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Thread: LED Diffusion Lighthead for Omega D5

  1. #11

    Re: LED Diffusion Lighthead for Omega D5

    Jim! 2nd Saturday! Kirk, always welcome.

  2. #12
    Jim Sidinger
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    Re: LED Diffusion Lighthead for Omega D5

    Quote Originally Posted by Chauncey Walden View Post
    Jim! 2nd Saturday! Kirk, always welcome.
    Whoops! It's that thick Costa Rican air! Yes, 2nd.
    (A contrite) Jim

  3. #13
    Randy Moe's Avatar
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    Re: LED Diffusion Lighthead for Omega D5

    Very good design and execution.

    The parts are still available.

    I missed this as I was not on the forum for months at that time.

    Great post!
    TIN CAN COLLEGE

  4. #14

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    Re: LED Diffusion Lighthead for Omega D5

    Are there any issues using a conventional timer with LEDs? Start-up lag, flashing, etc?

  5. #15
    Jim Sidinger
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    Re: LED Diffusion Lighthead for Omega D5

    Good Questions.
    1. No problems using conventional timer. Current load on timer very low due to LEDs and, in my design, less than a conventional 60 watt bulb.

    2. Yes, there is a 'Start-up' lag. In the case of the LEDs and driver I used, it worked out to about .7 seconds. As a result, I need to add .7 on my timer to my calculated total time for the exposure. Once they are on, the time to full luminosity according to the specs is only a few milliseconds so I have not needed to adjust for that. The .7 second adjustment is a bit of a pain, but overall the advantages of LEDs make it very much worth it to me.

    3. I have noticed/measured no flashing. Once the LEDs are on, they seem to stay at a constant luminosity.

    Unasked:
    Do you have to 'warm' the LEDs & driver up with some 'on time' before the actual exposure?

    My Answer:
    I have not added any warmup for each exposure. I was told, by the manufacturer, that the first time you turn on the LEDs after some hours of disuse, there may be a need to have them on a few seconds to reach full luminosity. However, since I usually have them on for that time (at least) to confirm proper focus of the negative at the start of each darkroom session, I have not done anything special for this issue. Nor have I done any preliminary 'on cycles' for subsequent exposures within a darkroom session. Seems to work fine.

    I am still using the Version 1 of the lighthead that I documented in this post - even now. I had expected I'd need to build a V2 to get to a final, fully usable one but so far, so good. Even blind pigs...

    Hope that helps, Jim
    Last edited by denverjims; 10-Nov-2018 at 17:26. Reason: adding more detail

  6. #16
    Jim Sidinger
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    Re: LED Diffusion Lighthead for Omega D5

    Quote Originally Posted by Randy Moe View Post
    Very good design and execution.

    The parts are still available.

    I missed this as I was not on the forum for months at that time.

    Great post!
    Thanks, Randy.
    Best, Jim

  7. #17

    Join Date
    Jul 2018
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    19

    Re: LED Diffusion Lighthead for Omega D5

    Quote Originally Posted by denverjims View Post
    Good Questions.
    1. No problems using conventional timer. Current load on timer very low due to LEDs and, in my design, less than a conventional 60 watt bulb.

    2. Yes, there is a 'Start-up' lag. In the case of the LEDs and driver I used, it worked out to about .7 seconds. As a result, I need to add .7 on my timer to my calculated total time for the exposure. Once they are on, the time to full luminosity according to the specs is only a few milliseconds so I have not needed to adjust for that. The .7 second adjustment is a bit of a pain, but overall the advantages of LEDs make it very much worth it to me.

    3. I have noticed/measured no flashing. Once the LEDs are on, they seem to stay at a constant luminosity.

    Unasked:
    Do you have to 'warm' the LEDs & driver up with some 'on time' before the actual exposure?

    My Answer:
    I have not added any warmup for each exposure. I was told, by the manufacturer, that the first time you turn on the LEDs after some hours of disuse, there may be a need to have them on a few seconds to reach full luminosity. However, since I usually have them on for that time (at least) to confirm proper focus of the negative at the start of each darkroom session, I have not done anything special for this issue. Nor have I done any preliminary 'on cycles' for subsequent exposures within a darkroom session. Seems to work fine.

    I am still using the Version 1 of the lighthead that I documented in this post - even now. I had expected I'd need to build a V2 to get to a final, fully usable one but so far, so good. Even blind pigs...

    Hope that helps, Jim
    I asked about the timer and flashing because I set up a small electroluminescent panel to flash paper and had to add a dummy load or the panel would pulse when off as long as it was connected to the timer. Also have a lag, but I have been able to compensate since the flashing time is always the same--I only use one paper right now.

  8. #18
    Jim Sidinger
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    Re: LED Diffusion Lighthead for Omega D5

    Quote Originally Posted by Pieter View Post
    I asked about the timer and flashing because I set up a small electroluminescent panel to flash paper and had to add a dummy load or the panel would pulse when off as long as it was connected to the timer. Also have a lag, but I have been able to compensate since the flashing time is always the same--I only use one paper right now.
    Pieter,
    No, I see no flash of any kind either during or after timer operation with my setup. The timer I am using is an old Ilford DT600 (previously a Creative Phototronics Touch Timer). (Note: The one picture I found on the web (below) is of the programmable version. The one I am using is the straight, non-programmable one.)
    Click image for larger version. 

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    Sounds like you did figure it out, though. I'm no electronics guru but sounds like the timer you are using was set up to operate loads much larger than your panel. The additional load you added probably compensated for this. Maybe someone else, with more expertise on the subject, might have better insight.

    Finally, the .7 seconds lag in my setup is, to my best perception, constant. I just don't know if this interval is a general constant with that combined type of LED and driver or if it would vary by driver or by the number of LEDs one would use in the configuration.
    Best, Jim

  9. #19

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    Re: LED Diffusion Lighthead for Omega D5

    Im using the rosco filters with my cold light. They're very thin, I laminated them so they'd be nice flat in my holders. My only disappointment with the filters I mail ordered from B&H, they were in terrible condition, wrinkled n damaged as if they were used as floor mats in their warehouse. I had to go to the store to get nice ones.

  10. #20
    jp's Avatar
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    Re: LED Diffusion Lighthead for Omega D5

    The .7 second lag might be the power supply If your timer were downstream of that, there might not be lag.

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