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Lamp Test

Discussion in 'Lighting and Electrics' started by icewolf08, Nov 18, 2008.

  1. icewolf08

    icewolf08 CBMod CB Mods

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    So, my local dealer was sent some of the new Ushio SPH lamps, and wanted me to setup a shootout/comparison with some of the other lamps that these were meant to compete with. So, what i wanted to know is how you all think that I should set up the test. I have the high output and long life versions of the SPH lamp.

    Here is what I have to work with. The test platform would be the old Strand Axials in either a 6x9 or 6x12 or Altman 360Q 6x16s. I also have a couple of Phillips' "The Sink" sitting around so we could put these in ETC source fours for comparison to the HPL. Right now I have been using and have in stock FELs and HX-755s for the Strand units. I know wattage-wise it isn't a direct comparison, but lamp efficiency could make up for that.

    I can probably get a light meter for the shootout, but any other ideas on setup would be great so that I can get you all useful results.
     
  2. maccalder

    maccalder Member

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    Try and get the same fixtures, shine them from a distance of about 2 meters onto a white surface (painted wall) and check for uniformity - make sure you properly line up the lamps and let them "burn in" for an hour before testing, but in general, there should be a slight hot spot in the center with the intensity fairly uniform at all points a given radius from the center.

    If you have a number of fixtures available, check how well they blend with lamps from the same company, and lamps from other companies (ie uniformity of colour temp between lamps and how the colour temp differs between brands).

    If they are in spots, check for focus.

    Finally, leave them on 24hrs a day for 2 or 3 days, check the intensity/colour temperature again.

    It is by no means a definitive test, but it should give some idea as to quality.
     
  3. TimmyP1955

    TimmyP1955 Active Member

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    I think two meters is too close. I'm thinking that the lights would be excessively bright at that distance, decreasing the eye's ability to detect differences in the brightness across the pattern.
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    Hmm... SPH lamps, yet to test them myself, timing and the quote of their specifications something like “some” Ellipsoidals. Test away please, you no doubt will get to it before me.

    What’s the proper bench focus test? 2M seems a bit short, I’m thinking twice that at a white screen at least = what is the bench focus distance for the fixture you are using? For me like 15 to 20 feet is good at a minimum but set distance.

    Initial verses sustained. Ten hours is not enough but should be a start. Not so much worried about that for a filament lamp however - the mortality / output curve of a filament lamp will be less given overall output than that of a moving light lamp I would think. Interesting if you can do it an extend that time to 50% of the lamp life that test / curve but short of that I wouldn’t worry. For a good test you want both light meters in lumens / foot candles, and a light meter that measures color temperature if you want to do it properly. Still for stage usage, if you can see a blackspot or solid beam inside that of another beam when you cross beams that’s also important. Same lenses types how much brighter solid a beam, harder edge and or more even is it?

    This all given very well bench focused beams of light for all fixtures. Also assuming you start with new lamps for all and all are given the same test and attention. Way difference between that of a semi-focused fixture and one that is true in a way that a radial fixture might just seem better than S-4 say.

    “The Sink” lamps in a S-4 fixture are not worth testing. Different and a bit less efficient filament structure and also no longer on the market so not more than educational in study between what lamp is in “the sink” and that of what HPL it’s compared to. That’s a S-4 question and nothing really more that can be studied with such a question. Proper lamp for a S-4 is a HPL and that’s what should be tested with. Same wattage and same voltlage. Same distance and if possible all right next to each other at distance to a white drape at the same beam spread.

    If you cannot match beam spreads, at least lamp to lamp testing should be done with same beam spreads. A 6x9 in comparison to a 6x16 has no value by way of optics comparison for any form of study. Can do either but not both in forming a result in comparison.

    Different school at that point - 2M might be sufficient for a 6x9 test given a manageable beam to measure but wouldn’t be sufficient for a 6x16. On the other hand, a slightly larger distance might be better for both.

    Assuming you have the long life SPH lamp - not seen that yet, will add it to my spec in the morning, than I assume you would compare it with the Phillips sink or not GLA lamp (sink removed). Osram rep says they just re-engineered their own version of the GLA/GLC lamps to be the same as that of the Phillips ones so that’s also a consideration as with the GE/Thorn versions of HX-603/604 I believe they would be beyond ANSI code.

    Once well warm shock testing would also be a concept to check if desiring to base ball bat the fixtures once warm and willing to deal with such a potential problem.

    Unfortunately the HPR lamp is TBA discontinued so other than for academic reasons it’s not worth adding to the test. It’s hoped that some day the GLA/GLC GLD/GLE will have internal reflectors on the other hand.

    Overall loose the FEL’s. Can test them but useless overall. Test the FEL verses a GLA and the GLA for the most part shouldn’t compete other than with gobos for all intensive purposes. This other than in color temperature making up some for that. Test the GLC verses the FEL and perhaps some this also given color temperature. The HX-755 is a GLE lamp by ANSI code for it. That’s also a 750w/115v lamp which should more match up due to it’s long life to a EHG than a FEL for overall output and lamp life. On the other hand with all cases, the FEL lamp is in filament so large in inefficiency pinpoint source of light reflecting, anything is possible. Still better in comparison to a FEL in realistic would be a Philips 750w/115v #6981P lamp or at least a GLD / HX-754.

    Same overall lamp life, different wattage but color temperature in voltage change to make up for that, this plus the #6981P is not for the most part far enough once color temperature is added in, this much less point source of light efficiency is added in no doubt brighter in not much huge difference in output after that.

    Anyway, are you judging the SPH at 575w/115v verses other 575w/115v lamps in something that realistically is going to be seeming to be something like a 800w lamp in comparison to a FEL, or attempting to beat the FEL lamp with a 750w lamp?

    Many paint brushes, center around the 115v types in 575w or 750w but don’t mix and match between the two.

    In setup, you got say a 40 to 60' bar and a white drape or cyc say 15' away.... Place the lights on line and shoulder level and away you go. Stand behind, meter and swing beams of light between beams adjacent to each other. You will get a really good indication. Be fair and scientific and also its given best bench focus’s of course.
     
  5. LightStud

    LightStud Active Member

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    Might I suggest a Variac and VOM so you can verify the proper voltage, as per the manufacturer's specifications, for each lamp?

    Might I also hypothesize that the FEL will be brighter than any other lamp you can find? The geometry of the SPH just seems wrong to me for an axial ellipsoidal reflector spotlight.

    You may also want to read this document: IES LM-73-04. Looking forward to seeing your results.
     
  6. icewolf08

    icewolf08 CBMod CB Mods

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    I won't actually be able to start testing for about a week as we are in the middle of hang and focus for the next show. After that, I will have to round up some other lamps in the 575w category as I don't stock them. Hopefully since my local vendor asked me to conduct the testing they will give me a couple other lamps.
     

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