# Fixture Questions



## ship (Dec 26, 2005)

306) To focus a S-4 from soft to hard focus, you move the lens train which way from the lamp?
308) Patterns go in up-side down or right side up?
309) What is the relationship between the diameter and the thickness of a lens?
310) What is the Altman #100 3" Fresnel Inkie rated for in wattage? What is the normal Wattage and ANSI lamp used in it?
314) Why are stage lighting fixtures not recommended for use at home?
315) Why are moving lights illegal to use at home in reference to harmonics?
321) Why are normal mirrors bad to use with lasers?
327) Moving the focus towards the lens at the same time as closing the Iris will do what to a follow- spot?
328) What is the difference between a step lens and a Fresnel Lens?
329) What is the difference between an ellipsoidal and parabolic reflector?
336) When a C-Clamp is finger tight on a pipe, how much more should it be tightened to support a fixture even if roostered out?
337) What is the difference in beam between a Ellipsoidal, Spherical and Parabolic Reflector?
338) Bright spots in the beam of a Leko is generally caused by what?
339) What is the use of a top hat installed on a Leko?
340) Which should be done first on a leko: Run the barrel to focus the instrument or the shutter cut, why?
341) How long should you wait before replacing the lamp on a standard moving light?
344) On a Coemar Panorama Cyc, what address would the third instrument have?
345) What is the cause of fuzzy images on a technobeam?
346) What is the pan and tilt capacity of a Studio Spot?
347) What does Fchn 025 on a Colorram II do?


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## krhodus (Dec 27, 2005)

308) Patterns go in up-side down or right side up? 


Up-side down. The mirrors inside the light will flip them to be projected right side up.


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## kingfisher1 (Dec 27, 2005)

329: 
A parabala and its 3d cousins only have one focus point (at lamp)

ellipesodails have two focus points (lamp and gate)

Therefore (please correct me if i'm wrong) a parabolic reflector send all the light straight out where as in an ellipsodial reflector all the light converges at one spot. this is why you can project stuff with ERSs


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## soundman (Dec 27, 2005)

336) When a C-Clamp is finger tight on a pipe, how much more should it be tightened to support a fixture even if roostered out? 
No more than two turns. 


340) Which should be done first on a leko: Run the barrel to focus the instrument or the shutter cut, why? 
Focus, shutter cuts will change once the light has been focused.

341) How long should you wait before replacing the lamp on a standard moving light? 
This is really a question for the bean counters, in some productions it might be once the go out, in others it might be once a % of the total hours has been reached. 

344) On a Coemar Panorama Cyc, what address would the third instrument have? 
5-6

345) What is the cause of fuzzy images on a technobeam? 
The difference in distance from the top to the bottom of the image makes it hard to focus?

346) What is the pan and tilt capacity of a Studio Spot? 
Pan 370 tilit 255

347) What does Fchn 025 on a Colorram II do?
Sets fan control channel.


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## ship (Dec 27, 2005)

kingfisher1 said:


> 329:
> A parabala and its 3d cousins only have one focus point (at lamp)
> 
> ellipesodails have two focus points (lamp and gate)
> ...



Sounding good to me except it sounds in description like the ERS is a less efficient type of fixture by way of light output. Wish to refine some? Also in refining this observasion, what's a "Go Fres." How than does it work and what is it similar to?


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## ship (Dec 27, 2005)

soundman said:


> 336) When a C-Clamp is finger tight on a pipe, how much more should it be tightened to support a fixture even if roostered out?
> No more than two turns.
> 
> 
> ...



You is good...
336) Please define further what two turns means. Given you normally turn a screw 1/2 a turn per turn or is it a full rotation of the screw thus 360 degrees? How than is this different than normal tension and past finger tight norms?
340) Hey, that resembles me in being the buyer of lamps where I work. Or prick in general. Be glad that you are not where I work or if you don't know the specific nomenclature of the lamp you request, ... you go back to find out what lamp you would wish in not being ready to swim with the big fish. Or otherwise wasting my time and not knowing what you wish for or knowing what the heck you are doing as a "professional." What, I don't use these fixtures, I don't need to know what lamp is in a X-Spot - you in changing the lamp should know. Also if asking a IA boy for a HMI 1200 lamp, you expect the follow spot to other than get a Mac 2K lamp by accident? Much less in a true follow spot HMI 1200 lamp, was that a HMI 1200w/SE or HMI 1200w/GS? That's an important type of thing to know beyond the oterwise common HIM 1200w/S amongst other HMI 1200 lamps.

