Fresnel Lenses

[SteveB]

My problem with the Altman 1K6FR fresnel doesn't start or stop with the lense.

We've had these units probably 20 years now, so they were in the early production run. The unit is UL listed at 1000 watts and our lenses started cracking soon after we lamped up to 1000 watts.

I contacted Altman directly, with Mrs. Altman - AKA as Charlies wife, informing me that they now had an insulator for the lense/fixture bracket.

That told me 2 things. 1) The design for the fixture I had was faulty, if it now required an insulator and 2) I was not the only person to complain as they obviously had to come up with a solution - thus the insulators.


OK, so there's a design issue and this is not an upgrade, it's a repair for faulty design.

My thinking is that I paid good money for a product UL rated to 1000 watts and that I should not be replacing one of the primary components - the lens. If the lens fails at 1000 watts, then the fix is a repair, not an upgrade. Period. And if you as a dealer try to tell me the insulators and better reflectors are upgrades that I have to buy, well you just lost me as a customer.

Altman declined to provide replacement lenses for the 4 that were broken.

A note that this is back in the days when Altman had a loose arraingment with it's dealers and you could order new units and parts directly from Altman. Perhaps working with a dealer would have solved some of my problems, but back in those days the larger NY area shops HATED dealing with Altman for parts (instrument parts were poorly documented) and the alternative was Universe Stage Lighting and Scott was very slow, and in truth I know folks at Altman, having grown up in the area, so why go to a dealer.

I was also aware that they were not going to pay for the labor - which in any case was not significant, but I would have liked some sort of good faith attempt to keep me as a happy client, maybe a tee shirt ?, which was not forthcoming, just a "here's the insulators - best of luck".

A few years later, the original reflectors stared melting. These were the type with a flat aluminum plate and a small (1-1/2") parabolic button reflector pop-rivited to the flat plate.

I called and discovered they had a new design, a traditional 5" (approx.)round style reflector that I could BUY.

Hmmm... another case of they've changed the design when they discovered a flaw, only this time it's not free.

We purchased a compete set for the 20 fixtures we used at 1kw. The reflector swap was done during summer maintanence and was a royal PITA and cost us a goodly amount of labor.

Currently, when I focus a unit, I have to point the fixture horizontal to move the focus to spot, as the sliding tray is worn out.

OK time to replace, but they're going to be Colortrans. We purchased a dozen a few years back. No broken lenses, no melted reflectors, no ugly brown edge at flood.

Likewise the TV Center has had Strand 6" 1k's for years with no issues, though they like their Mole's and Arris' a whole lot better.

Oh, did I mention my issues with the Shakespeares in the road house ?.

Steve B.

 

[Mayhem]

Ok - some more "thinking out loud" on my part when it comes to the possible causes. Keep in mind that like my vibration from the lens cracking causing the lamp to flicker - this is also simply a hypothesis.

I keep hearing about these insulators for the lenses and I must admit that I have not come across them before. I have some Prolite 500/650 Fresnels in which the lens does not have any insulators to hold it in place.

So, I wonder if these are designed more to keep the lens protected against being pinched than they are to stop heat transfer (as the term insulators would apply). Do they in fact protect the lens from being cracked by to retaining brackets?

If I have read the previous posts correctly – the insulators are some sort of fibre based product which will no doubt allow for compression, as the bracket expands.

We all know that metal expands when hot, so it is feasible to think that the lens could be compresses between the fixture and the retaining brackets, thus placing force onto the lens. Also, as the brackets are not all that large in terms of surface area, the point load force could be enough to cause the lens to crack.

So – that is my hypothesis on this and I’ll now welcome any thoughts or comments that may either prove or disprove it.

 

[Les]

Why is it that the 1KF requires insulators but the 65Q needs none at all? I think that the fixture in question was just really old and happened to break. I'm sure there are ways to avoid broken lenses, but no way to actually guarantee it from happening again. It's possible that the design of the 1kf places the lamp closer to the lens. The ventilation seems good, but I have also had a 1kf burn through a gel in no time even in the flood position. It just makes me think that the entire lamp assembly in the 1KF needs to be moved back. I have never seen a 65Q old or new with a broken lens. I have had 10 year old 1kf lenses crack in to 4-6 large pieces and a one year old 1kf lens crack in half- each fixture was of the same type, but one was manufactured 10 years ahead. Also I think that the flickering lights were just a figment of the imagination, or just a coincidense.

