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Physical properties of studio lights?

Discussion in 'Studio Lighting Forum' started by esha3D, Jun 4, 2018.

  1. esha3D

    esha3D New Member

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    Hello, I'm new here and I have a somewhat unusual question:
    I'm trying to transfer the characteristics of real light sources to the virtual lights in a 3D rendering program.

    A softbox is easy to create in a 3D program, I just set the light to emit across a surface instead of from a single point.
    But I'm struggling a bit with the other lights like umbrella and beauty dish. I've done research on the web but I didn't find the information I need. The explanations I found concentrated on how to use these lights and not on the characteristics of the light they create. I'm interested in things like falloff and how hard or soft the shadows are. The examples I found always are portrait shots and mostly have other light sources mixed in which makes it difficult for me to filter out the information I need. I'd need to see how the light looks when pointed straight at a grey wall. Then I can compare the effect of the real light and the 3D light and make adjustments accordingly.

    I'd really welcome any advice where I could find this information...
     
  2. Roger S

    Roger S Crazy Canuck Administrator

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  3. Minor Problem

    Minor Problem Always on Premium Member

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    A couple of starting points, a brolly or softbox act as a large source with gradual fall off because the light emits in a wide beam from every point of the entire surface, shadows are soft and partially filled. A gridded soft box acts as a mass of point sources, the light is more directional, the shadows aren't quite so soft and are deeper and the falloff is steeper and more controllable.
     
  4. oldgeezer

    oldgeezer Always on Premium Member

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    Light is light and apart from anything modified like a lamp shade, all light sources act the same.

    The thing that you are after is what is focusing the light.
    Easy way is to get a light source and shine it through different shapes and distance from that shape will determine what it will look like.
    Nothing to do with light as such, more how you focus it or let it spill.
     
  5. MikeB

    MikeB Always on Premium Member

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    There is a wealth of information available for 3D modeling of luminaries of all sorts. The issue I believe that you have is that the light modifiers are proprietary designs and each model modifies light in a different manner. Even something as simple as a beauty dish will have variations based on size, manufacturer and model - some are shallow, some are deeper. Even the simple light box will vary with size, diffusion panels, reflector, light source, etc.

    The characteristics of a particular light source will vary from light to light and can be dramatically altered by any modifiers the photographer chooses to use. Studio photographers tend to use a light meter to measure how much light is actually produced at the subject and then work from there to achieve the quality of light they desire.

    I suspect that your best bet is to find the light and modifier you want to model and measure the characteristics of that light source and modifier.
     
  6. esha3D

    esha3D New Member

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    Yes and no ;)
    I looked up the specs for a beauty dish and modeled it, and it did work, however the render times for this light were very long. I want to try if I can tweak the parameters of the light itself to create a similar lighting without building geometry around it.

    Light manufacturers do offer ies files for download to be used in 3D renders, but those are mainly for decorative lighting. I don't know if any of these light profiles would match the output of a light source used in studio photography?

    [​IMG]


    This is very useful information, thank you! Does a brolly create the same (or similar) lighting as a softbox or are there noticeable differences?

    Exactly! My problem is that I don't know exactly how the different light sources focus the light. For example, I can't really pin down the difference between the light created by a brolly and the light that comes from a beauty dish.

    I rendered out a series of examples. These different effects were achieved by changing the light's settings. I wonder if I could replicate the effect of the various light modifiers by combining these settings in the right way.

    [​IMG]
     
  7. Phill104

    Phill104 Always on Premium Member

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    Take a look at the videos of Gavin Hoey on YouTube. A few of them he sets up various lights on his studio wall showing quite clearly the projections the give.
     
  8. chaz

    chaz Always on Honorary Life Member

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  9. esha3D

    esha3D New Member

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    You're right, Gavin Hoey's videos are very instructive! Those and some others on the Adorama channel gave me the info I needed.
    :thanks:
     
    Phill104 likes this.

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