Beyond actual verses expected lamp life and change before lamp life or when the lamp dies - sometimes three very different figures, it was a question instead of how long most manuals specify you should let the lamp cool. For a Mac 2K in lamp life, it's for the most part a 750 hour lamp. Philips in a "change before" specification says you should change it before 1,000 hours. On the other hand, I don't find it unusual to find these lamps lasting well beyond 1,500 hours at times in working just as well as a lamp with 20 hours. At lest this by way of our "expert" or "we only hire the best" staff in balancing one fixture to another for a show. This given blue or green ceilings or other wee obsicales such as snow truss roofs and lots of other things like time in the way of a true comparison between lamps.

While bean counter by way of I yell at you, my boss yells at me when he gets the few $K replacement lamp bill at the end of the month and none of are happy, it's all the same. Need a replacement lamp? Here is one that looked "brown" in one fixture. Give it a try again given it only has 500 someodd hours. If it still looks brown after two other ballasts/fixtures - each with it's own voltage signature, perhaps it is brown. Until than, you get nothing new until you use up the old lamps that should still work. How is that for being a mizer or saving my own rear or profit sharing as a bean counter proper?



In not checking the rest of the answers, ... very impressive and well done.


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## Inaki2 (Dec 27, 2005)

ship said:


> Hey, that resembles me in being the buyer of lamps where I work. Or prick in general. Be glad that you are not where I work or if you don't know the specific nomenclature of the lamp you request, ... you go back to find out what lamp you would wish in not being ready to swim with the big fish. Or otherwise wasting my time and not knowing what you wish for or knowing what the heck you are doing as a "professional." What, I don't use these fixtures, I don't need to know what lamp is in a X-Spot - you in changing the lamp should know. Also if asking a IA boy for a HMI 1200 lamp, you expect the follow spot to other than get a Mac 2K lamp by accident? Much less in a true follow spot HMI 1200 lamp, was that a HMI 1200w/SE or HMI 1200w/GS? That's an important type of thing to know beyond the oterwise common HIM 1200w/S amongst other HMI 1200 lamps.




Its true!!!


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## dimwatt (Dec 29, 2005)

> 338) Bright spots in the beam of a Leko is generally caused by what?



I'm a freshman when it comes to Lekos, having only just acquired my first one (actually a batch of 6 of them - I have a few queries about them that will appear elsewhere soon).

I believe the bright spots are caused by the lamp not being centrally aligned in the elipsoidal reflector. The alignment can be adjusted by the three screws on the end of the cap, arranged in a triangle around a central screw. This central screw adjusts how far the lamp sticks into the reflector.

I haven't tried it yet, but if any of my Lekos have bright spots, then I plan to point the instrument at a plain surface, the surface being perpendicular to the beam of light. Then I'll tweak the screws until the bright spots (and any dark spots) disappear.

Perhaps I'm wide of the mark - and if so that's fine, as just like everyone else I'm here to learn.


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## kingfisher1 (Dec 29, 2005)

Once again i may be on shakey ground here...

ERSs are just as effecient because once the light passes throough the focal point it is then pointed in the right dirrection by the lens. I find one flaw here, which may be explained, if the second focus pointis at the gate, the theororetically, all the light would be converge at one infinatly minute dot, there fore a gobo would not work....

then again, with the same logic a gallileain (calperican? one of those old guys...) telescope wouldn't work

then again the ellipses may not be perfect ellipse or something....

does anyone have an optics map of an s-4 or something?

Q: 339) A top hat would be used to sharpen the the edges correct? this is similar to a donuohgt thing right?