 

[ship]

Just finished fixing one of three work lights over my work table today. I have a 75wPAR 30, 150wInkie, and 100wJDR/MR-16 over the work table, and only the MR-16 fixture on a constant basis fails in a colorful way. We have phase harmonic issues so lamps blowing is not unusual, only in this case more so than the other two. Concept of the mechanics car in being the last he works on in off hours is the same as my own work table. Turns out that the fixture both had welded hot prong and it’s neutral had even melted down or warn away to an extent that it’s rivet attachment to the neutral had also broken loose and showed melting. Plus the base and it’s mounts had rusted either by way of past water or the heat. Either one of the two, bad contact to hot or bad neutral will have had the dimming/buzzing effect especially for the first minutes in turning it on each day. Much less before this the blowing of the lamp as a constant basis.

Vibration... don’t know about that other than as it relates to heat and arching. One would think that effects on the filament would be retained within the lamp capsule other than as stated as vibrations of light and heat. I know the lamps worked in a bad lamp base and that lamp acted at times like a florescent lamp on a bad ballast. What given no lens was noted however was that in the case of a bad lamp base that would tend to have the after effects of dimming of the lights, and as theory the pressure thing, it was very much noticeable that the lamps in this fixture blew sooner than the others as might have been noted to the description.

The above debate however is on spring leaf retainers that as opposed to metal directly in contact with lens need insulators. Separate story.

Vibration/wavelengths as an effect on the lens in front of it. Good theory, study into it but I expect that even that would require a certain weak spot to the lens to make it break up.

That’s my reading at least.

A final thing might be in given a noted lens breaking safety issue, perhaps some screen to retain the lens will be necessary. A good stainless steel hardware cloth if available ½" on center should be sufficient when welded into a gel frame to retain the lens should there be a problem without effecting the light output. Just a thought. Had to install some screening on some Q-Lights of late. It worked well as needed.

 

[SteveB]

To Lester and Mayhem

The insulators I've used were for the Altman 1k6FR series fresnels, which is Altmans only 6" 1000 watt fresnel.

I don't know if they ship this model currenly with the insulator - it's a white square fabric that resembles the fibertex type fabric that fire curtains are made of.

I would doubt that the 65Q uses the insulator as it's a 750 watt rated unit, and has a history as a durable and useful unit.

My guess with the 1K6FR is that the design, while larger then the 65Q, for whatever reason, doesn't cool as well as desired with a 1K lamp, coupled with a different lens retaining system (4 clips) that possibly allow the clips to get very hot, transferring heat to the lense.


The 20 that I operate at 1K have not had lenses break with the insulators, nor have we had issues with the new reflectors.

I was never thrilled with the beam edge at flood though, and have alway's found the tolerances of the gel holder a bit tight, making installation of barn doors (Altman barn doors at that !) difficult at times

SB

 

[Les]

mounting position may have something to do with it. I have usually used them focused straight down, maybe it puts stress on the lens? I doubt it, but I guess its more common than I thought. I think that there are not enough vent holes in the back of the unit. I have also never had problems with the reflectors.
I agree with the gel frame mounting. Also, I'm not too crazy about the focus handle. I would prefer a wingnut or screw system. Something that would lock into place.

 

[tadawson]

SteveB led me to think of something which might be going on here . . . since the lens is only held in with 4 "clips", then depending on whether the case is hotter or cooler than the lens, these will create either hot or cold points on the perimiter of the lens, which can set up brutal thermal stresses in the glass. If the insulators stop this heat transfer and even out the lens temp, then perhaps that is how the problem is solved . . . .

- TIm

 

[Mayhem]

SteveB led me to think of something which might be going on here . . . since the lens is only held in with 4 "clips", then depending on whether the case is hotter or cooler than the lens, these will create either hot or cold points on the perimiter of the lens, which can set up brutal thermal stresses in the glass. If the insulators stop this heat transfer and even out the lens temp, then perhaps that is how the problem is solved . . . .

- TIm

Well this was my thinking with regards to uneven distribution of heat. However, I wonder what the difference would be between the heat transfer from the lamp and that from the four clips?

 

[tadawson]

The lamp would tend to induce a pretty even heat distribution, I would think, with cooler stress points where the uninsulalted clips would sink off the heat to the chassis of the instrument . . .

