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Conventional Fixtures PC lanterns

Discussion in 'Lighting and Electrics' started by IlyaSmirnov, Jul 27, 2008.

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Does you own/use PC lanterns?

  1. Yes, use often

    23.5%
  2. Yes, use occasionally

    11.8%
  3. Yes, but will be replacing with other instruments

    0 vote(s)
    0.0%
  4. No

    64.7%
  1. IlyaSmirnov

    IlyaSmirnov Member

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    So, after looking through about a dozen lighting books (mostly college texts) and even more websites, I still can't find a definitive explanation of PC lanterns - everyone has their own term that PC stands for, and the beam has been compared to both Fresnels and ellipsoidals, and it's a relatively uncommon instrument, at least here in the States... Can someone set the record straight?

    What exactly does "PC" stand for? (I've seen plano-convex and "pebble-convex" most) What is the beam and light quality like? How would one compare to a similarly sized Fresnel? Finally, aimed more to those outside the States, how common are they? Would it be worth getting a pair for our school auditorium (if nothing else, to learn about their distinct characteristics), or are they essentially relics from the past, not in common use?

    Thanks in advance, looking forward to learning more about them!
     
  2. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    From the Selecon website: Selecon Lighting - What is a PC?

    I'd say it's basically a fresnel in the sense of the spot <=> flood focus mechanism, but without the trademark fresnel lenses. Here's the fresnel info.

    Selecon website: Selecon Lighting - What is a Fresnel?

    The images showing the lenses are the best way to show the differences between the two.
     
    Last edited: Jul 28, 2008
  3. IlyaSmirnov

    IlyaSmirnov Member

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    So based on that, and also what I've seen elsewhere, a PC essentially has a sharper beam than a Fresnel, and I'm guessing would be a bit brighter, too, at the same wattage, because the lens is a bit more efficient, right? So it sounds as though you could imitate a PC with an out-of-focus ellipsoidal/leko... or would something else in the light quality prevent that?

    Would these differences justify having a couple around, or is this too subtle of a difference to make it worth having both in one's inventory?
     
  4. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    The biggest justification for owning PC's is their wide angle range. Whereas ERS's are often fixed, and zoom ERS's can't zoom over the entire practical range, the PC can. It's a very flexible fixture with a harder edge than a Fresnel, so it's great for specials and front light where shuttering isn't so important. So, beyond that, you are now getting into the debate of fixed ERS vs. zoom ERS. However, a PC is still not an ERS by it's very nature, and thus has characteristics all its own. This might be considered too subtle for the "average" or majority of users, who feel that all you need in this day and age is S4 PARS and ERS's, and while that may work, when a educated designer wants the quality of light found from a PC, only a PC will do. What this really means is for most of us we get along fine with S4 everything, but for those such as Broadway designers, who understand light in a way I can only currently dream of, it matters. I think this is where the real conversation of what constitutes the "art of lighting" begins, and one I don't think I need to explore much further.

    The beam of a PC is indeed sharper than a Fresnel, but softer than an ERS, basically, as you said, an ERS is soft focus.

    The reason you've seen pebble-convex is that modern PC fixtures has a stippling on the back of their lenses, just as Fresnel lenses are stippled. This helps soften the beam, make it smoother, and reduce prismatic affects around the edges of the beam. All of these were considered problems with the older styles of PC's. It was the older style of PC, once so common in the US, that gave PC's a bad name and thus they went the way of the the footlight.

    I wish your poll had one more option: "No, but I'd like a few to play with"

    And one more thing, a Fresnel is not a Step Lens. A Step Lens is a Step Lens.

    [​IMG]
     
    IlyaSmirnov likes this.
  5. waynehoskins

    waynehoskins Active Member

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    Of course, historically the PC came first, and then the Fresnel lens was modified to it, making the Fresnel PC spot.

    I'd like a couple of PCs. I'd like a couple of BPs as well; they're another fixture that's so blasted simple and unique that's also gone the way of the dinosaur.
     
  6. Grog12

    Grog12 CBMod CB Mods Premium Member

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    .....really?

    Can you cite a source?

    Am I just this tired from packing that that sounds wrong?

    maybe i wanted a website too ;)
     
    Last edited: Jul 28, 2008
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    LD Roy Bennett spec'd. about 30 Beam Projectors on Madonna's 2004 tour. Personally, because of the way they were used, I didn't see any reason they couldn't have been PAR64-NSPs.
     
  8. waynehoskins

    waynehoskins Active Member

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    Not readily .. I've read it in old books in years past. The Fresnel lens and step lens are of course ways to make a PC lens take up less glass for a given focal length, and therefore less weight. PC lens came first; PC spot came first. Take a PC spot, change the PC lens for the lightweight Fresnel lens, and you have a Fresnel spot.
     
  9. soundlight

    soundlight Well-Known Member

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  10. waynehoskins

    waynehoskins Active Member

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    I think I actually saw those at USITT '05, and made a point to pick up the brochure. It may have been Selecon, I forget, though the more I think about it I'm more sure it was Wybron.

    Pretty light. Need to get a couple.
     
  11. Grog12

    Grog12 CBMod CB Mods Premium Member

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    Lucky for you I can.... Parker Wolf Scene Design and Stage Lighting 4th ed pg 445.

    Though you leave out one of the most important reason for Fresnel and Step lens: Heat managment. PC lens, do to thickness, were succeptable to cracking.
     
  12. waynehoskins

    waynehoskins Active Member

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    Ah yes, the heat and the cracking. I remember that too. Actually, I remember reading about it.

    I used to have Parker & Wolf 3rd edition, but stupid me loaned it out some years ago and it didn't come back.

    I wonder if any of the ERSes with Fresnel or step lenses were any good? Read about 'em, saw photos, maybe even bumped into a few old ones in college, but never tried any out.
     
  13. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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  14. dramatech

    dramatech Well-Known Member

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    I am old enough, I'm sorry to say, that my high school lighting system consisted of strip lights with roundels for foot lights, cyc lights and the 2nd & 3rd electric. All of the 1st electric (x-ray) and the two FOH positions (beams) were PCs. Yes they did crack with heat.
     
  15. David Ashton

    David Ashton Active Member

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    I'm really surprised that no-one has mentioned the most annoying feature of PC's namely the striation [the filament image] which makes for a very uneven beam, even with the more expensive makes, the pebbling helps a bit but I use fresnels in preference for washes and profiles for distinct areas.
     
  16. TimMiller

    TimMiller Well-Known Member

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    The highend studio beams use a PC lens. Since the thing stays very cool cracking is not an issue. Light beats the crap out of the studio color also.
     
  17. IlyaSmirnov

    IlyaSmirnov Member

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    Thanks for the clarifications, all - I'll try to convince our TD to get a pair of PCs next time we're getting new lights so we can play with them a bit, learn about how best to use them....

    Does anyone have any experience with the Selecon models? They look pretty well built....
     
  18. mbandgeek

    mbandgeek Active Member

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    The local theater I work in uses the Acclaim line of Fresnels. If they are anything like the 4" Fresnels, They will be great very versatile fixtures.
     
  19. philcollins

    philcollins Member

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    The Selecon PC Pro and Fresnel Pro models work very well. I just finished a re-focus job at a church where they had an inventory of Selecon fixtures : PC's, Fresnels, Acclaims, Pacifics, Ramas, etc... it was the first opportunity I had to work with the Selecon product line.
    Good stuff.
     

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