# Specs Shmecks!

#### Dreadpoet

##### Active Member
How important is it to stick to factory specs when considering lamps to purchase for my ERS's? All of my ERS's are throwing from a distance of about 20 to 30 feet...so I figure that I will find a lamp that will suit them all....rather than have eight different typs of lamps. I'm really having trouble getting a nice smooth wash. I see that some of the instruments can share common lamps from specs provided by ETC/Altman/etc... but I'm not happy with their output. I realize that FEL's may end up being the death of my instruments...as they get so blummin hot...what do you think???

#### Van

##### CBMod
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Premium Member
How important is it to stick to factory specs when considering lamps to purchase for my ERS's? All of my ERS's are throwing from a distance of about 20 to 30 feet...so I figure that I will find a lamp that will suit them all....rather than have eight different typs of lamps. I'm really having trouble getting a nice smooth wash. I see that some of the instruments can share common lamps from specs provided by ETC/Altman/etc... but I'm not happy with their output. I realize that FEL's may end up being the death of my instruments...as they get so blummin hot...what do you think???
Heck as long as you don't mind your reflectors melting, Your gels burnin out in 2 minutes, and the risk of overloading the design spec's of the internal wiring of your fixture, Put whatever lamp you can cram in there. So what you spent $250 on a s4 shove an FEL in there and burn it up in an hour,drip some molten aluminum on you audience, at least you'll saved yourself the troubled of having to stock the proper lamps. #### CowboyDan ##### Member I believe that Van said exactly what I was thinking. #### Footer ##### Senior Team Senior Team Premium Member Your unevenness is not coming from your lamps, its your fixtures. You should have the same type of fixtures doing 1 thing, then the same type of fixtures doing another thing. Not the best idea to mix and match. And with the others, sure shoving a 1k lamp in the rear of a 360 or 360q sounds like fun now, but when you start having reflectors going left and right, you'll rethink that. Stick to what the fixture was made for. #### gafftaper ##### Senior Team Senior Team Fight Leukemia Use the proper lamp... unless you like fire. Your uneven problems could also be because you need to clean and do a proper bench focus on all your instruments. Do a search on bench focusing there's lots of good info on how to do it correctly in this forum. #### Van ##### CBMod CB Mods Premium Member Use the proper lamp... unless you like fire. Your uneven problems could also be because you need to clean and do a proper bench focus on all your instruments. Do a search on bench focusing there's lots of good info on how to do it correctly in this forum. See that is the proper way to respond, constructive,helpful and informative. I guess I was just cruising through snideville this morning. Sorry 'bout that. #### ship ##### Senior Team Emeritus Premium Member How important is it to stick to factory specs when considering lamps to purchase for my ERS's? All of my ERS's are throwing from a distance of about 20 to 30 feet...so I figure that I will find a lamp that will suit them all....rather than have eight different typs of lamps. I'm really having trouble getting a nice smooth wash. I see that some of the instruments can share common lamps from specs provided by ETC/Altman/etc... but I'm not happy with their output. I realize that FEL's may end up being the death of my instruments...as they get so blummin hot...what do you think??? Factory spec. in recommended lamps for the fixture is not always published and updated as new lamps come up. The spec. sheet tells you what lamp the fixture was UL listed to be used with at the time it was brought to market. UL listing is your theater's liability insurance. Stuff like if the fixture gets too hot by way of a non-spec. lamp, it might cause a fire on other gear that's closer than I believe it's nothing closer than a flame resitant 18" from the fixture to any surface. That could burn down your theater. Use of other than a factory approved lamp in any fixture will void the fixture warranty much less any liability these fixture manufacturers have on the gear say should the theater burn down because of the fixtures. On the other hand, often there has been new lamps brought to market and tested after the specification was published which might or might not be updated on the "approved lamp" specification sheet. Call the manufacturer to verify "approval" of the use of any lamp not on the spec sheet. For instance on a Altman #100 3" Fresnel. Doesn't say it's rated for a 150w ETC lamp yet it's the lamp most often used with it. Call them and they do approve of this lamp, it's just not in the specs. For instance on the S-6 Shakespheare, since it's already rated for a 750w EHG lamp, Altman probably never at the time of publishing tested the HPR 575/115, GLD, GLE or #6981P. All of these lamps have only been on the market a few years. Believe it has been updated in specs for the GLA and GLC lamps, but if not, all above lamps with permission from Altman would most likely be approved of by them. Depending upon what specific type of fixture you have, you can given the throw distance fairly well standardize you lamps down to something like two. Just have to make some choices. Below is a selection guide as it were to simplify it for you. It would be much easier if you stated what specific fixtures you were using = "Altman" could mean a G-9.5 (Medium Bi-pin / TP-22) for most of their fixtures, E-11 (Mini-Can) as an option on most of their fixtures or extended incandescent/halogen lamp P-28s (Medium Pre-Focus) for their older Lekos / all ERS fixtures. I'll take on the two most common fixture, if using something different such as a mix of radial, axial and S-4 in the inventory, or some architectural mini-can Lekos, such lamps can be speced out in the same way in a follow up. First, As others have said, a smooth even wash is often a bench focus problem, but the proper lamp and a good choice in it can also help on stuff like the "Altman dark spot." If S-4 fixture, it's an HPL series lamp - no choice, a TP-22 type lamp will fit but won't be retained by the S-4 fixture which uses the heat sink to retain the lamp. Lamp will work but if you move the fixture, the lamp will most likely fall out. That heat sink will also prevent the HPL lamp from fitting into most other Altman like fixtures in the industry. Don't blame us for lack of standardization, blame who at your theater bought the fixtures if standardization in lamps is your priority. Could always E-Bay the S-4 fixtures and buy any number of brands that will allow for a unified lamp choice. Otherwise: If and only if you can find any discontinued GLA+HS Philips #29430-6(518767) (#6992P/S) which is a TP-22 type GLA with a Removable Heat Sink, you have a universal lamp that fits in all fixtures. Such lamps went off the market about five years ago. I have like a case of them left but am not selling them. Or perhaps I'll do a special to the industry "guy wants to standardize his lamps special" Let's do$50.00 per lamp. You can remove the heat sink once you have it and re-use it on new lamps. ETC does not recognize this lamp and does not recommend the use of it, but it's not against the rules to sell lamps already in stock. Optically in a S-4 fixture, the HPL series lamp is probably better anyway - the GLA/Sink or GLC/Sink version of it would work but as a theory at least was not as refined in providing an even wash according to ETC. It's all about how the filament grid verses filament rack is arranged, the HPL series lamp is copywritten and cannot be used on other types of lamp I believe as the reason it's not a standardized filament. None the less, a GLA and GLC lamps' 9x7.5mm Planer Filament should be fairly close in providing a flat field similar to that of a HPL's 6x9mm single coil square filament. Never tried the Phillips heat sink lamps in a S-4 so I don't know. What would be interesting would be removing the removable heat sink from this lamp and installing a Osram HPR 575/115 lamp into the Phillips sink base. Curious to see what the internal reflector lamp with a FLK filament would look like. Did try a FEL in a S-4 using one of the removable heat sinks... Not pretty. As below notes about light loss out of a FEL lamp, you could not get an even field out of a FEL inside a S-4 fixture. This much less it was not all that bright.