- Tim

 

[ship]

I'm thinking in staying out of dealer/end user battles or what is warranty verses what's as per design to the best of the manufacturer's knowledge and UL testing to the date you bought it more or less as is. A computer has constant upgrades, while often free, it did not come out the same as it is now in use. A fixture than if used within the same way before problems were found than might still work without a problem in a cost effective way to the price you bought it at. All manufacturers have upgrades, and most of the time they are not free or all inclusive. If you buy a 1940's Chevy would you expect to send it back to have seat belts and air bag to be installed for free?

When I buy a Par Can or Audience Blinder fixture, amongst other fixtures I might even be manufacturing from ground up, I'm mostly buying them un-wired in fact. I have seen the shortfalls in UL-Listed design of many fixtures and tend to make my own improvements to the design for servicability better than what's provided. Nothing is perfect, look at the industry debate of what's the best Leko.

I much support Steve on but also take offense to in some ways he stated his thoughts against dealers in general or my opinion. While good to point out the problems he has found and I'm now aware of them, I was taking offense to the opposition to me as a dealer speaking as a tech person as if other types of sales person or in some sense of not looking out for the customer but also being tech person. Steve in knowing what he is doing does and should contact the manufacturer directly, but the dealer often will support in addition to this. What's better, one person in asking or both dealer and tech person asking? Don't discount the use of a second source.

I looked at my own 1KAL fixture. It's clips do have it's edge not it's surface of the metal directly exposed to the lens. But yep, I do act as dealer and would as perhaps unusual support the client in putting my own weight behind his issure. On the other hand, I would also be realistic in even for me, I might try to get something that seems right but won't push the issue if beyond the norm or reasonable and turned down. While at times I'm much more qualified than my own dealers to do what I need to do, or constantly take offense to college punk or washing machine sales people for dealer sales staff, it's not all inclusive in lots of exceptions. Much less, while all gear has certain problems, stating one brand of gear is bad in general, is normally a bad point of view to take. Even American DJ has at at times had compitent sales people, much less does produce some quality gear.

However, beyond perhaps a most likely scratching of the lens and causing problems than in this internal to the fixture mounted retainer, the clip with only say a 18ga by 1/2" long portion of metal touching the lens should not have much effect upon heat transfer.

Might be more this fairly sharp edge's effect on the lens in pressure onto it, but had it been the easy solution, beyond testing, UL might have noted such a thing. UL tests the safety of the fixture, but should the lens rain down in a shower of glass, I'm sure it will not have gotten even a listed for it's wiring.

Still a chipped or scratched lens will often function well enough withoug causing problems so it's more a side issue perhaps of a opposing lot number of lens.

The Studio Fresnel line of fixture from them comes with more a dual leaf spring clip that has the pads on it. Often I'll be replacing these pads as somethin not unusual. McMaster sells a 2" by say 60' rolloof the stuff you install with double sided tape. Given an upgrade of clip style, the pads themselves if the lens is extracted will probably need replacement anyway.

Still if focused doward, since these clips are inside the fixture, the direct weight is on the fixture frame and lens door casting. That is while perhaps also in use of a padding is what holds the weight of the lens. Since that's the case and the spring clips are not perhaps over the stage bouncing around in the back of a truck, than that spring clip with it's edge touching the lense is sufficient in not causing damage.

I'm at least thinking that the lens breaking issue, no matter the upgrade, was less because of the spring clip than something else when used on stage.

That's my theory at least, given while I have this fixture, I'm normally only using it at 500w. Than again no matter the brand when a fixture has problems, I'm normally the one to fix it.

Since I'm yet to see this problem no matter what the wattage, I'll take it under advisement that the lens might break, and perhaps even add a screen to the fixture should I max out it's wattage, but in the end don't expect to need a upgrade. I would be interested to hear what the upgrade is, but don't expect it's need.

 

[SteveB]

Ship,

Thanks for the reply and the discourse, and an apology if any offense was taken, but some thoughts...

"I'm thinking in staying out of dealer/end user battles or what is warranty verses what's as per design to the best of the manufacturer's knowledge and UL testing to the date you bought it more or less as is."

I'm thinking that as a dealer you're in the unfortunate position of being in the middle. I don't envy you and understand the situation you're in

."A computer has constant upgrades, while often free, it did not come out the same as it is now in use."

All true, but any computer comes out of the factory working as specified, and if it doesn't, it gets replaced. I had 9 mos. of registry errors with my very first Gateway before they admitted it needed replacing. They did not replace it with an identical unit.

