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5k fresnel- powering from a generator?


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#1 Patrick Lavalley

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Posted 30 May 2007 - 02:59 PM

I am shooting a senior thesis project this summer, and one of the scenes calles for a night exterior. We don't have the money to rent an HMI, so we were thinking of going a bit cheaper and using a 5k tungsten light, and renting a 7500 watt Honda generator from a hardware store to power it. My question is first, will this work and be safe? And also, will we need any special adapters to distribute the power from the generator to the light itself? We are still early in pre-production, so we're feeling out our options as far as the lighting for this scene goes. Another option might be to try and rent a 2500 HMI and a smaller generator. Any help/suggestions would be GREATLY appreciated. For reference, we will be using an HVX200 with a RedRock 35mm adapter and Nikon Lenses.

Edited by Patrick Lavalley, 30 May 2007 - 03:01 PM.

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#2 Stuart Brereton

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Posted 30 May 2007 - 03:11 PM

A 5kw tungsten lamp will work fine on a 7.5kw genny. However, it's output will be around half of what you'd get from a 2.5k HMI, even less if you're going to put gels on it.

For a night exterior, it's hard to beat an HMI, particularly if you're using it for 'moonlight'. But if money is the issue, it's probably cheaper to rent a bigger genny, and hire a 10kw tungsten lamp, rather than to get HMI and a smaller generator.

I believe an HVX200 with a RedRock (or similar) works out at about 80asa.... On a night exterior, you going to need the biggest lamps you can get your hands on
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#3 Patrick Lavalley

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Posted 30 May 2007 - 03:25 PM

Thanks for the suggestion. I suspected as much about the power of the 5k versus an HMI. I'm trying to push for an HMI, but we'll see how that goes. I just took a quick look, and it seems like the price of a 10kw tungsten and a 13kw genny would be about the same as a 2.5kw HMI and a smaller genny. Most likely we will have to gel the light, which would really cut down on our output. It's hard to convince them to spend the equivilent to our entire food budget on a single light, but it's really going to be necessary if they want to properly expose our night scene.....
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#4 timHealy

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Posted 30 May 2007 - 04:52 PM

If a may make a suggestion ... you may want to approach it from another point a view. Call it a shoe string budget idea. You may be able to find 1k pars or par cans much more affordable. In fact you may find you can get a whole cartful or pars for the same price of an HMI. Since it is a night shoot you can kind of "paint" with them and hit areas that are important and let othe areas go dark instead of hitting a whole area with one light.

If you use several pars from the same general area it will look like one light.

And you have the option of using 1200 watt firestarters for punch and heat, or you can easily use 1k wides, narrows or mediums for wider spreads and less intensity. Be sure to get scrims too.

Generally speaking many people don't use HMI's at night. They can be troublesome with headers and ballasts and micro switches and the like. Sure you can and people do, but tungsten is usually cheaper and easier.

Another idea when renting: You can tell them it is for a shoot on a Monday and you need to pick em up on friday and return on Tuesday. So then you get 4 days for the price of one. Or tell them you need it for the week and they may give you a one or two day rate then pick up on a friday and return the following monday.

Good luck

Tim

Edited by timHealy, 30 May 2007 - 04:55 PM.

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#5 Brian Drysdale

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Posted 30 May 2007 - 05:21 PM

And you have the option of using 1200 watt firestarters for punch and heat, or you can easily use 1k wides, narrows or mediums for wider spreads and less intensity. Be sure to get scrims too.

Generally speaking many people don't use HMI's at night. They can be troublesome with headers and ballasts and micro switches and the like. Sure you can and people do, but tungsten is usually cheaper and easier.


Tim


I'm sure about the reasoning here, HMI's are no more complex to use at night time than they are during the day. They're often used on night exteriors, especially when moonlight effects are required over large areas. Tungsten has the advantage of being cheaper, however, I'm not so sure about it always being easier. For one thing it takes longer to rig a lot of small lights to create the effect of one large light source, and you can have the problem of multiple shadows.

Unfortunately, we haven't heard the type of shots or style being planned on this production.
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#6 JD Hartman

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Posted 30 May 2007 - 05:23 PM

When you choose a generator, you have to check the specifications for its continuous output. This is especially true with the smaller portables. A Honda 6500, only delivers 5500 watts continuous. I'm not sure about the Honda 7000, but it won't deliver 7000 watts except briefly. To connect your 10k, 5k or 2.5k HMI, you'll need adapter between the 60a bates and the generator receptical.
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#7 Patrick Lavalley

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Posted 30 May 2007 - 09:27 PM

All good suggestions. I might be getting an internship at a rental house soon, so I might be able to swing a deal to get an HMI from them, and a generator, but trying to come up with a plan if that doesn't work out. For reference, the piece is a western, and there will be a person carrying a lantern along a trail, it will probably be lightly wooded. I was also thinking of using a china ball for fill, and to try and motivate it as if it were coming from the lantern. Since we won't be able to light a huge area, I think we will be saying somewhat close...
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#8 Riku Naskali

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Posted 31 May 2007 - 03:41 PM

Well, I like Tungstens at night. Although if power is an issue, I would try to push for HMI's. They're just that much more efficient. But tungsten has its advantages. No need to wait for them to cool down when restriking, theoretically no flicker problems and of course they are really cheap to rent.

