PAR, ACL, and PAR Can invention

ship

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Doing some resarch on the subject such as why the #4552 lamp has a parshal filament shield about it, the invention of the lamp, usaage for stage and entertainment etc. and when the individual fixture came to market. Any ideas from PAR lmp invention and when and what size, that of the ACL lamp introduced to theater and nore info about the PAR can?
 

mrb

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the filament shield is the block direct radiation from the filiment and force all emitted light to the reflector to maintain the tight beam and sharp cutoff. Same as in a pinspot lamp.

As far as when it made the transition from airplane to stage, I have no idea but if I were to guess:
a: Sometime in the late 70s
b: it was a british roadie who was on an airfield and thought 'ive got to get some of the lamps off that aircraft into my rig' and
c: alcohol was likely involved.
 

derekleffew

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Extra points for xander! The wiki entry PAR contains the rest, or the prequel to the story: the invention of the PAR can.
...but Bill McManus was a legend in lighting and what concerts have become today. ...
-------------
Bill McManus, Lighting Industry Pioneer- 1946-2005
...
One of the fixtures that Monck had on the Stones tour was the
Cine-PAR, originally built by Kliegel Brothers for the newsreel
industry. Said McManus, “The Cine-PAR was barely a fixture. It had a
yoke that held a very shallow round stamping with two ridges and two
retainer rings; one for PAR 64 lamps and a smaller inner ring for PAR
56 lamps. The back of the lamp stuck out of the fixture and the exposed
lamp prongs were attached to the porcelain socket and wires that ran to
the yoke. 10" by 10" gel frames were held in place by gravity and clips
were spot-welded on the two sides and bottom.”
The fixture was rarely used by anyone in the concert touring industry.
It produced an oval-shaped pool of light, unlike the traditional circle
shape. Because of its short barrel, it burned through gel very quickly.
Monck used it on the Stones tour for backlight with saturated gel for
deep, intense color washes. The Cine-PAR backlight created a vivid
contrast to the white follow spots lighting from the front. The
contrast gave the band depth that was noticed from even the back rows
of the arenas.
...
With the new Jethro Tull budget, McManus approached Altman Lighting
about making a variation of the Cine-PAR. He took a prototype of the
new fixture and met with Ronny Altman. Together they reengineered the
fixture, lengthening the barrel to set the gel further away from the
lamp. The longer barrel had holes for heat dissipation and baffles to
prevent light leaks. They added a spring latch to hold the gel frame in
place and put a rounded cap on the back of the fixture. In the cap,
they cut a hole so a technician could twist the socket to rotate the
beam of the lamp. Within five weeks Altman had built 500 of the
fixtures and the redesigned fixture redefined the lighting industry. ...
The only detail missing is the invention of the lamp itself, which I suspect can be traced to Clarence Birdseye, better known for his frozen foods.

From History of Birds Eye® : Clarence Birdseye : Father of Frozen Food :
He considered this work in whaling as a hobby and during this same period he started a small company (Birdseye Electric Company) to create a single unit bulb and reflector for use in display lighting. He also designed more efficient lighting filaments and heat lamps for use in keeping food warm. In 1939, Birdseye sold the Birdseye Electric Company and it later became a part of the Sylvania Company.
Thus the "R" or reflector lamp, which certainly must have preceded the PAR lamp. The challenge remains for anyone to find information on the first PAR64 lamp.

ship, please let us know what, if anything, your research reveals on Bortz dot.
 
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JD

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Doing some resarch on the subject such as why the #4552 lamp has a parshal filament shield about it, the invention of the lamp, usaage for stage and entertainment etc. and when the individual fixture came to market. Any ideas from PAR lmp invention and when and what size, that of the ACL lamp introduced to theater and nore info about the PAR can?
ACL's actually have an "up" and a "down" when used as an Aircraft Landing Light. The shield cuts side spill in one direction. (Kind of like the old sealed beam car headlights.)
 

ship

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On the PAR 64 rock and roll or theater can it was "Concert Lighting" - Moody 1998, says in his Preface that the PAR 64 fixture came from the film industry. (Must be a history of film lighting book out there somewhere than that answers the question of when such a fixture came out for the film industry. Glowman in his own book "Placing Shadows" might otherwise be a good person to contact.) Chip Monck is credited for having brought them to the industry - not sure how/where. "Colortran, Inc., had been mounting the PAR-64 family of lamps in a unit they called The Cine Queen." goes on about saturated gel... in them not lasting with gel... "Bill McManus had seen the lamps and went to Ronnie Altman at Altman Stage Lighting in New York. McManus gave Altman a sketch and asked him to build 500 with the company’’s stock crinkled finish." - this sketch had the gel frame holder on it & the longer snout. New cans first used on Jethro Tull’’s Passion Play tour in late 1971. Another 500x were sold to Bob See at See-Factor - Altman made more. Jethro Tull and it’’s implied that the Stones apparently were the first tours to use the new gel frame clipped new cans. (No mention of what tour/s Monck was first using them on.) That’s the history amongst 37 books researched and a few websites I found so far on the PAR can fixture.