The Altman fresnels in question were tested and specified as being a 1000 watt rated unit. The lenses cracked and the reflectors melted when used as specified - a 1000 watt unit. Thus they are not working as specified and regardless of how they tested, problems develop in the field and it is the responsibility of the manufacture to fix the problem, especially as cracked lenses could conceivably disassociate itself from the fixture and injure someone. Colortran went Chapter 11 from the cost of having to fix thousands or early ENR dimmers that melted when used in the field, regardless of how they tested out and the UL rating. They did not charge their customers for the fixes. A reputable manufacturer does not charge to fix problems, even if the problem crops up later in use.

“A fixture than if used within the same way before problems were found than might still work without a problem in a cost effective way to the price you bought it at. All manufacturers have upgrades, and most of the time they are not free or all inclusive. If you buy a 1940's Chevy would you expect to send it back to have seat belts and air bag to be installed for free? “

As I stated in my posts, the fixtures did not work as specified once we lamped up to 1000 watts. The age of the unit is normally irrelevant, but in this case it was less then a year from the time the fixture was purchased and the problems with the lenses occurred.

To use the car analogy, Toyota is recalling hundreds of thousands of vehicles that have problems. They are not upgrading the vehicles, they are fixing them so that they work as specified.

As a side note, as with any car manufacturer who discovers a problem that has safety implications, it’s the responsibility of the manufacturer to NOTIFY the end user that a potential safety issue as cropped up and that a free remedy is available. Altman was aware of the lenses cracking issue, else they would not have developed a fix (insulators), but they did nothing to notify the end user.

Further, an upgrade is when I add functionality and or features that IMPROVE the fixture beyond the original design.

A software bug and or hardware issue with an Express console is a fix. Adding Emphasis is an upgrade. ETC has steadily released new OS’s to the Express/ion line as free upgrades that fix software bugs (as well as providing for free upgrades, thus they have the right to call it an upgrade). Calling it an upgrade doesn’t change the fact that it’s fixing the problems and in the examples of ETC and Colortran they are not charging as they feel it’s their responsibility to fix problems.

“I much support Steve on but also take offense to in some ways he stated his thoughts against dealers in general or my opinion. While good to point out the problems he has found and I'm now aware of them, I was taking offense to the opposition to me as a dealer speaking as a tech person as if other types of sales person or in some sense of not looking out for the customer but also being tech person. “

My only comment that anyone might take offense to was that at the time Universe Stage Lighting was sometimes slow to respond to parts issues. No one to take offense actually, as they are no longer in business. And I made no other offensive comments about any other dealers, merely stated that facts of the situation I encountered at the time.

I admit though to being puzzled as to why you are having a problem understanding the (clients view of a) difference between a fix and an upgrade, as it’s pretty clear to me.

“Steve in knowing what he is doing does and should contact the manufacturer directly, but the dealer often will support in addition to this. What's better, one person in asking or both dealer and tech person asking?

Again, a read of my earlier posts states that I might have (and do now) work with the dealer system, but AT THE TIME, the dealer system was a bit less defined, and it was perfectly acceptable to call Altman directly. As stated, other NY area Altman dealers did not like having to deal with parts, mostly as Altman had not yet done as good a job as they do now in documenting the parts system. Now-a-day’s, you have to work with a dealer, and it’s a good thing as the manufacturer mostly doesn’t have time to handle the individual requests from thousands of customers.

In closing, please be aware that my comments are about issues that happened no earlier than 15 years or so ago. It’s entirely likely that everything has changed, but remember that the very original post was asking about lenses cracking in general, and I was merely stating my experiences and was clear in the posts as to the general time that my problems occurred.

But the bottom line is that as a customer, I will form an opinion about the products I use and that I have a right to my opinion, which in this case is a learned opinion. I have 30 years of experience as a stage lighting technician and have used countless products from many manufacturers and will continue to form opinions that are not just from my own experiences, but also from those of my colleagues and fellow workers, but also from the very good information that the web now provides for.

My opinion based on my experience with the Altman 1K6FR is that it was a defective product and that my experience with Altman in getting the fixture to work as specified was very unsatisfactory. Based on that experience and more recent un-happy experiences with other Altman products have caused me to not want to buy other products from Altman (except the wonderful PAR Cans and Ground Cycs !).

