An Interesting Problem – Surface Color Variations


A member of the Community, Cameron Ware (also known as @VisualWorshiper on Twitter) encountered a pretty interesting problem this weekend while lighting a gig.  Check out this video:

My guess is that one of two things has happened – either a UV field has somehow made its way into the beam, or that surface has something about it that surface being illuminated is reflecting that crazy UV tint. What do you think? Please leave a comment in the Comment section below, let’s solve this problem together!

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  1. Yeah, the types of surfaces reflecting that blue color does seem to be characteristic of a UV light source. I don’t know if you swapped out the filters between the two lights (which would tell you if it’s the filter or the lamp that’s making the difference), but I have a suspicion that the lamp is what’s causing the UV to be introduced. From what I recall, many red filters do let some UV spectrum through. Again, you’ll have to swap the filters (or the bulbs) to know for sure, but I do suspect it’s the bulb as opposed to the filter that’s introducing the UV.

  2. I’m looking forward to what people think is causing this, particularly the more scientific answers.

    My guesses (without knowing much about the materials & finishes of the surfaces being lit)
    1 – Something with the paint pigment, surface reflectance, or surface materials / construction could be causing the abnormality.
    2 – Something relating to the CMOS sensor (maybe auto white-balance inconsistencies).

    Now, these are simply guesses (no science backing, no PhD involved, just humble opinions…)

    -Joe F.

  3. Weird……It has to be fixture based right? Since the problem stays with the fixture and not the banner.

    Could the glass in the fixtures be different if they are OEM….Different batch?

    Or maybe the UV filters in one of the fixtures is cracked or something…

  4. 2 things I suspect…

    I would assume that the banners have a UV treatment to limit degradation. Most banner manufacturers I’ve dealt with do this.

    With that in mind, my guess is that the dichroic filter is reversed in the field defeating its own UV treatment.

    What is the fixture being used? There may be other options for the lack of UV filter in the source too depending on the answer to that.

  5. Could it be the orientation of the material in the banner that makes the difference- upside down relative to the other side??

  6. A few details I forgot to mention in the video:

    This is the 2nd show, where the setup was the same, and we didn’t have this problem. It has to be fixture related.
    The units are Elation Design Wash 250 – and yes, I suspect the UV filter in the magenta fixture has failed somehow.. I’ve used these wash units for a few years and have never seen this happen, but very odd.

    I’ll open the fixture up next show date and post what I find!

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