Ok, so we have established the invention of the Rock and Roll PAR can or at least the more theater PAR 64 steel can perhaps over this above Colortran Cine Queen fixture that didn’t work so well with gel. When did this Cine Queen fixture come out? That’s the PAR 64 as an individual fixture all of this is based upon. Also by than was it 1Kw quartz/halogen or 500w. incandescent in use in either case? When did the 1Kw quartz lamp come out? This much less the Thorn HX-156 at 1.2Kw come out in now being discontunued but survive long enough to get an ANSI code such as a GFA lamp?

Ok, beyond the PAR can, I have this book, "Architectural Lighting Graphics" - Flynn 1962 that lists the 75&150w PAR 38, 200w PAR 46, 300w PAR 56 and 500w PAR 64 lamps in use at that time, amongst a few R-Lamps. It documents the use of all lamps except the PAR 64 as if an “Architectural Graphics Standards” book for the use of all fixtures in architectural lighting fixtures except no mention I might have missed of a PAR 64 application. Might have missed the original use of a PAR 64 500w/120v lamp as presented for many beam spreads, but mostly these PAR lamps have been in use long before their adoption to theater cans or rock cans for the architectural lighting industry.

"The Art of Stage Lighting" - Bentham 1968, (of later use in ACL lamps) "What appealed to these men was the strong beam of light itself rather than the malformed patch at the end of it, and it is interesting to find the Germans getting much the same effect with low-voltage. (Nedervolt) spots after the war. There had been sporadic attempts to take advantage of the greater efficiency and smaller low-voltage filaments here and there in the thirties, but post-war this became a necessity in Germany."
Section about 8mm projector lamps and PAR lamps. "A wide range of beam distribution has been available for some years now in the United States and these are gradually appearing over here. Great efficiency is possible, for each lamp is virtually a complete optical system and when low voltage filaments or tungsten-halogen sources are sealed in the light output is remarkable.
All this must be viewed with caution, however, as far as the theater is concerned, for these are fixed beams. In a narrow-beam spotlight type of sealed beam lamp the optical system is designed for one purpose only. All the efficiency that can be extracted pours out on this one beam distribution;
(photo / fig. 43. Sealed-beam lamps: top left to right: 1-Kw PAR 64 spot, 500-watt PAR 56 spot, and medium flood; bottom: 150-watt PAR 36 spot and flood) {note image shown is a PAR 38 not a PAR 36 - either a typo or there might have been a PAR 36 in use back than, just not these bottle neck medium screw ones shown.}
and what chance do the multi-purpose, variable-beam, jack-of-all-trades stage spotlights stand by comparison? Variable beam control and distribution, and our behest, are essential. Therefore, beware! If hundreds of sealed beam lamps are deployed as general stage lighting, the orthodox spotlighting is going to take a hard knock. Stage lighting does not have to be bright, it has to appear bright and this is not the same thing at all. (Onto the section on Lamp Efficiency and Color Temperature, and I totally agree with his statement - also given in High School I had a teacher that was hoping to replace all of our Century/Strand Lekos with PAR Cans so he wouldn’’t have to deal with maintaining them - this was in the mid-80's. Also further above mention in the Pagent lighting section of Germany’’s liking the narrow spot type lighting as opposed to wash or wider beam spread.)

It would seem by the late 1960's that theaters were using architectural PAR can’s and not the studio grade PAR cans that Bellmen was fighting against the use of below.
"Lighting the Stage: Art and Practice" - Bellman 1967
"There are available a number of makes of lamp holders for Type R lamps that cut down the back spill and provide for the use of color media. The holders usually are combined with a swivel socket to facilitate directing the unit. While most of these lamp holders (fixtures) are quite useful for store-window lighting and various types of decorative lighting, they are not rugged enough to stand the wear and tear of stage use. The swivel sockets soon lose their ability to hold the lamps in position, and the rest of the apparatus becomes bent or dented beyond repair. Thus the holders are usually a poor investment; their cost, plus that of the lamp, is nearly equal to that of a small floodlight or spotlight which would be much more durable and useful. The Type R lamps are also made in a "spot" type that produces..... Reflector lamps are often said to be the "poor man's spotlight."