So, if you have a ETC S-4 type of fixture, you have 10 lamp choices. Let's refine your choices so it's easy. (Unless dimmer duplexing.)

Simple enough to decide: 375w, 575w and 750w.

Choices are the HPL 375w/115v/C, HPL 375w/115v/X, HPL 575w/115v/C, HPL 575w/115v/X, HPL 575w/120v/C, HPL 575w/120v/X, HPL 750w/115v/C, HPL 750w/115v/X, HPL 575w/120v/C, HPL 750w/120v/X.

Of these choices, I would do 575w for that throw distance.

Next is voltage: 115v or 120v. I would do 115v as 120v gets really dim and is more used for architectural installs, plugging directly into a wall socket or where you have lots of voltage spikes.

Next is long life verses high output / short life. For a school, I would use long life - it's more cost effective.

Simple & Done for a S-4 fixture. HPL 575w/115v/X extended life is what I would recommend.

For a TP-22 based fixture it's much the same types of choice as above these days, only the lamps are slightly different.

Wattage, 400w, 500w, 575w, 750w. In wattage for that throw distance and when matching up with a S-4 as best possible, there is no real reason to do other than a 575w lamp.

This is the HX-400, HX-401, EHD, FLK (HX-600), FLK/LL (HX-601), GLC (HX-604), GLA (HX-605), HPR 575/115, GLD (HX-754), GLE (HX-755), EHG and #6981 series of lamp.

Voltage, 115v or 120v. Unless as above you have voltage spikes etc. a 115v lamp would be choice and match up in color temperature with the S-4 fixture.

