most we saw on this trip (to Lembeh) were much smaller, just a half or one inch.
    The circuit board was engraved using my minimill which I have recently converted to CNC.

    I take you point on the LED cooling, it occurs to me that as you up the current the efficiency drops off and you get more heat and less light per mA so I guess I will stick at 45mA.

    Rod

  9. #9
    datiLED's Avatar
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    Default Re: Macro Ring Light

    Cool light project, and awesome photography! I'd love to see some more pictures of the light and underwater discoveries.
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