"In contrast to specific lighting application, there are several good boardlight units available that are designed for Type R lamps. They have the advantage of extremely high efficency. Moreover, their reflector efficiency does not drop with age because the reflectors are renewed with each relamping. Most of them are designed to take either Type R or the more rugged variety, Type PAR lamp. PAR lamps are constructed with a heavy pyrex glass envelope that is capable of taking the stresses that may occur when the hot lamp is doused by rain or a carelessly directed garden hose. The original purpose of these lamps was outdoor architectural lighting. However, their ruggedness makes them more adaptable to stage purposes than the R types. Dangers from breakage are greatly reduced when these lamps are used. There are still drawbacks: PAR lamps weigh more than R lamps, they still get very hot, and their cost is considerably more than R lamps. Light distribution characteristics of PAR lamps are also different, but this is not necessarily a disadvantage because it offers the lighting technician a wider range of choices."

"Both the R and PAR types are available in a wide range of wattages from 75 to as high as 1500 watts in certain cases. Proliferation of types has blurred the distinction between R and PAR to the extent that R-type envelopes may now be obtained of pyrex glass, making them "waterproof." Pyrex does not materially increase their mechanical strength. To take advantage of the high efficiency of large reflector lamps, cyclorama striplights are available that are designed to use R56 or R64 lammps, 300 and 500 watts respectively. (Think he means PAR)
"The stage-lighting artist will find that he must keep up on the latest developments in this series of lamps if he wishes to take advantage of their great efficiency. New types and additional improvements are constantly appearing. (See Appendix III for ordering data.)"


So did Monck see a show lit by Colortran fixtures first, or read a book or do theatrical shows in using architectural fixture usages of such lamps first? All perhaps in a back of the mind in bothering him and McManus in re-designing the fixture for stage/rock usage. Kind of like that advent of the ETC S-4 fixture, perhaps it wasn’t only the 360Q but they took a number of problems with brands or types into account in revolutionizing the industry.

Otherwise, at what point did the industry say stop converting say Halo brand track light fixtures into stage light C-Clamp fixtures for use on stage as seemingly in use and fought against well before before the Rock and Roll Can came to market? Theater’s could not afford Studio lighting such as a Colortran PAR 64 and other PAR fixture thus it could be assumed they didn’t use them. They could afford architectural fixtures though and it would seem they were in use.. This in a less than benevolent way that Bellman asserts without finding a solution for the why they are seemingly in use problem.

That’s the rock and roll or at least Theater PAR 64 Can in concept and a few versions of them in that period.

Still though back to the PAR lamp and ACL lamps themselves. Pattents issued for PAR type reflectors within T-type tube lamps for PAR lamps, and low voltage lighting concepts withing various pattent research before and after the war. Seems like that was the hayday for such lamps and concepts.

Look at a #4552 lamp though. It’s not a filament shied as per say a #4559 or #4515, it’s a hemispheric shield instead that don’t block the output from the filament in other than one direction. Main question of this and a few similar lamps is what’s the purpose of this shield that don’t persay block light out of the filament, instead it blocks light out of it for say 2/3 of the spill light from the lamp.

Thinking such a hemispheric shield if of more use in blocking the light upwards to other planes above or in blocking the light as might be seen by the pilot in looking out his window. That’s perhaps the purpose but I get no help from GE on this question. Not a filament shield, what is that say 1/3 wrap of shield doing inside the lamp on a #4552 and other lamps?

The ACL lamp was not for landing, it was for use in airplanes.

On the other hand the PAR 38 lamp goes back to the late 38's and early 40's as mentioned in books. PAR 56 lamp also in later 40's as a lamp type in use. This assuming for architectural fixtures but also for use as cyc or strip lights. Such lamps are ancient for the most part in development except they were more so just a bank of them until at some point in say the 60's or late 50's when for an architectural use they became adopted at some point for theater use as say a house light. And at that point someone in being creative made their first architectural can for use on stage I think.


Assuming since the early 60's or before, at very least on the PAR 38, someone made an individual fixture for it at some point. Don’t know when the PAR 64 lamp came out before 1962, or when it went halogen say around 1968, but such lamps were in use already perhaps. Than the PAR 56 lamp also much earliar.