This limits you to the GLC, GLA and HPR 575/115.

Long life or high output. Again for a high school, I would lean towards the long life lamps.

For long life, the only real choice at that wattage/voltage is a GLA lamp.
Otherwise for high output and if doing Gobos, the GLC lamp is probably better.
For high output and a more even flat field the HPR 575/115 with internal reflector has boosted output and a more flat field across the beam.

Again simple enough once it's laid out and given process of elimination choices. My recommendation is two lamps. One for the S-4 fixture, the HPL 575w/C, the other for the Altman's a GLA.

After that, you can use other lamps for special purposes and specials as needed but in general, these lamps should be good enough and cost effective for general usage.

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#### ship

##### Senior Team Emeritus
Premium Member
I see that some of the instruments can share common lamps from specs provided by ETC/Altman/etc... but I'm not happy with their output. I realize that FEL's may end up being the death of my instruments...as they get so blummin hot...what do you think???
If the output on 575w extended life lamps is not sufficient, and given you are now using long life lamps, you have three fairly easy choices. Otherwise just skip a step to the next step above what doesn't seem bright enough.

Before you do this however, bench focus your gear so as to make sure what seems dim isn't because the lamp is not focused in the reflector. If not focused - all lamps no matter the wattage will be dim and off.

Deciscion in getting brighter is to use either high output but -300hr / 575w lamps, or if you have the dimmer capacity, going up to a long life -1,500 to 2,000hr / 750w extended life lamp. Beyond that, high output -300hr / 750w lamps are the most powerful rated for the fixtures.

Again simple...

First boost up in output up from the long life 575w lamps =

high output 575w lamps:
For the S-4 HPL 575w/115v/C & for the Altman GLC or HPR 575/115 dependant upon projection verses wash needs.

Next step up in intensity =
750w extended life:
For the S-4 HPL 750w/115v/X and for the Altman GLE

Final step up in intensity =
750w high output:
For the S-4 HPL 750w/115v/C and for the Altman the Phillips #6981P

As others say, you can install a FEL in a Altman Leko - that's an old rock and roll industry trick. Do you have big budgets to constantly replace lamp bases and reflectors, much less re-paint it due to peeling paint and heat damaged now rusted parts? FEL with it's huge filament was just a big heat source anyway. 750w lamps at 115v with something like a 9.5x9.3mm filament instead of this 1Kw lamp at 120v with a 7x18mm filament means that in a fixture designed to reflect light from a point source, a lot of the light given off by the FEL lamp is going to be just stray light waves that is chopped off by the fixture's gate, shutters and lens train. In other words, sure, the FEL is big and powerful but much of the light that's produced never leaves the fixture. Test it.

Besides, a Osram #54582 FEL-R lamp is much more powerful than a normal FEL. Unfortunately they were discontinued years ago.

Beyond that, why not go for 1.2Kw. Ushio still makes a #1000972 lamp that's called the "JCV 120-1200w/CH" which has 17% more output than a FEL, and 100% chance it's going to melt down something on the fixture.

As long as you can fit the 7/8" bulb into a reflector normally sized to fit a 3/4" lamp, you are golden with 3,250̊K; 33,000 Lumens; and a whopping 200 hours of lamp life.

Mmm, More Power.

This lamp with some modifications to a Altman #1000 follow spot might be of interest on the other hand.

#### Dreadpoet

##### Active Member
Actually Ship...that was very helpful. Part of the reason I had posted this was to draw you out into another conversation on lamp choices. I saw a post you put up a long time back. It made me curious.
I just started working for this junior college a year ago. They have some of the strangest assortment of instruments I've seen. I have some axials that I know originally had asbestos cabling…I can’t even find a label on them to describe who made them. Looking at the strange stepped lense in them...It took me a while to figure out what to consider calling them. I also have S4’s, 360q's etc. So I inherited a large gambit of instruments…which sometimes creates difficulty in creating a smooth wash. FEL’s and FCV’s were being used in some of the instruments….but as I said….I’m not to happy with that. I also really don’t like the EHG’s that are rated for many of the instruments I own. Something about the quality of light that I just can’t put my finger on. So when you started talking about HPRs I got curious.
My old school axials are taking EGG’s…I’m trying to make these instruments disappear from my stock.
My S4’s are currently taking HPL750w…I’ll take your note on moving down.
My oldschool 3.5's are taking EHD’s...again, so old I can't even find out who made them.
I’m just looking for something to work in my other ERS’s (360q’s….etc, which make up the bulk of my wash) to help get similar quality of light to aid in creating a wash. I’m no fool….a perfect wash with my inventory is difficult at best.

