Film-Tech Forum ARCHIVE: Carbon Vs Xenon

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Posted by Adam Fraser (Member # 1074) on 02-08-2002, 10:07 PM:

Just a hypothetical question... I am too young to have delt with a carbon arc projection booth ( I havent even seen one in person) and have always run and seen movies with Xenon lamps. How comparable is the quality of light that is porjected on the screen if both are properly maintained and manned by skilled projectionists?

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Adam Fraser
www.pinestheatre.com

Posted by Gordon McLeod (Member # 33) on 02-08-2002, 10:10 PM:

Carbon is a smoother less harsh light
It measures almost the same in colour temp but is a contious spectrum unlike a discharge lamp that is very closely grouped lines approximating a continous spectrum ( almost like the way digital recreates analogue sound)

Posted by Ken Layton (Member # 133) on 02-08-2002, 10:20 PM:

Hands down---carbon arc is the winner all the way!

Posted by Joe Redifer (Member # 3) on 02-08-2002, 10:29 PM:

Xenon makes carbon look like a faded yellow flickering flourescent bulb! People only like carbon because it reminds them of the old days before electricity! Carbon would cause lung cancer even if you only worked with it for two hours on one day of your life! Xenon ruulllzzzor!!!!!!

Of course I am just saying that to piss off the cabon-o-philes! I have never seen carbon in action.

Posted by Joe Beres (Member # 678) on 02-08-2002, 10:32 PM:

I have only seen poorly run carbon shows, but I must say I love the look it gives on screen. Most recently, I saw Mulholland Drive run with carbon lamphouses, and when the projectionist wasn't losing the arc, the image looked fantastic. Of couse he was working on poorly maintained projectors from 1939! It wasn't all his fault.

Posted by Paul Cassidy (Member # 951) on 02-08-2002, 10:45 PM:

Carbon Arc is mainly what I have used and when set up correctly has a very natural look to it , it can flicker (too much air movement ,cheap carbons or poorly stored,magnet etc.) and you need to keep an eye on them if the feed mech.is wandering other wise they will crash into each other ,they can be expensive e.g the amount used compared to Xenon life (in NZ that is) and hard to get a good supply , you need to have the correct size also for the conditions.

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A KIWI eats,roots & Leaves.

Posted by Jonathan M. Crist (Member # 413) on 02-08-2002, 10:59 PM:

High intensity carbon arcs are usually better for Drive Ins. For some reason Xenon always has a dull flat look when projected on a metal screen.

Posted by Mark Gulbrandsen (Member # 72) on 02-08-2002, 11:20 PM:

Well, Joe has definately not seen the light out of an Ashcraft Super Cinex, thats for sure, its before his time, not quite before electricity though, and quite thankfully was in my time. While I could hardly consider myself a carbon-o-phile, I can claim to having run these just for fun on several occasions for 4th of July outdoor screenings we used to do on Henry's farm west of Sycamore, IL. Steve K. will attest to the fact that its probably about the best light he's ever seen too. Really an amazing lamphouse! If you ahve not seen 70mm projected with one of these lamphouses then you've never seen 70mm's capabilities.
Mark @ GTS

Posted by John Walsh (Member # 168) on 02-08-2002, 11:33 PM:

IMHO, I think Ashcraft carbon lamps were the best quality arc lamps ever. Good even light, reliable, well made, easily cleaned and serviced.

The light did look better, but they were a lot of work to operate. We talked about this in an earlier topic. A multiplex could never afford the expense of using carbons today.

Another example of things that really were better years ago.

Posted by Bill Enos (Member # 440) on 02-09-2002, 12:30 AM:

Fifteen years ago when I started I would say carbons were a better looking source, but today there are no decent carbons. We replace our arc lamps in October because the quality of ALL the carbons we could get was terrible, nothing but very yellow and dim from the Nationals, it was as though there was no core. Marble Double Eagles had fair light but they flickered constantly. The Nationals also burned inconsistently, sometimes you could watch a quarter to half inch of carbon disappear in a couple minutes, normal would be 5 to 8 minutes.The lamps & rectifiers are in good working condition. Last August when I inquired at National about continued availability if 8mm positives I was told they have none and didn't know when or IF there would ever be anymore. Marble's supply seems to be spotty at best. The xenons seem to produce more light and just as good light for a hell of a lot less money and without the aggravation, dust, ash, and smoke. Throw the damned carbon arcs in the dumpster where they should have been 10 years ago.

Posted by Stan Gunn (Member # 554) on 02-09-2002, 12:36 AM:

I still use carbons!
Ãnd a friend of mine still uses carbon in his cinema!
In my case I use them in my home cinema for both 35mm and 16mm
the 16mm being a pair of GAUMONT BELL&HOWELL 609s with KALEE universal carbon lamps.
16mm at 80foot 6foot high screen. Had to have the screen water cooled, and give the patrons sun glasses.

Carbon per watt of light would be the same as xenon, carbons obtained at the right price is about the same cost as running a xenon to is usefull life.
PS
anyone got any info on the B&H GAUMONT setup I have no info at all thanks in anticapation.

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KALEE FOREVER.
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.

Posted by Paul Harnden (Member # 1034) on 02-09-2002, 12:38 AM:

Just want to pop in and say great thread Adam.
I too have only worked with Xenon. But it's also nice to know and learn about Carbon Arcs and there pros/cons. Keep up the great work guys!!

Posted by Paul G. Thompson (Member # 655) on 02-09-2002, 12:50 AM:

OK, when I was with MTS, I was told never to demonstrate a Xenon against a carbon-arc. Especially the Peerless Magnarc. The Peerless with flat out-do it.

The Ashcan that was spoken of was a very good lamp. I had Ashcans at the old Circus Drive-in, and BX-60 heads. I ran some RCA Wide-Arc's at the Skagit Drive in using 11 mm rotating positive carbons behind Super Simplex heads.