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## ship (Dec 29, 2005)

Try not to preface one’s post with a best guess, lack of experience or worry of posting wrong answer. It’s either to the best of your knowledge or what you think reasonable, but when the stage hand in a live mode asks you a question what you answer in being the same based upon your answer is just as important if not more so to be correct or to check one’s facts in giving an answer.

One should not worry about intimidation or fear of being wrong in stating one’s mind or thought as much on line. We all make mistakes or don’t fully know or field, we also all have some extent of understanding that needs reinforcement and even some extent of renown as it were given something we hope we have mastered. Lots of stuff I and we all don’t know sufficiently, what is important is that we don’t stop learning when and every time something comes up that is important to remember. Too bad often what’s important to remember does not come up sufficiently to necessitate being more than on the tip of one’s tongue. Perhaps in learning it is more the feeling one gets when something just does not feel right, and a good memory for where in your notes or books you reference such a question, and less a photographic memory.

If of any help, I intimidated a IBEW Master Electrician today.  All in the job or what is must know for me verses others where by in a serious way programming fixtures by way of binary code makes me at best scratch my head or find someone able to do so such as I am useful to them.

Jack of all trades and master of nothing or specialist that is lost in other parts of the field. You choose to what extent your involvement and knowledge overall after a base to all.

Such questions I ask are probably good questions to study and know. On the other hand, it’s much better to answer even if wrong or not fleshed out sufficiently, than to not answer but instead answer your stage hands asking you in the live mode something wrong or confusing both for you and them. On line is the place to gain more learning - this especially with what you don’t know sufficiently and think would be useful to know. This before in loading in a show you get asked the question and answer wrong, or right but are not sure.


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## ship (Dec 29, 2005)

kingfisher1 said:


> Q: 339) A top hat would be used to sharpen the the edges correct? this is similar to a donuohgt thing right?



Correct, but has one studied why one would use a tophat instead of a donut?

What's the difference in using each type of clean up or accessory and why at times use both? This answer than would be important to know for all designers in what effect the top hat has in projecting patterns in supplement to a donut in helping one's design or not being necessary. Those designers that don't know the answer are not quite ready to fully use the design tools available to fulfill their concept yet it would seem. Thus this question than becomes important.

What is this difference and when do you need or not need the added top hat?


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## kingfisher1 (Dec 30, 2005)

Does a top hat, unlike a dounut, reduce spillage? like if you had a fixture that was nearby a curtain, flat, a part of the ceiling, and unwanted light was spilling onto bad places, a top hat would slightly elliminate that.

"One should not worry about intimidation or fear of being wrong in stating one’s mind or thought as much on line"

"the only stupid questions are the one's which people fail to ask."

(my wisdom for the day)(actually i'm pretending i'm wise by copying other words of wisdom...but they still remain wise words  )


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## Radman (Dec 30, 2005)

306) To focus a S-4 from soft to hard focus, you move the lens train which way from the lamp?

Closer


308) Patterns go in up-side down or right side up?

upside down and backwards


309) What is the relationship between the diameter and the thickness of a lens?

thicker lense larger diameter


310) What is the Altman #100 3" Fresnel Inkie rated for in wattage? What is the normal Wattage and ANSI lamp used in it? 

100W ESR


314) Why are stage lighting fixtures not recommended for use at home?

high temperature lamps, high current draw and possibility of old, out of date wiring (like my home, try ceramic things in your floorboards)

all in all one big fire hazard


314) Why are stage lighting fixtures not recommended for use at home?

I expect it might have to do with the ballasts causing unwanted interference with other home equipment.


321) Why are normal mirrors bad to use with lasers? 

laser can burn through coating on back of mirror


327) Moving the focus towards the lens at the same time as closing the Iris will do what to a follow- spot?

dim it


328) What is the difference between a step lens and a Fresnel Lens?

step: _| fresnel: /|

or in words, the step lens has right angles at the edges of the layers, while the fresnel has a different angle


329) What is the difference between an ellipsoidal and parabolic reflector?

ellipsoidal is less even than a parobolic


336) When a C-Clamp is finger tight on a pipe, how much more should it be tightened to support a fixture even if roostered out? 