All this, when did Mole Richardson come out in theory with the development of the PAR FAY lamp as a concept? Lots of low voltage PAR 36 lamps out there for many applications but the FAY usage is unique and perhaps important in a lamp type not supported by way of other normally low voltage PAR 36 lamps. Was assuming the studio lighting industry say using their four light PAR 36 fixtures first as say series wired low voltage punch light fixtures before this lamp came out? This the invention of the ACL fixture?

Anyway, this amongst other stuff is where I’m at in data. Bellmen for the most part in taking a stance against the use of architectural fixtures for use on stage lighting also supports the concept of why Monck did what he and McManus did in inventing a new fixture so as to solve the problems of the Colortran they had seen in use. Perhaps it was the 1Kw Quartz version able to handle that wattage of lamp that the 500w incandescent versions could not as seen before that in stolen from the theater/architectural industry for use with 500w lamp. Perhaps too dim and dark for what shows were seen but perhaps such players in the PAR can were also aware of what was on the market already also.

ACL lamps for use on stage - guys way back when no less reding a GE catalogue than I, found a lamp they wanted to use and made it happen. Still the main question on a ACL, what about that hemispherical shield as opposed to filament shield? Why one verses the other the gyst of such a question.
 

JD

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With ACL's, they were used in fixtures above the runway and on aircraft as well (thus the odd voltage.) In the runway application, spill to the ground needed to be avoided so as not to interfere with planes already on the ground, thus the shield. (Grew up next to an airport ;) )

As for the PAR64, I believe the industrial (500PAR64) which had a 2000 hour life, as well as all the variants were around long before their use for film / stage lighting and were used for architectural purposes. These PARs were not 3200k, (2850k) so I suspect their use for film and theater (or Rock) came later. I also suspect that early adoption involved color correction, and that when demand became sufficient, manufacturers had enough of a market to bother producing the 3200k line. (FFN etc.) Of course, with the theater line, and the higher temperature, came the shorter 400 hour life as well ;) The fixtures designed for film & stage probably came later, although this may be a "Chicken or the Egg" question.

Somewhere, I have a very old GE lamp catalog (~ 1960) and the industrial PARs are listed, but none of the theatrical versions.
 

SteveB

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I'm also thinking that Mole-Richardson had a single PAR64 fixture, no long snoot (film doesn't use color after all), and introduced this fixture before Colortran. The MR unit I think has been around for decades is the Molequartz MolePar. Reason I think that Altman copied MR as opposed to Colortran, is C-Tran at the time was trying to break in to the film lighting market and copied a number of MR units (open faced, etc..). The MR units were then and still are extraordinarily expensive units for what they do - witness the currentl list on a MolePar at $425, no lamp.

SB
 

gafftapegreenia

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ship

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Anyway, that’s where we are at with research. Thanks all in getting it a bit further.

Never wondered about the PAR can or lamps including the ACL before. I was always more into Fresnel type lamp/fixture development. The PAR 36 lamp at 120v is interesting also in development. Not mentioned in stage lighting books but probably listed in some sort of studio lighting history or various period architectural fixture catalogues. Recommendations on a good studio lighting book that will further give these types of answers? My... I wish I had lamp catalogues older than like 1987ish. Any chance or borrowing it to add lamp by lamp it's data to my tables? Good swag in the trade...

Thinking the “poor man’s spotlight” says a lot about the small theater scene of the late 1960's. What was that era called? This similar to my own early 90's store front theater scene where I again was using architectural fixtures for lighting - just to get some useful light on stage. At some point during the 1960's the theater scene started using architectural lighting fixtures for at least supplemental lighting use in lighting their shows. Such can’s probably were not of high enough wattage for use in the touring industry thus the cinema type lights in use. PAR can history itself, for the most part solved - when the Colortran or Mole product came out or when architectural PAR can’s came out is more or less a detail - somewhere between say the 40's and early 60's. The individual PAR fixture is established as a decently old fixture. Got two 500w rated Strand PAR 64 fixtures, any idea of when they came out?

On lamps, perhaps the 120v line voltage PAR 38 was following the R-lamp first in development for a more rugged version. The PAR 56 next as a lamp that was no longer screw based. By the early 1960's the PAR 46 and 64 were also on the market I think in their incandescent versions.

ACL PAR lamps parallel this I think in from the 40's on they were airport, airplane and car usage. Believe a PAR 56 low voltage lamp is what’s used on a 56' chevy but I don’t know cars. While interesting the odd voltages in use at airports, trains and mines, the various 6v and 12v lamps available make sense. Fascinating T-lamp design from like 1939 that had a reflector inside in doing a pattent research.