While in training with MTS, a Star-Wars movie was run in a 70mm house in Minneapolis, and the lamps were Ashcans using 13.6mm rotating positive carbon. The projectionist was a union person, and he worked his equipment to the max. The end result was one of the most perfect presentations I have ever seen, and it was done manually. The light and picture quality (along with the sound) blew me away.

Carbon Arcs rule!!!!

Posted by Frank Angel (Member # 248) on 02-09-2002, 01:26 AM:

Carbons flicker? Oh, and like xenon never flickers, does it! Carbons more expensive $$/per watt a tad, but that's only until the first xenon bulb blows up and takes the mirror and half the electronics with it. You've gotta burn a LOT of carbons to make up for a blown bulb, to say nothing if someone wasn't handling it correctly while changing it. The damn things just want to explode by their very nature. The only thing can happen if you drop a box of carbons is a few might snap.

As we say in Brooklyn, not for nuthin, but it's a lot easier to go into the accountant's office and say I need $300 to buy some carbons, than it is to go in and say, I need $1400 to buy a new bulb. That's why lots of xenons are burned way past their rated life.

And as far as getting lousy light from a Peerless or especially an Ashcraft (or as Paul likes to call them, Ashcans), then something is way out of wack. Carbon light is SMOOTH....edge-to-edge and there is just something about it that the eye loves. Hey, they those carbon arc lamphouses were good enough to light some of the great classics in 70mm -- time hasn't somehow changed the technology. I use Marble carbons and they burn very evenly and with barely a touchup during a reel. If your feed is all over the place, then it's adjustment time. Only time we have trouble is when the power utility drops or kicks up voltage.

Yeah, they are more work than xenon, but that's what you're in the booth for. And remember, from the first time you strike a brand new xenon bulb, it begins to deteriorate. You can't tweak it, cept maybe rotating the bulb once in a thousand hours. Carbon arc light can be tweaked on the fly and you can adjust the lamp so as to always give perfect light. Not much you can do for a xenon when that big black soot coating darkens half your xenon bulb.

See the light....it's carbon arc.

Posted by Frank Rapisardi (Member # 435) on 02-09-2002, 05:47 AM:

I always liked carbon.But I usually worked in change over(Reel to Reel)houses and drive-ins.Some work;changing carbons etc but all in all I think the picture is much better.Especially on a huge drive-in screen.

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Posted by Scott Norwood (Member # 30) on 02-09-2002, 07:24 AM:

I vote for carbon, with respect to the quality of the light. Assuming that the carbons and the operator are good, there is barely any visible flicker, and the improved color quality more than makes up for that. It also avoids the problem of xenon color shifts over time; I _hate_ watching film in a changeover house with xenon where the bulbs have aged differently and the color temperature changes with every reel (even for B&W films!).

I enjoy running carbons, but I wouldn't want to do it 8 hours a day for years, either.

Posted by John Anastasio (Member # 607) on 02-09-2002, 10:23 AM:

I'm with you, Scott. There's no light as beautifully white as carbon light, but I don't think I could deal with the mess and fuss of running them all the time. Xenon is the "flourescent light" of projection. It's harsher....but oh, so convenient.

Posted by Paul Mayer (Member # 355) on 02-09-2002, 02:24 PM:

For followspots (hey, they're projection, sorta

) I still miss the look of the carbon arc version of Strong's Short-Throw Super Trouper. As others have stated, carbon gave a very smooth look, spectrum-wise and field uniformity-wise. For some reason today's Xenon Super Troupers still don't have the "punch" of the old carbons. When they first came out, the Strong Xenons had horrible field uniformity--no adjustment of reflector or bulb would give you an evenly lit field. I guess it had something to do with Xenon having a much smaller gas ball than carbon, necessitating a much deeper reflector, and being much less forgiving of small manufacturing defects in the figure of said reflector. Today's Xenons are much improved in that regard.

The feel of the new lamps is very different too. The old lamps were heavier, but smoother to operate and better balanced. The present lamps are lighter, but feel cheaper IMNSHO. Oops, my motion detectors have picked up the OT Police crossing the perimeter. Later!

Paul
Underemployed mercenary film/video projectionist/engineer
"Otaku wa tsurai yo" <-- Yeah I know, bad Japanese pun. Sue me.
It's tough being a fan!

Posted by Gordon Bachlund (Member # 124) on 02-09-2002, 06:19 PM:

Here's a thread I HAVE to jump into.

Carbon arc lamphouses require additional effort on the part of the projectionist, but if that effort is expended, the quality of the light is outstanding and consistent. The qualified projectionists who used or still use carbon arc lamphouses spend the time to tune up the feed motors and care for the lamphouses, taking justifiable pride in their work. As Frank pointed out, there is no risk of lamp explosions. As far as cost to operate, my analysis favors Xenon only slightly.

I guess it boils down to profit. Xenon filled the bill when multiple screens became the rage and unattended (or at least minimally attended) booths became the operating norm, abetted by automation systems, but all at the expense of the art of showmanship.

Gone are the days when first run houses employed two (or more)licensed union projectionists, and those of us who worked in second run establishments ached to earn such seniority and skills as would enable us to climb the ladder to such prestige venues.

Call me a curmudgeon, but I'm with Ken and Frank on this one!

Posted by Tom Fermanian (Member # 1094) on 02-09-2002, 06:38 PM:

Having been trained and brought up with carbon arcs (Peerless Magnarcs) My vote goes for best light /colours/ brightness CARBONS
Alas in todays multiplex theatres Xenon wins for the practical aspect, and a close sewcond for brightness etc. BUT if I had to run run a single screen house, I would prefer carbons.

Tom Fermanian

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Posted by Adam Fraser (Member # 1074) on 02-10-2002, 12:39 AM:

Hey guys, thanks for all the info... Its kind of a weird for me to say it but I have been raised and trained on peerless magnarc's too, just witha kniesley 2000 Watt xenon conversion. I will look foreward to seeing carbons in action.....