I'll admit I'm horrible at this, I crank those suckers down (I get it from my dad) but I'd guess about 1/4-1/2 turn, depending on the softness of the pipe


337) What is the difference in beam between a Ellipsoidal, Spherical and Parabolic Reflector?

spherical would be super wide, par would be more focused, and ellips more focused yet, with hotter center


338) Bright spots in the beam of a Leko is generally caused by what?

darker spots elsewhere (perhaps gobos)  

improper bench, or dirty lens/gel (especially if the gell is scribbled on alot, I did that once)


339) What is the use of a top hat installed on a Leko?

to get rid of any extra spill out the front


340) Which should be done first on a leko: Run the barrel to focus the instrument or the shutter cut, why?

I wanna say barrel first to get it in the ball park, then shutter, then if necessary fine tune the barrel


341) How long should you wait before replacing the lamp on a standard moving light?

The expected life of the lamp.


Never used moving lights before (OK once but not very in depth, no play time, and not those, instruments)


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## ship (Dec 30, 2005)

This is not a technique I have studied or done enough other than for other designers to fully experiment with either. Your concept holds merit in clean up especiall for field angle spill from a shutter cut.

By concept, the donut acts as a second gate/iris to clean up the other than direct beam of light. The tophat might be used to further clean up this beam in having a longer spill catching tube to catch all but the beam angle.

That's my take on it, but again it's not something I have installed other than for other designers to further clean up a beam of light from a pattern in places where the image had to be very graphic.


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## kingfisher1 (Dec 31, 2005)

Top hats are also useful to minimize audience abuse w/o comprimising your positions


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## Inaki2 (Dec 31, 2005)

Donuts help make gobos cleaner. They may reduce some intensity though.

Top hats prevents flare fromt he fixture to shine on the audience's eyes and walls, etc. They're a great accesory when doing theater.


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## falcon (Jan 2, 2006)

Stage Lights at home?

Not good, huge fire hazard due the high current they typical draw (mosly the old ones, new ones draw less). Household wiring is either romex or bx cables in the new homes, knob and tube (ceramic knobs that hold the bare wire (more older homes, insulated in the later homes) in place) in the old homes. The knob and tube can barely handle modern household devices so stage lights will cause it to fail. The houses with romex or bx cables can't handle the draw of the lights combined with what else is on the circuit. Typically, 12 devices to a household circuit, so 4 lights, 2 switches and 6 outlets. So if anything else is running with the stage lights on, it could trip the breaker or if the house is improperly wired, (which does happen, i've seen it on brand new construction) there could be arcing that may result in a fire.


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## kingfisher1 (Jan 2, 2006)

although, if your really desperate for stage lights in your home, ands you have too much money, ETC makes a bunch of archetectual products that are basically the same as the theater stuff just rated for lower amounts of power (and household use)


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## Inaki2 (Jan 2, 2006)

Someone as ship about this...garage full of 'em.


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## ship (Jan 2, 2006)

Radman’s response. 

309) In mis-stating the question, what’s the mathematical formula for beam spread for a specific size and height of a lens.
321) What about where the reflector is located or quality?
341) I'm more thinking time before accessing, touching and changing a lamp that goes bad.


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## sound_nerd (Jan 2, 2006)

Step lens has the cuts on the inside of the lens, and is not commonly used if I am correct. If I remember correctly it is the lens used in the parilellisphere fixtures. The fresnel lens has the cuts on the outside surface of the lens.


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## ship (Jan 2, 2006)

sound_nerd said:


> Step lens has the cuts on the inside of the lens, and is not commonly used if I am correct. If I remember correctly it is the lens used in the parilellisphere fixtures. The fresnel lens has the cuts on the outside surface of the lens.



Very good, why use one over the other or why don't Fresnels use step lenses?


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## kingfisher1 (Jan 3, 2006)

'cause its more fun to say fresnel :wink: ?


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