Custom glass gobo installation which side to lamp?

Discussion in 'Lighting and Electrics' started by JChenault, Sep 2, 2019.

  1. JChenault

    JChenault Well-Known Member

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    i have a custom glass gobo I am reusing from a prior production. One side is the glass, and the custom part appears to be deposited ( painted or printed) on the other side. The two sides are clearly different ( I think this was a Rosco gobo, but I am not at all sure)

    Which side wants go towards the lamp? The clear glass side or the printed on side?

    Thanks in advance
     
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  2. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Does "upside down and backwards" not apply?
    "So the lamp can read it?"
    Is it going into a "moving light," SourceFour, or 360Q?


    I do hope @GreyWyvern is within earshot.
     
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  3. GreyWyvern

    GreyWyvern Apollo Staff

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  4. Colin

    Colin Well-Known Member

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  5. RonaldBeal

    RonaldBeal Active Member

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    The irony is that while that link says "Multi Layer glass gobos should always have the dichroic layers of glass installed away from the lamp" when I worked for Vari-Lite, they said the exact opposite for their gobos in VL-2s and VL6s (gobos manufactured in house). Certainly, I am sure there are differences in manufacturing between the different gobos, but goes down to "what does the manufacturer recommend?"

    The reason I was given for coated side towards lamp, is that the coating reflected not just visible light but IR and UV, and having that on the lamp side reduced the thermal heating of the glass, where as having it reversed meant that a lot of that energy passed through the glass twice, (once on the way in, and again being reflected out) so impurities in the glass absorbed more heat.

    Just my recollections.
    RB
     
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  6. JChenault

    JChenault Well-Known Member

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    Upside down and backewards does not help in this case ( it is semetrical right to left ). It goes into a moving light ( revolution )

    For now I am putting the “ printed” side away from the lamp

    As the gag is only up for work 20 seconds or so it is probably not a big deal
     
  7. Kelite

    Kelite Apollo Staff Premium Member

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  8. SS Minnow

    SS Minnow Member

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    I was once taught that a gobo image flips every time it passes through a lens, which technically means that you would have to know how many lenses you are passing the image through, depending on the fixture, to know which side needs to be toward the lamp which would also determine which side of the gobo gets coated. This of course would really only be crucial for gobos with text and branding, not so much for a breakup pattern... Just sayin'...
     
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  9. JChenault

    JChenault Well-Known Member

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    The shinier side / more reflective side is the one which has no pigment/dye on the surface. It is facing the lamp / reflector at this time
     
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  10. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    SourceFour 19°, 26°, & 50° have one lenses. SourceFour 36° has two. Gobo with text goes the same way in all.
    Myth busted.
     
    Last edited: Sep 5, 2019
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  11. tdrga

    tdrga Active Member

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    Minor correction: the number of lenses is backwards - 36 degree has 2 lenses, the others listed have one. Does not affect the busting of the myth. :)
    -Todd
     
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  12. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    :doh:


    Corrected. TY.
     
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