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Adam Fraser
www.pinestheatre.com

Posted by Robert Golding (Member # 746) on 02-10-2002, 02:51 AM:

I had the pleasure of running carbon arc's for over 20 yrs and there is no comparison between carbon and xenon. It was a work of love to run a Carbon Arc house, they tend to be messy and you must watch them very closly to keep them aligned properly. I've run indoors and outdoors this way, and must say the bigger (13.6's) ones have to be watch as they will change from hour to hour. If you started a movie at the outdoor with clear weather and then it goes rainy, you guess it, the carbon's would feed totally different. The only thing I can say about xenon's is they sure are easier to take care of. If you keep the optic's and bulb clean and they seem to take care of themselves. Also a carbon adjusted properly will give you a light source that has truer color than a xenon ever will.

Posted by Bernie Anderson Jr (Member # 410) on 02-10-2002, 10:24 PM:

If any of you in the New York area want to see Carbon Arcs work, we're running a weekend of shows at the Loew's Jersey in Jersey City NJ at the end of Feb. Check out the website for details: www.loewsjersey.org. Ashcraft Super Corelites at a 160-170 amps are quite impressive.

Posted by Mark Gulbrandsen (Member # 72) on 02-10-2002, 10:34 PM:

bernie, we need to et up a fund to get Joe an airline ticket so he can come see the Corelites in action. He'd be blown away and any xenon he looks at in the future would only make him disgusted!
Mark @ GTS

Posted by Rick Long (Member # 213) on 02-10-2002, 11:19 PM:

There is no doubt that carbon arc gave only what can be described as a "more exciting" light to the projected picture, despite what the specs claim.

My favourite of all time was the Peerless Magnarc type G (great styling) (although the F had much heftier DC connection blocks). The Model J was nice, but without those yellow "marlbled" plastic knobs, it somehow just wasn't a Peerless.

Am I the only one here who actually preferred the Strong 135 (or Mighty 90's) to the Ashcraft? (11MM X 3/8" trim). These used a bi-metal tube upon which the positive crater was focused, via mirrors, to keep the arc where it should be. My experience with these was such that once you lit and stabilized the arc, you could forget it and go make up film without having to worry about it.

It is interesting to wonder with the enviromental legislation of today, whether carbon arcs would ever be allowed to be used anymore.

The carbon arc was indeed, part of the lost magic of being a projectionist.

Posted by Steve Guttag (Member # 268) on 02-10-2002, 11:37 PM:

I ran a set of Futura IIs for the longest time (11mm pos 9mm neg). I always had great success with them. Most operators though complained of flame-outs. They were tempermental about their draft.

As to the debate on Carbon vs Xenon...in terms of light, there is really no debate, carbon has a much better spectrum and is truer to "daylight".

In fact, the industry is now looking to change the standard from the tried and true 5400K to something much higher (as much as 6500K since with Xenon it is really impossible to obtain a true 5400K (looking at all three colors, in order to obtain a 5400K you end up shifting the color spectrum outa whack, something has to give when you try and make a light source perform out of it's native range...kinda like a red reader on an infrared solar cell...but that is another story!).

I would tend to put the Peerless Magnarc at the top of the Carbon heap as the tried and true Carbon Arc lamphouse...sure it wasn't the biggest but it sure did a nice job for it's decades of service.

While it may be true that dropping a box of carbons won't cause an explosion, the damage may just as well be. It can often lead to sputtering.

My favorite carbon arc oddity was running the aforementioned Futuras with 11mm UCARS....I had one of the positives that was slightly under 11mm for most of it's length. All of the sudden, it turned about once for every 10 revolutions of the postive drive! I spent the rest of the reel hand spinning that one!

Steve

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"Old projectionists never die, they just changeover!"

Posted by Steve Kraus (Member # 476) on 02-10-2002, 11:59 PM:

My arc lamp story also involves Futura's (can't remember if I or II).
Perhaps I've already told this story.

Some non-film folks re-opened a single screen 1960's theatre and had not a clue about booth work. Someone suggested they call me. I explained to them the realities of xenon, platter, and automation and took them to a house so equipped and they agreed that that was the way to go. However they were opening within a week and I put them in touch with Mark G. to round up some gear, some new, some used. In the meantime, while holding down a full time job at a post production center I ran this booth, every show for about 6 weeks until the equipment change was made. We had XL's and hour reels.

One weekend a phenolic gear on the negative feed of one lamp broke. As we were running hour reels anyone else in their right mind would have simply added an intermission strip and stuck with the good machine for the few days it took to get a gear sent out. As I am not in my right mind I had a better way. Negative feed is hardly as critical as positive so the bad lamp would run satisfactorily for 5 minutes or so. So I peeled several hundred feet off the 2nd big reel, added leaders and cue marks and made a little mini reel. I'd run the 1st hour, change to the mini reel, then in just a few minutes, rethread the balance of the 2nd hour, retrim the good lamp and change back over. There was just enough time to accomplish this and I knew every word of dialog in that segment and where I needed to be in my proceedings to be on time. I never missed the change though. A couple days later I had my new gear and it was back to normal. A few weeks later the platter and xenon were put in (on the other machine) and the Futura's were retired (although the one in question stuck around as a backup for years).