Still kind of a black hole about when the PAR 36 (not mentioned in 1962 as a lamp type but no low voltage lamps were listed) and low voltage PAR 64 lamps came out or when some started using them in-series for punch lights in the movie industry or on stage. Thinking that the four light Mole FAY fixture might have been a useful fixture so as to do so, though I’m told that on 28v lamp bars, they used to do five not four lamps and there is no Mole 5-Lite fixtures out there. Perhaps a six light fixture wired in series with one line voltage or not used as a concept in doing the ACL PAR’s. Likely it was a bank of them like with banks of PAR 38 or 56 cyc lights in use long before individual cans came out, and given it took the individual fixture and lamp bar before individual fixtures could be wired for ACL. Thinking unless someone did a custom fixture or custom wiring, that the use of a PAR ACL bar didn’t come out until long after the development of the individual can.

Also thinking I’m correct or JD is correct in that hemispheric shield. The voltage verses the lamp life leaves this as an open question in me thinking more use for in planes that don’t have to have them on as long but equal concept. This assuming a 24v or 28v system in planes as possible.

Still more interested in Fresnels and Lekos’ but say a sub concept for me about development, thanks.
 
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JD

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28v is common plane voltage. When mounted on the plane, shield goes up to block stray light from bouncing off fog, clouds, etc. so that pilot can see. When used on ground towers, goes down to block stray light from interfering with work on the ground etc.

Not sure why 28, as what I have seen looks a awful lot like two car batteries in series. But then again, as the Chilton Manual says, "You should measure 13.5 to 14.2 volts at the terminals of the car's 12 volt battery. Love that book.....
 

ship

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28v is common plane voltage. When mounted on the plane, shield goes up to block stray light from bouncing off fog, clouds, etc. so that pilot can see. When used on ground towers, goes down to block stray light from interfering with work on the ground etc.

Not sure why 28, as what I have seen looks a awful lot like two car batteries in series. But then again, as the Chilton Manual says, "You should measure 13.5 to 14.2 volts at the terminals of the car's 12 volt battery. Love that book.....
Ah' thanks for the info and conformation. Do you mean "Architectural Lighting Graphics"? Yea a great one.

Question now perhaps with the shield to ignore or use in pointing away from something?
 

WooferHound

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It documents the use of all lamps except the PAR 64 as if an “Architectural Graphics Standards” book for the use of all fixtures in architectural lighting fixtures except no mention I might have missed of a PAR 64 application. Might have missed the original use of a PAR 64 500w/120v lamp as presented for many beam spreads, but mostly these PAR lamps have been in use long before their adoption to theater cans or rock cans for the architectural lighting industry.
I have worked at a lighting company here off-and-on for over 30 years. At one time a very knowledgeable person named John Messina was working with us. There was a day that we were discussing lighting fixture design and he was explaining to me that the PAR 64 was originally designed and used for Warehouse Lighting. I have seen them used from back in the 60's for church stage lighting.
 

venuetech

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I would think that PAR lamp development would have a marine history, with a later crossover into automotive / aviation. The salt water environment would take a toll on reflectors so and fixtures the shipping industry and a sealed lamp reflector would prove very cost effective. power of any voltage on a vessel would not be a problem. If you look at the twenty's or thirty's as the development time shipping would be the industry that had the need. Aviation at that time was primarily a daytime event. Even today par fixtures are on-board vessels of all sizes and commonly used to aid navigation.
It would not be the first time an aid to navigation development made its way onto the stage.
 

jonliles

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The PAR traces design back prior to WW2. Tehy can be seen on many vintage airplanes...But,alas, we are necroposting
 

Lotos

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Not sure why 28, as what I have seen looks a awful lot like two car batteries in series. But then again, as the Chilton Manual says, "You should measure 13.5 to 14.2 volts at the terminals of the car's 12 volt battery. Love that book.....
After a trip to the local car parts store for a new battery for my others halfs vehicle, I can explain this.

In order to diagnose why her car was 'sluggish' in starting, and the radio was resetting the clock to 12:00, I called my father... A mechanic of some 25+ years... I suspected the battery, but wanted to make sure I wasn't missing something.
He instructed me to turn the car on, and rev it to 1500rpms, and then measure the voltage output of the Alternator, as to charge the battery properly, it should be outputting ~14v DC... Low and behold, exactly 14v... He suggested that I turn on the AC/Headlights/Everything, and test again... 13.9v.
Alright, he said, the alternator is fine. It's either the starter or the battery, now to take it to a mechanic and have the battery load tested. (As I stated already, thankfully, it was just a battery at the end of its useful life.)

