"EE designer in earlier days"... made huge mistakes in my past also - we all learn in doing the best thoughts we had back than. Hopefully those of the
current days in doing new stuff are not of them specifying gear in learning still from our past and
current mistakes.
Base of experience is always a good thing to consider in having already made the mistakes and currently working in the field. This over someone 20 years out of date and without
current and constant projects or just out of school without specific supervision on the project.
Assuming dialing in the flourescents for output and
color temperature isn’t an option - even if a
parameter mount of them in going 120 degree
LED lamps in them might work well in this situation in even dialing in a range of
color temperature. Perhaps the
HPL lamps in general are useful for the situation. Wonder about the specifier in having specified the flourescent tubes about the
stage walls - how much did such a person get paid for doing the
photometrics design on such a contract. I assume the fire wall also works well with something against it in if a typical
proscenium stage amongst other questions. Gee, why has this never been done before of did the specifer even think that far ahead into research into how to do it?
On the plus side of flourescents you can dial in the color temp. and lamp life between like 7,2K and 2,8K dependant on the lamp used for
color temperature.
CRI of the lamp used should also be looked at as often the contractor supplied lamps won’t be as good.
In back to the
HPL lamps... I note it was
HPL 575w/115v and now there is all this talk about jumping to 750w in general. Higher wattage is not a energy saving option even if long life or 120v. Why would one kill of one’s head room for a special or
gobo, or in general save lamps but not electricity? This much less air conditioning loading due to the wasted heat? Is your
stage bright enough now with
HPL 575w/115v lamps? If the case, it once you replace all with long life 575w/115v lamps will seem initially
dimmer but your eyes will adjust. And imagine the head room you have for specials or important punch lights.
Main consideration for me is what’s your
voltage at the
fixture after all the
dimmer trimming done which is a good basic idea? What was it before at the
fixture given the
HPL 575w/115v lamps? Consider the long life 115v lamps a step parallel or equal to the 120v high output versions. Someone else can do the math below in which best. In exchange for lamp life, you loose output and
color temperature some. Dependant on your actual
voltage, one or the other might work best in preserving more
color temperature. Can
play test them also but the math is better in eye fooled.
Concept is to
drop down the entire
stage some in light
level - you won’t notice it if all done, and also
drop your
dimmer trim down by 10%. Walk into a room with a single lamp, it’s bright to an extent. Walk into a room with two lamps it’s just as bright in seeing it a few hours later.
Slight difference between what GE and Osram specify thus both presented:
Voltage and Light Output: The
effect of
voltage on the light output of a lamp is ±1%
voltage over the rated amount stamped on the lamp, gives 3.1/2% more light or Lumens output but decreases the life by 13% and vise a versa.
Do not operate quartz Projection lamps at over 110% of their design
voltage as rupture might occur. GE Projection, Ibid p.13
A 5% change in the
voltage applied to the lamp results in
-Halving or doubling the lamp life
-a 15% change in luminous flux
-an 8% change in
power
-a 3% change in
current
-a 2% change in
color temperature (0.4% change per1%
voltage.)
Osram Technology and Application
Tungsten halogen Low
Voltage Lamps Photo Optics, p21
Goal should be to do the math in what you have for actual
voltage at the
fixture and output now in doing the math verses once you correct at the dimmers for a lower governed
voltage and measure
voltage at the
fixture what will work out best in output for what situation you have. Goal is to keep them 575w and step down a
bit on expected overall
stage intensity of light. Once used to it - you are going back to the world when a EHD type
Leko was fine of course. Don’t worry about it too much because magic in the theater was made back than and can still be made. (Sort of core cause for me - can we make magic with less lumens and
color temperature?) They did it in the past so it should be carefully done in figuring out how to get back there over brighter isn’t better always. Skill and
beam angle over the
grid worth of
PAR 64 cans as an option in the 80's I fought.
Perhaps this next generation needs to go green in balancing illuminance levels possible but not economic in wattage or green, verses what’s really needed for good illuminance levels assuming good design over throwing more light at the subject to
cover a shortfall in design and staging.