Posted by John Pytlak (Member # 331) on 02-11-2002, 09:49 AM:

Some links:
http://www.misty.com/people/don/shortarc.html
http://www.uvlamp.com/TechArt/shortarc.htm
http://www.osram.com/service_corner/download_center/photo.html#XBO

Also, check out the "National Projector Carbon Bulletins" in the Film-Tech "Manuals" section.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 585-477-5325 Cell: 716-781-4036 Fax: 585-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Gordon McLeod (Member # 33) on 02-11-2002, 10:19 AM:

My favorite of the big lamps was the futuraII burning 1.6 joinable carbons
The only problem I ever had was once forgetting to trim it
In the smaller lamps I always like the ashcraft C70 better than the peerless

Posted by Steve Kraus (Member # 476) on 02-11-2002, 11:44 AM:

Perhaps I am forgeting but IIRC I was able to get two hours on both positives and negatives but the only problem was that while the positives were fed by knurled rollers the negative feed was via screw whose range was good for little more than an hour. So with the feed cranked all the way down a new rod would need to be clamped about half way up. Next re-trim you'd crank it all the way back and clamp it at the end. It would have been a cool retrofit to create a longer feed screw and have a two hour lamp. Any carbon arc and platter (or giant reel) setups out there?

Posted by Bill Enos (Member # 440) on 02-12-2002, 12:19 AM:

Carbons would be great IF you could get them reliably, but you can't. All you guys are remembering the past. Maybe somebody should buy the production equipment from Morgan Specialty Graphite (the mfgr. of Nationals) and start making them again. If you do, we'll put the Magnarcs back and buy from you.

Posted by Laurence Hammett (Member # 1134) on 02-12-2002, 11:15 AM:

I service 2 booths with carbons. One is a private residence in Belair - two Brenkert's
The other is Landmark's Ken in San Diego - Peerless. I am surprized to see so much traffic on this. I ran Carbons from 1972 until the theatres took them out.
The light is as good as the operator, equipment and media. I managed to get out of the booth on a daily basis but I was glad for Zenons if only for the consistency of an in-warranty bulb.

------------------
Laurence Hammett
Theatre Sound & Projection
Field Service Technician
4806 Fountain Avenue #48
Los Angeles, California 90029
projection35@earthlink.net e-mail
323-377-0882 Cell
323-660-0801 Home
425-984-9815 Fax

Posted by Wes Hughes (Member # 981) on 02-12-2002, 06:37 PM:

Bill: Have you guys already taken the magnarcs out of the byrd, or are you just planning on it very soon???

Posted by John T. Hendrickson, Jr (Member # 849) on 02-12-2002, 08:19 PM:

I ran both Ashcraft Super Cinex and Peerless Magnarcs back in the early 70's. Both were reliable and put out fantastic light. If the feed motors were working properly all you needed was an occasional trim. The water circulators could be a concern with the Ashcrafts. A malfunction would bring a quick end to those silver jaws, but I never had a problem. The light was superior to Xenon.

I do agree that it's tough to get good quality carbons today and that they are obviously impractical for multiple screen locations. Still have nightmares about forgetting to check the carbons before a changeover, even though I was fortunate never to have made that particular mistake.

Posted by Mark Gulbrandsen (Member # 72) on 03-28-2004, 03:05 PM:

"However they were opening within a week and I put them in touch with Mark G. to round up some gear, some new, some used. In the meantime, while holding down a full time job at a post production center I ran this booth, every show for about 6 weeks until the equipment change was made. We had XL's and hour reels."
_________________________________________________________________

Yea I remember that place. They had Futura 1's that were poorly maintained over their life... typical of the poor equipment condition that was found in Chicago booths back then. It was a 1965 installation as thats when the place opened. The Strong rectifiers there were 440 volt and I don't remember where we picked up the 3 phase 208 for the replacement unit, but it was someplace nearby. The other odd thing I remember about this place was that after installing the used Xenex 1 we had about double the light on the screen that the Futura would put out. Could this have been the predecessor installation to Technalite?

I agree with John H. about the Ashcrafts. They were by far the best arcs ever made and the light output was very even and quite unbelievable. 98% of the downtown Chicago booths were Ashcraft equipped and had either Super Cinex's or just plain ole Cinex's. I wish I could latch onto a pair of them to preserve in operating condition. I remember that Lee Artoe had a brand new unused Cinex sitting upstairs at his place the last time I was there back in the early 90's. I wish I had grabbed it!
Mark

Posted by Steve Kraus (Member # 476) on 03-28-2004, 03:18 PM:

I don't think it was doubled but I do recall having the opinion that the Futuras were not putting out what they should have. It's annoying when something doesn't put out, ya know? [Razz]

I believe the utility's transformer supplied 480 or perhaps 277/480 (I vaguely recall the 440 warning sticker but I think it was wrong) and the theatre's own inside dry tranformers supplying the 120/208 so you got that right off the booth main panel.

Posted by John T. Hendrickson, Jr (Member # 849) on 03-28-2004, 08:13 PM:

Well, speaking of carbon arcs, The Peerless Magnarcs will be fired up at the Count Basie Theatre in Red Bank NJ on April 12th. Yours truly will be showing a sneak preview of New Lines Pictures "Laws of Attraction" at 8PM. This is a private showing for patrons and subscribers of the Basie.

I hope to see a couple of local Film Techers on that date. If anyone will be in the area, email me and I'll send you information on getting you up to the booth for the show. We can party between changeovers. [beer]

Posted by Phil Blake (Member # 2012) on 03-28-2004, 11:17 PM:

I learnt my trade on carbons , and more recently moved to xenons.

Although xenons are far more user friendly , I still believe the carbon delivered a much "warmer" image to the screen.

We used BTH suprexs at 180 amps these struggled to light our 100' wide drive in screen , later we changed to Ashcrafts , and I will agree they did a far better job and behaved better than BTH.

Damp rods and cracked mirrors were our main problems (180 amps generated alot of heat).

I have some nice pics of carbon lamphouses in my site www.westnet.com.au/dakota

Posted by William Hooper (Member # 71) on 03-29-2004, 02:17 AM:

I can see the color difference since prints were re-timed for xenon as opposed to carbon, but I suppose that to an audience the difference is as unnoticeable as tungsten lighting vs. sunlight. On black & white prints & earlier color prints, carbon light really looks best.