Long story short... When a vehicle is running, the electrics are drawing from the alternator, not the battery... While the battery may be a '12v' battery, the alternator outputs the 14 needed to charge the battery.
 

derekleffew

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Not to make light of (get it? Make light of?) the contributions of Mssrs. Monck, McManus, and Altman, but it appears a little company in Utah was using R and PAR lamps in theatrical fixtures well before any of them, and possibly even prior to the ColorTran CineQueen.

From a catalog dated 1960:
Parliter1.jpg Parliter2.jpg
LIGHTING ARTISTRY with ARIELITE® "par excellence", 1960-1961 Edition, Ariel Davis Manufacturing Company, ©1960.

-----------
Mr. Davis and his successors also used the PAR64 lamp (with less-than-stellar success) as a source for a framing spotlight--see the thread http://www.controlbooth.com/forums/lighting-electrics/5916-electro-controls-3201-3214-ers.html#post190353 . (Ship and I would love to have one of these, if anyone happens to see one just sitting around in a back room somewhere.:))

About the same time, Little Stage Lighting Company of Dallas, Texas also had a profile fixture using the PAR64, called the "Z-Lite." It, too, was a failure in the marketplace. From Catalog 3:
View attachment Little Z-Lite.pdf
Note the price list, dated 01/23/1963, lists the Z6-Y fixture at $47.00. That's MSRP! The Z26-Y, with two 6x9 P.C. lenses instead of a single 6x8 step lens, is $57.00.
 
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ship

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Very interesting, thanks all in continued pooling of the brain trust that's implementation into the theater really isn't that old. Keep it going as fascinating.

Side notes, the modern PAR 64 did come from a ColorTran fixture as used during a show in burning thru gel, - Nook chated with the inventor as mentioned in a PLSN article he wrote a few months ago. Also chatted with the inventor of the SeeFactor PAR 64 ACL, and while the article didn't use the photo of one I sent, it was a 1970-1972 Neal Diamond tour that was the first to use such fixtures as purpose built an in bulk for the modern purpose. Fascinating notes from the interviews. What specific year of tour this fixture was invented for as at the time a totally different fixture is not known. Pattent dates for various ACL lamps go way back to the 20's or 30's.

On the other hand, theater people are inventive and no doubt there was usages of the line voltage and low voltage lamps in use a times before this. I found a few quotes in period books about the use of architectural fixtures for theater lighting - against it, in a more about the fixture than the lamp type in complaint. Wasn't much arguement I remember in readings against the use of a PAR for a proper Fresnel or Leko... that became a later arguement I think once PAR fixtures became cheaper and viable. Forget, was it "Theater of Revolution" the 1960's was named?

What ever the case, even I in the 90's was at times using architectural fixtures to bulk up my inventory. Some curious modifications to PAR 56's, PAR 46's, and even Pinspots to make into PAR 38's. in use. Gel frame brackets to track lighting Halo PAR 46 fixtures, as used for short throw distance, actual coffee cans added to PAR 56 also track light fixtures, and gel frame clips added, and someone before me doing the pinspot to PAR 38 conversion - really badly.

Could never figure out who was hot gluing the PAR 38 lamps to the cans. Difficult enough to get the lamps out of the cans given a single screw mounting the base which often got loose in unscrewing it. Turns out it wasn't hot glue, it was the plastic base itself that was melting down and literally glueing the PAR 38 to the can with the bleed from the plastic bases in use. Did a porcelain cleat type upgrade to them once I figured that out. Still though, difficult to focus, slipped etc, and really not designed for gel, I can understand how architectural fixtures were not recommended for theater use back in the 60's. Plus, over the years more punch was needed or wanted and most architectural fixtures/lamps would not be able to support such a thing.

The 500w PAR 64 wasn't a common architectural lighting fixture, much less the 1Kw version once halogen, would be too much punch. For most architectural lighting purposes the 300 PAR 56 especially in spot version, or various 200 PAR 46 or 150 PAR 38 was fine for architectural purposes. Such architectural lights and lamps mostly wouldn't be sufficient for touring or stage lighting unless short throw. Not a proper theater type of thing this lower wattage short throw but could have been a studio theater type of thing. Also, wouldn't work with concert touring. I think architectural cans were in use but in small theater use and not a concert lighting leading the way or proper theater lighting start to the usage of overall of going studio/movie type gear over architectural gear.