SB

 

[ship]

We pound heads, but there is no animosity in discourse and that’s great and educational to all no doubt. I act more as a end user than dealer. Buying something like 96 outdoor PAR units . My responsibility is the lamps and clamps, someone else normally buys the fixtures. I fix problems subsequent to that. No answer from Altman by the way on some slight issues found on some of our 66 similar fixtures in stock. If it becomes systemic beyond something noted to a few fixtures than you bet I’ll be contacting them further. Not perfect as a company, but given past ETC debates ongoing also even longer about some even more serious issues I have. No manufacturer of lighting equipment will ever be perfect.

Interesting note and history of the Colortran dimmers, but a dimmer is more like a new car than that of a say a TV that should last it’s warranty but afterwards is not ensured to be trouble free. One hopes but can’t be sure. Not all will have problems and never buy into the extended warranty.

I still contend that it’s bought “as is” and it’s not unusual to need to replace reflectors or lamp bases as normal maintenance - especially a few years down the line. Could have had a bad lot number which is it’s own battle - I have seen this before. Between Altman and Strand Fresnels, that’s a fairly constant replacement thing, and on a 5K fresnel, the Strand reflector will wear out faster. Look at the 360Q line of fixture with it’s various upgrades to lamp base and reflector. In the past there was constant problems with the old style HT lamp base with aluminum heat sink. Never had a problem with them but was well aware of others having problems. Since than, they have been upgraded as technology improved. My own Studio Fresnel line of 2K and 5K fixtures have either had to have a few $K worth of upgrade to the newer lamp base or in the case of the 5K, sent back to the factory for an upgrade that took years to implement and also cost a lot of money both in parts and especially in shipping. This or deal with lamp bases that just did not last more than a few years and need resurfacing probably once a year if in constant use. Replacement lamp bases as a serious mistake by Altman became discontinued at least a year before the first upgrade thus I had to buy out stock all over the country in old style lamp bases and learn re-surfacing. This as opposed to the Strand lamp base that rarely needs replacement but does at times, or the Mole Richardson ones I posted photos to that were even of a worse design that the Altman. Mole fixtures and bases that are at least double in price to that of the Strand or Altman are even less effective than that of the old style Altman. Get a crack in a 10K Fresnel lamp base and you could have some serious problems, yet you pay for the better high tech porcelain upgrade lamp bases. All to say nothing of if you drop a Lycian 1290 follow spot that will cost about $4K to repair before shipping.

Lens / safety issues with this fixture is something serious but is it something that’s unique to your application or something that is systemic. I agree that if it’s something that is constant you should have the upgrade. You did have the upgrade provided, but if in doing so it’s not necessary to replace the lens, it would not be provided. A fight for replacement lenses you replaced to date because of the design flaw is a good debate and separate from the upgrade itself. Hard to get in touched with owners. Bought mine as used from Design Lab in Chicago. Good luck in them figuring out where I live even if they wanted to reach me to tell me about the upgrade. No serial number or tracking available. Fixture notes than is the only way to announce upgrades and there might be one on the fixture. While not the best way, it’s reasonable to just post fixture notes for upgrade.

On the Altman buying from debate, you are correct in stating your opinion. I have problems with all companies from Reich and Vogul to Color Kinetics at times. As you stated, while you have problems with some fixtures from Altman, other fixtures are fine for the most part. As should be. The 1KAL series never rally took off on the market. Given it’s more narrow beam spread and tendency to fall out of focus, I probably would not buy into it’s line either. While less in years of direct experience in many ways, my own is that it’s a company like any other company. Often what you pay for is well worth it from them as decently reliable. I just take a different standpoint on stuff like reflectors and lamp bases at times in assuming either lot number or in questioning our use and maintenance or situation as a factor. Bought a cheaper alternative to Thomas 8-Lights at one point. They while bought un-wired because not even Thomas lights live up to my standards, the fixtures themselves are crap. In general, much from China is crap but not all. Domestic brands of fixture are slightly more dependable.

To be more exact, this lens issue I think was more about a 65Q problem. Not must posted about lens problems with them or any similar fixtures with lenses breaking. The 1KAF fixture than is probably not such a good line and not to be recommended, but the 65Q perhaps is very dependable - especially over what comes from China. If setting up a new theater, I would probably go for the 65Q line, or if I needed 1Kw fixtures would probably go more with the 1000L line of fixture. Exclusion of them in coming from Altman than limits the choice of what’s available and cost effective.