Operationally, day-to-day use makes xenon more logical, but at venues which run films on an irregular basis, carbon arc is the best. If I go in & it's been several months since the venue ran films, it seems I'm always futzing with & worrying about xenons which have gotten cranky somewhere from humidity or just disuse. With carbons, I just check out, sling 'em in, & go.

I think for those venues, carbons also make more economic sense for new installs. $2G-ish each for bulbs at startup, should have a spare, too, as opposed to $300 for carbons that will last a year or more.

Posted by Leo Enticknap (Member # 534) on 03-29-2004, 03:16 AM:

quote:
If I go in & it's been several months since the venue ran films, it seems I'm always futzing with & worrying about xenons which have gotten cranky somewhere from humidity or just disuse.

Interesting... Darren had a xenon blow up under exactly those circumstances. The theatre had been closed for almost three weeks due to flooding in the basement, so as you can imagine, the whole place was a tad damp. The lamp was struck for the first time on the day we reopened, to rehearse a print; and three to four minutes later... BANG!

The lamp would have gone anyway - after yet another one blew up we discovered that the lamphouse had an incorrect rating of ammeter on it and that we were inadvertantly running the bulbs at around 130 amps. But I did wonder if the coldness and humidity in the box had something to do with that explosion.

Posted by Jim Spohn (Member # 1547) on 03-29-2004, 10:20 AM:

At the Granada, we are a specialty house and specifically installed Ashcraft Carbon-arc lamps because the light is superior. I have a pair of Strong Super-Lumex zenon lamps in the basement just incase we can no longer get carbons. Until then our light of choice is from carbon-arc. ... Jim

Posted by Robert E. Allen (Member # 1351) on 03-29-2004, 12:23 PM:

I'm not sure you'll ever convince the new kids that carbons will outdo xenon lamps. But the one thing I have noticed is that just about every xenon house I have visited is underlit. In fact, it has become such a problem that Boxoffice did a two page article on it this month.

As far as carbons flickering goes they flicker only if you have the damper in your exhaust system improperly adjusted. I used to run with a perfectly steady flame. (Of course they were National carbons. I've heard stories today about other brands spitting and sputtering.)

I'm with the "carbons rule" crowd.

Posted by Stephen Furley (Member # 1277) on 03-29-2004, 12:53 PM:

Anybody remember the dreadful BTH three electrode vertical xenons? In those days there was no contest, carbon was far better. There's no doubt that xenons have improved vastly over the years, the modern ones can be very good

I still like carbon, but there's nowhere still running it in this part of the world now. I could always tell when a cinema had converted, as soon as the curtains opened; it's a different light. It will be a sad day when the last arc goes out for the last time.

Posted by Scott Norwood (Member # 30) on 03-29-2004, 01:01 PM:

Bob--you should check out some of the newer installations (or upgrades) in your area. Not the super-jumbo screens (which, I agree, are usually underlit), but the more reasonable sizes. Most of the newer installations (and older ones done by people who cared) can easily get 16fl. The underlit xenon screens are usually in older mall-type shoebox theatres which had inadequate equipment to begin with or the super-hyper-mega-Xtreme-monster screens that every new multiplex seems to have one or two of.

I usually run carbon once a month or so and occasionally have flicker issues; I'm not sure if it's a mis-set exhaust damper, the carbons (we use Marble's 8mm and 7mm), or the rectifiers. It's not offensively bad and, strangely, it seems to come and go. The light will be perfect one minute and slightly flicker the next.

Posted by Leo Enticknap (Member # 534) on 03-29-2004, 01:09 PM:

quote:
I still like carbon, but there's nowhere still running it in this part of the world now.

The only venue I know of in Britain which still runs carbons is the Tyneside Cinema in Newcastle.

Posted by Robert E. Allen (Member # 1351) on 03-29-2004, 11:49 PM:

Thanks for the tip Scott. The next time I get out of my rural area I'll look for some of the newer installations.

Posted by Warren Smyth (Member # 1838) on 03-30-2004, 04:11 AM:

quote:
occasionally have flicker issue

The quality of Marble carbons used to be variable. Naturally all carbons have to be kept dry and we used to store packets on top of the warm valve racks, I still do in fact at home. I now use National and Loraine which are fine.

Placing a few in the lamphouse (near the side door), provides quick access and helps to dry them out before they are used. Cycling carbons through in this way, reduces the possibility of flickering due to dampness. This isn't so helpful though if you are only screening intermittently.

Interesting to hear complaints about low light level on some screens from xenons these days. I've seen some situations where the film looks as if it's been shot day for night, except for the hot spot at the centre. Carbons arcs may not have been perfect but I used to get brilliant results from 9mm and 10mm as well as 13.6mm rotating trims. 70mm really sparkled and was a real treat. It made all the cleaning and maintanence of arcs worth while although sadly, I appreciate the impracticality of them today.

Posted by Mattias Ohlson (Member # 1662) on 03-31-2004, 04:00 PM:

A newbee qustion.
1 What is the life expectancy range for a medium power xenon bulb?
2 What is the time carbon lighting lasts?

Posted by Leo Enticknap (Member # 534) on 03-31-2004, 04:10 PM:

A typical 2kw xenon bulb (for example) is guaranteed by its manufacturer for 1,500 hours of operation. The guarantee is significant, because a bulb costs US$300 plus to buy new. In reality, many projectionists apply tricks of the trade to make their lamps run an awful lot longer. In the last cinema job I had before moving to archives, I routinely expected to get double the guaranteed hours (i.e. around 3,000) out of each lamp before it started to flicker and needed replacing. The act of striking a xenon lamp is said to take 30 or 60 minutes out of its nominal service life (depending on who you listen to), but once lit and assuming your lamphouse ventilation is OK, it doesn't matter if you then run it for one hour or 1,499.