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#### Van

##### CBMod
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Premium Member
They have some of the strangest assortment of instruments I've seen. I have some axials that I know originally had asbestos cabling…I can’t even find a label on them to describe who made them. Looking at the strange stepped lense in them...It took me a while to figure out what to consider calling them. quote]

Hmmm An axial ERS with a stepped lens I'd bet a Dollar they are Kleigls.

#### cutlunch

##### Active Member
Dreadpoet when you are talking about steped lenses do you mean the lens has a circular pattern on the lens? Or do you mean there is more then one lens in the unit? I am just curious. If it is the first I probably know it as a fresnel.

Any chance of some photos of these old lights for interest sake?

#### Dreadpoet

##### Active Member
Oh, I've got some kleigels too. I don't mean one with two plano-convexes. I mean one with a single stepped lens. I'm thinking that it wants to have double plano-convexes, but someone used their stepped lenses from their kleigels instead. Mabey on purpose...I dunno

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#### dbn

##### Member
Step lenses are different from fresnel lenses. Both are "reduced glass" equivalents of plano-convex lenses. In a stepped lens, the front surface is a smooth convex, and the back surface is a series of flat, concentric "tiers", with the deepest "cut" at the center. Think of the shape of a "step pyramid". The edges of the steps were often coated with a matte black ceramic substance to reduce stray refractions. My high school had Century Lekolites with 10-inch step lenses.

#### Van

##### CBMod
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Premium Member
Step lenses are different from fresnel lenses. Both are "reduced glass" equivalents of plano-convex lenses. In a stepped lens, the front surface is a smooth convex, and the back surface is a series of flat, concentric "tiers", with the deepest "cut" at the center. Think of the shape of a "step pyramid". The edges of the steps were often coated with a matte black ceramic substance to reduce stray refractions. My high school had Century Lekolites with 10-inch step lenses.
Exactly the diference between a fresnel lens and a step lens is that te fresnel lens has a marbled back The marbling produces the soft edge indicative of a fresnel fixture. The stepping on te lens really doesn't care which side it's on , back or front, plano or convex, as the angles of refraction and reflection are all that really matter.

Ok Bonus question;

What was the Stepped lens originally invented for and why ?

< sorry about typos tha last few days. My old keyboard crapped out so I pulled one out fo storage apparently the t r g and a couple of other keys don't work to well. I'm trying to pry the Office depot card out of Rosalies hand as we speak>

#### fredthe

##### Active Member
What was the Stepped lens originally invented for and why ?
I always thought it was for lighthouses, to reduce the weight of the lens. But I may be wrong...

#### dbn

##### Member
I always thought it was for lighthouses, to reduce the weight of the lens. But I may be wrong...
Might have been, but I always thought it was the fresnel lens that was developed for lighthouses. I've seen some 18th century examples (in museums).

#### Van

##### CBMod
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Premium Member
Yes, Both correct, Actually the fresnel lens is a "stepped lens" Although we in theater often think of a fresnel lens having te pebbled back surface, He, AJ Fresnel invented it as a way of reducing weight in Lighthouse lens, which didn't have pebbled backsides. If they had they would have been very good lighthouses would they ?
A stepped lens can be stepped on the front or back The fresnel lens is a version that overcomes a lot of issues that arise from stepping the backside of the lens. Weakness and Depth to name two.

#### gafftaper

##### Senior Team
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The legend from before time that I've been told is that they had a problem with quality of the glass production back in the ancient days. The thickness of the glass would build up heat and the lens would break. This was particularly a problem in light houses where they wanted to focus light over a great distance so they needed a big lens. Good old Mr. Fresnel realized that if he took the basic convex lens and then removed concentric rings of glass he could still approximate the correct curve, get a decent focus, and create more surface area for cooling. With the rings removed he saw he could also squish the thickness of the original curve down into a thinner glass as well but the rings that remained would still cause much of the the light to focus to a point.

A true stepped lens followed this idea as well of approximating the correct convex curve but removing glass rings creating more surface area for cooling and keeping the glass cooler.

#### Van

##### CBMod
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Ok OK now what is the law / rule,describing the behaviour of refracted light?

#### fredthe

##### Active Member
That's easy... Snell's law.