To be honest, I really don't know what a carbon rod costs to buy off the shelf. The rods burn at a given pace and are of a finite length with a maximum limit, a bit like a candle. The important thing is that there are no rods long enough to run a complete feature through one lamphouse, and therefore a carbon arc installation has to be a two projector/changeover setup. When he gave me a tour of the box a couple of years ago, a projectionist at the Tyneside Cinema in Newcastle told me that he could comfortably get 35-40 minutes out of a rod, thereby enabling him to 'double up' reels onto 4,000 foot spools for projection; but that was the limit. So however good the light quality is, you'd never be able to run carbon arcs in a typical multiplex situation.

Posted by Bill Enos (Member # 440) on 04-01-2004, 12:26 AM:

For me, one $668. 3000 watt zenon replaces around $3000 worth of carbons and produce steadier more reliable light without the carcinogenic dust left by carbons. The carbon arc follow spot is now gone too and the booth is cleaner for it.

For what is worth, a couple years ago I spoke with a man who ran a single screen (I don't remember where) with a platter and carbon arc, he just pulled the switch, adjusted or replaced the trim and restruck while the film ran. It can be done in about ten seconds.

Posted by Steve Kraus (Member # 476) on 04-01-2004, 07:31 AM:

As previously mentioned the Futura lamp could get 2+ hrs out of one pair carbons (depending on current of course) but the negative mechanism (screw drive) was only good for about an hour, clamping the new carbon about half way down, then later you'd crank it back down and reclamp by the end. (Positive was continuous via knurled rollers so no problem there.) It would not be that difficult for some ingenious individual, good with metalworking & mechanics, to rework the negative feed with a longer screw to get 2 hrs worth of travel. Then you could definitely do carbon arc & platter.

Posted by John Pytlak (Member # 331) on 04-01-2004, 08:09 AM:

When I worked at the Grandview Drive-In, we burned National 11mm x 20 inch (L0109) rotating positives in Ashcraft lamphouses at about 120 amperes. One rod would typically be sufficient for three full 2000-foot reels, somewhere close to 5 inches per reel.

Short stubs were used up for showing short reels or cartoons. You definitely never wanted to "cut it too tight" on the positive, lest you flame out or damage the water-cooled silver jaws.

Likewise, the 3/8 x 9 inch National "Orotip" copper coated negative (L1124) would be good for about three reels (about 2 inches per reel).

Posted by Jim Spohn (Member # 1547) on 04-01-2004, 09:09 AM:

We run 60 amps on 11mm X 20" rotating positives and it it burns at the rate of 10 minutes per inch. The shortest we can burn down to is about 3".

Posted by Scott Norwood (Member # 30) on 04-01-2004, 09:15 AM:

At the Avon, we burn 8mm positives and 7mm negatives at about 65 amps in Enarc lamphouses.

A 20-minute reel will burn about 4 1/2 inches of positive and 1 1/2 inches of negative. Since we use 9" negatives and 14" positives, we get about three reels per positive and six per negative. Obviously, this varies, since not all reels are full. I forget what the feed rate is at the Cape Cinema (haven't worked there in a few years), but it's similar.

Enarc lamps could probably burn about 40 minutes continuously before needing to re-clamp the carbons.

Posted by Demetris Thoupis (Member # 833) on 04-02-2004, 12:42 AM:

"Its been many hours and many days
That carbon just went awayyyyyyyyyyyyy
Because NOTHING COMPARES
NOTHING COMPARES to CARBONNNNNNNNNN"

[Smile]

Posted by Frank Angel (Member # 248) on 04-07-2004, 06:21 AM:

There is no reason why carbon arc lamphouses could not have been engineered to burn longer rods so that full features of 2, 2.5 hours or even longer could not be accomodated. It is really just a quirk of history that the xenon technology hit before anyone thought of redesigning the carbon arc system. Once the advantages of xenon became apparant to the exhibitor -- teh adv advantage, btw, had nothing to do with the quality of light on the screen, but everything to do with his ability to run multiple screens using automation and eliminating mulitple projectionists salaries -- it caught on like wildfire. There is nothing that will give an exhibitor a hardon faster than saying he can run 15 screens with a single projectionist instead of 15 projectionists. Before the manufactures of carbons and carbon arc lamphouses could unveil a competing long-play carbon arc system, everyone was running mesmerized to xenon, which, as we all know, never dies before its rated life, never explodes before the reflector's rated life and never, EVER flickers!

Has anyone ever done a study (I mean anyone other than xenon manufactures) that compares the light output per watt for carbon vs xenon? I have a 40ft screen that has a beautiful picture -- bright with excellent contrast and burning carbons at 3200w (80Ax40V). According to one of my suppliers, that screen would need a 4000w xenon for the same bright image. If this is true, then over not a very long time xenon could be much more expensive compared to carbon if the extra cost of energy consumption is figured in.

Posted by Steve Kraus (Member # 476) on 04-07-2004, 08:43 AM:

I'm not sure how wide the cone of light emerging from the positive crater actually is but just in general seeing the relatively shallow mirrors within a carbon lamp vs. the deep reflectors of modern xenon lamps I have to wonder what sort of fantastic light outputs might be possible with a carbon arc lamp designed around a state of the art deep reflector. Perhaps a xenon unit could be adapted or maybe this would have to be specially designed using modern optical CAD techniques. Deep but with a small notched out area directly above the arc flame.

2+ hour operation is not a problem but how well did those automatic positioning systems work? They were pretty crude, no? Imagine what could be done today. You could really have a fully automatic lamp that needs no attention at all over the course of the show. Autostrike, too, of course (probably mechanical but I'd bet a xenon ignitor would work too).

Posted by Gordon McLeod (Member # 33) on 04-07-2004, 08:44 AM:

The Morganite AutoArc was designed to bun the 16" copper clad positive and could operate for 2hours unatended and also had an autostrike feature

Posted by Robert Throop (Member # 61) on 04-07-2004, 10:40 AM:

Jim,
What lamphouse are you burning 11mm positives at 60 amps? What size negative are you using?

Posted by John T. Hendrickson, Jr (Member # 849) on 04-07-2004, 10:54 AM:

I just spent yesterday afternoon at the Count Basie Theatre in Red Bank, NJ with our tech, Bob Peterson from New England Theatre Service, adjusting the Peerless Magnarcs in preperation for a screening next Monday night.

We are putting out fantastic and steady light on the 39 foot screen with those two old gals. Still have some minor adjustments to make on the carbon feed motors, but overall we are ready to roll.

Since the Basie only runs film sporadically, it doesn't make sense to convert to Xenon. As long as we can maintain the Magnarcs you will be able to view film by arclight there.

Posted by Jim Spohn (Member # 1547) on 04-07-2004, 11:42 AM:

Robert... I'm running 11mm X 20" high intensity positives with 11/32" negatives in an RCA "Brite-Arc" made by Ashcraft. This is a water cooled lamp with the carbons being rotated by a ratchet rather than the usual chain drive. We push this lamp gently, on projector #1, to match the light of an Ashcraft Suprex being pushed hard on #2. Amaisingly the intensity and color of the light matches fairly well. Change-overs are seemless. I actually have two of each lamp, but by running one of each, I can burn almost any carbons that I can get my hands on!! ... Jim

Posted by William H. Ward (Member # 1797) on 04-20-2004, 04:26 PM:

Let me ADD my 2 cents worth of BS on this subject. Although I am now retired, my love for the carbon-arc still lives on. There are no theatres in my town that use them. I'll drive miles just to watch a pair of carbon-arc searchlights work the skys. I've worked in booths (many) for 25 years on all kinds of carbon arc projection lamps. You cannot beat them for their smell, sound, drama and light output. They did have to be maintained to have trouble free operation. When xenon first begin to emerge, I remember some company had put together a lamp burning 11mm positive carbons and had a carbon magazine on the side which fed a new one to the lamp for continous burn. I don't know about the negative carbon.
xenon just overtook everything. You cannot beat a well trimmed carbon-arc projection lamp burning its'trim at the maximum amperage for that trim and most important, fed from a good GENERATOR. The arc is very smooth, quite as a burning candle and the generator supplies a constant DC voltage which does not vary with changes in the house AC voltage.
Here is some more. I would like to see how a projectionist burns an 11mm positive carbon at 60 amps. as mentioned in these replies. Erratic feeding, very small if any crater formation and most important, no gas ball present. Your carbon life would be good, but your light terrible and a blue in color. I will always be a carbon guy to the very end. Frankly, I do not see how the industry can go back in technology usage. Zenon is here to stay whether we like it or not. The very best lamps ever made was the Peerless Magnarc and the Ashcraft Super corelight. Anyone ever work the the Strong Jet-arc? Massive, carbon eaters, lots of light output, noisy, 21" reflector and it won the Academy Award for technical achievment in the late 60's. I don't feel zenon will top that. Sorry some of you professionals missed this era.

Posted by Bill Enos (Member # 440) on 04-20-2004, 11:44 PM:

Is anybody open 365 days a year 2 or more shows per day still using carbons? If you are, where are you getting carbons? We ditched the Magnarcs primarily because the supply was erratic at best and the quality was terrible. The newest Marbles went up and down in brightness, sputtered, hissed, one even popped so forcefully that it blew the arc out. I thought they were damp so I took them home & put 'em in the oven at 150F for 3 hrs. No good, they were just crap.

Why would anybody need a tech to adjust Magnarcs, it takes only a few minutes once they are hot, any only a few minutes more to learn how to do it.

Posted by Daryl C. W. O'Shea (Member # 1303) on 04-20-2004, 11:49 PM:

I recently got some National Carbons from Robert Film Service in Montreal. I haven't used them yet, but I don't imagine I'll have any problems with them.

Posted by Phil Hill (Member # 371) on 04-21-2004, 01:34 AM:

So Bill, do you still have those Magnarcs laying around collecting dust? If so, I'd be interested in them....email me please.

>>> Phil

Posted by Jim Spohn (Member # 1547) on 04-21-2004, 10:04 AM:

William, We burn 11mm positives at 60 amps. To get the feed correct I had to put a resistor in series with the fuse for the motor. Our crater is good and complete with a nice plasma field. Several members from this forum have been to my theatre and will tell you that our light isn't blue at all (actually it is first class). I have been burning carbons for over 40 years and consider myself to be compident and knowledgeable, I bought an entire theatre just so I could run my carbon-arc equipment. If 60 amps didn't give us good light, we would increase it(DUH). We run at 60 amps because it works not to save carbons. I have no main office or manager to answer to. If it didn't work we wouldn't do it. Our theatre is a specialty house not open to the public for regular showings, I do screenings of recent releases for friends and we do silent movies with a Wurlitzer pipe organ for different groups. Please, if you enjoy running a change-over booth as much as I do, feel free to come operate the booth. Pictures of the booth can be seen from the front page of this forum under "Granada Theatre Bakersfiled 10-08-03. Even our 16mm projector is carbon-arc. ... Jim

Posted by John T. Hendrickson, Jr (Member # 849) on 04-21-2004, 03:21 PM:

Bill Enos wrote:

"Why would anybody need a tech to adjust Magnarcs, it takes only a few minutes once they are hot, any only a few minutes more to learn how to do it."

I would, Bill. Because:

1. I have not run arcs for over thirty years.

2. My experience was with Ashcrafts. I only ran Magnars a few times as a relief operator.

3. The Peerless J's at the Count Basie Theatre had not been operational for a number of years, and needed some major attention beyond my area of expertise.

I hope that I will never become too old, too smart, or too proud not to call for assistance when I need it.

Incidently, we must have done something right. New Line was so pleased with our presentation of their private sneak of Laws of Attraction that they want us to do another one for The Notebook.

I hope this answers your question/statement.

Posted by Christian Appelt (Member # 1067) on 04-21-2004, 03:35 PM:

What about the carbons from India, I believe that Monee still makes arc lamps, so there should be supply for them. Did anybody try those?

Posted by Daryl C. W. O'Shea (Member # 1303) on 04-21-2004, 07:37 PM:

Those carbons aren't great, but they work. It's really hit and miss with them.

Posted by Bill Enos (Member # 440) on 04-21-2004, 11:49 PM:

There was a thread a while back about the Indian carbons, Schultz is the name.

Posted by Mattias Ohlson (Member # 1662) on 04-22-2004, 01:16 PM:

I am sorry to ask a basic qustion but..
Average life of a cinema xenon arc lamp at 1kW, 3kW and 7kW
What is the cost of bulbs at those energies if you are in a position to get a decent price?

Posted by Ian Price (Member # 14) on 04-22-2004, 03:13 PM:

1 KW = 3,000 Hours
2 KW = 2,000 Hours $400 (I get about a year out of these.)
3 KW = 1,200 Hours $600 (I go through 3 per year in one machine.)
4 KW = 1,000 Hours
5 KW = 800 Hours
7 KW = 800 Hours

I run each machine about 3,000 hours per year with 4/5 shows per day, 365 days per year.

So a 2K costs me about 14-cents per hour. A 3K costs me 50-cents per hour.

Posted by Mattias Ohlson (Member # 1662) on 04-22-2004, 03:46 PM:

Thank you Ian.

Posted by Frank Angel (Member # 248) on 04-24-2004, 07:41 AM:

Only problem when figuring cost, the first time a xenon blows up and takes a miror and/or electronics with it, the costs get way screwed up. Carbons never took out a $1000 mirror.

Posted by Bill Enos (Member # 440) on 04-24-2004, 07:52 AM:

True, carbons never shattered a mirror, but with the money we've not spent on carbons, we could buy a stack of mirrors and still have several thousand dollars left over.

Posted by Richard Fowler (Member # 893) on 04-24-2004, 09:13 AM:

When Kneisley was making xenon conversion kits their sales literature displayed the cost savings on carbon and electric...the end result showed a payback in less than two years.....today with more competition, xenon is even more less expensive. I have had cracked mirrors from leaking carbon arc jaw water jackets.

Posted by John T. Hendrickson, Jr (Member # 849) on 06-15-2004, 08:03 PM:

I will be firing up the Peerless Magnarcs one last time at the Count Basie Theatre in Red Bank NJ on June 21 at 8PM for a private screening of "The Notebook" for our subscribers.

Film-techers in the area are invited. Just mention my name at the door and come on up to the booth.

The Basie took delivery today on two L-5000 lamphouses from Big Sky Industries, along with N3X150 rectifiers. Conversion will take place in July while the theatre undergoes a complete seat replacement with new Irwin seats.

The end of an era. We will remain a changeover house as the XL's (circa 1955) keep on ticking.

Posted by Stephen Furley (Member # 1277) on 06-16-2004, 02:24 PM:

A sad day John. What was the reason for converting in the end; lack of decent carbons, cost?

About three quarters of the places I knew that were running carbon three years ago have either converted or closed since then. I think the very last regular users may well go within the next year or two. I doubt if there will be anywhere, even occasional users, in five years. To the best of my knowledge, we're now down to just one regular public cinema in England still on carbons.

Posted by John T. Hendrickson, Jr (Member # 849) on 06-16-2004, 04:20 PM:

Right on Stephen. The difficulty of getting decent carbons was one reason, along with the fact that a benefactor offered to foot the bill for conversion.

Second problem was finding folks who know how to run carbon arcs. I work the Basie as a volunteer for the sheer love of being able to take a step back in time. Thus far, no one else has come forward to assist in running this booth. I run the booth operations at a nearby multiplex full time, and I don't have a whole lot of time (or for that matter patience) to train newbies to run arcs and changeovers.

I can't be in both places at once, and I'm not getting any younger, either, even though the Basie is a special venue theater that has live performances and concerts and does not run film that often.

Posted by Joshua Waaland (Member # 287) on 06-23-2004, 08:53 PM:

Okay. Time to resurrect an old thread. I have been reading this thread trying to learn about carbons so I can run the Peerless type G's I just bought. I read a post by Warren that said he put his carbon rods on top of a warm rack to keep them dry.

I work for a company that makes automated welding equipment. Many of you may already know this, but carbon arc rods are used in the welding industry to back gouge steel plates. If you have made a mistake welding something you can use a back gouger with a carbon rod to remove the material. It makes a herendous sound. Anyhow we have sold electrode ovens for years to welders to put their welding rods in to keep the moisture out. The more moist the rods the more porous the weld. We even sell little carry around paks called Ted-Paks that dispense one electrode at a time and they keep moisture out.

We just recently branched out and got our first sample of carbon rods in from China. We are going to start selling them. (Finally my career and hobby intersect, Yeah!) [Big Grin]

They are different than projection rods in that they have a hole through the center of them. Do you guys think that putting carbon rods in an oven at a low temperature would harm them? It may help the moisture issue for those that still use them of course. If you are interested in seeing the ovens they can be seen here.

http://www.gullco.com/products/ovens/ovens.htm

Josh

Posted by Warren Smyth (Member # 1838) on 06-24-2004, 11:15 PM:

quote:
do you guys think that putting carbon rods in an oven at low temperature would harm them?

No, it's unlikely to to cause any harm Joshua afterall, the carbon gets pretty hot when burning in the lamphouse - 6,000 degees C at the tip in fact. As I said, it's a good idea to have just a few in the lamphouse next to the side door ready to be used. This aids a quick change and helps dry out carbons prior to use, as the lamphouse is a good oven.

It often kept my tea warm as well, untill I got a moment to eat it in the days of two projector changeovers.