Of course you could rent flicker-free ballasts, etc. but the price will go up a notch.

I would go tungsten if my main source was motivated by man-made lighting. If you want that blueish moonlight, gelling tungstens makes absolutely no sense. Of course you could make your moonlight blue in transfer, filling with warmer sources thus keeping them neutral.
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#9 Stuart Brereton

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Posted 31 May 2007 - 04:07 PM

There's no absolute right or wrong here - tungsten lamps can be great for night exteriors in urban environments, but as Patrick has said, it's a period piece in a wooded area, so I'm guessing it's a moonlight effect. Combine that with the fact that an HVX + RedRock needs an awful lot of light, and there really isn't much of a choice. It's HMI's all the way.

Old style Wire Wound ballast HMI's are a lot cheaper than Flicker Free, but their output tends to be less, and you have to be careful with with your FPS.

Why not have a look at one of these: Tower Light . They are 4kw metal halide lamps so will have that cool look to them, are built on a 10kw genny, so you can run other lamps of it (and make coffee at 4am) and are relatively cheap and easy to get hold of. They're probably not flicker free, but neither is a wire wound ballast. They're pretty quiet too.
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#10 Mike Williamson

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Posted 31 May 2007 - 06:30 PM

One issue that no one has mentioned is that if you're using HMI's, you need a generator that has a crystal controlled hertz rate. Some of the Honda generators have them installed, but I think that's usually done by motion picture rental companies that have modified them for film shoots, not from your local hardware store.

I shot a low-budget feature last summer where we carried a Honda 6500w generator to power our "big gun", a 2.5K HMI for day interiors. When transferring the footage later in telecine, I noticed there are a number of scenes that have flicker from the HMI, which we're stuck with because we can't reshoot. It could be due to poorly run cables, but it's also playing with fire to use a generator without crystal synch. I should mention that we did have a flicker-free ballast, which shows that it can happen with those as well.
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#11 Ralph Keyser

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Posted 31 May 2007 - 06:37 PM

Does anyone have experience shooting with lights like the Tower Light?
You see them used a lot to light construction projects at night, and in large quantities at night time events. I've even seen a version with what looks like a large china ball at the top of the tower. They don't look to my eye to be the same color temperature as typical HMI, and of course, they don't come with lenses or any other control features. But, they do put out a lot of raw light, and the tower cranks a good distance into the air. Sort of a combo Condor, genny, and light. They might be something to keep in mind for a really low budget moonlight source. The generator is far from being quiet enough for dialog recording though.
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#12 timHealy

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Posted 01 June 2007 - 10:23 AM

I'm sure about the reasoning here, HMI's are no more complex to use at night time than they are during the day. They're often used on night exteriors, especially when moonlight effects are required over large areas. Tungsten has the advantage of being cheaper, however, I'm not so sure about it always being easier. For one thing it takes longer to rig a lot of small lights to create the effect of one large light source, and you can have the problem of multiple shadows.

Unfortunately, we haven't heard the type of shots or style being planned on this production.


If your comfortable using HMI's at night then by all means keep doing what your doing.

But Tungsten is easier than HMI's for all sorts of reasons. If you don't believe me then just ask your electricians.

Tungsten: few things can go bad. The head, the bulb, the header cable. All can be easily repairable by your typical set electrican on set or at your electric truck.

HMI's: Many things can go bad. The head, the ballast, the header cable, the striker, the freq, the bulb, micro switch, hot restrikes, failure to strike because of grounding issues and/or generator issues and/or voltage drop, HMI par lenses tend to break, you cannot do continuity on bulbs, you cannot read voltages coming out of the header cable (maybe a tech can)
Most of these things have to be fixed in the shop by technicians who have more experience in electrical engineering and maintainence techniques. Usually the only thing a set electrician can do is determine which piece of equipment is bad and put it on the scrap pile to be sent back to the vendor.

About the rigging time: I was suggesting two or three par cans. If you don't have time for that then you may be a very impatient person.

About the shadows: if you put three par cans on three stands next to each other and hit three different spots on your set, it'll look like one light and you won't have to worry about shadows.

I was trying to give him a low budget alternative if his one HMI was too expensive. Also if any part of the HMI fails the show is over. Alternatively if he has a bunch of pars cans, one broken one won't shut down the shoot.
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#13 Matt Workman

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Posted 02 June 2007 - 10:40 AM

I like Tim's idea with the PARs. Kevin Zanit owns a truck load, shown in a previous thread. I'm thinking of using a few on my next feature.

To add one more factor to this is power kick outs. I own a few HMI's (electronic ballast) and I lost power several times and the fuses on the ballast blew. This doesn't happen on Tungsten lights. You can turn them off just by unplugging it, probably not the best idea on a 5k.

HMIs need more TLC but if you can keep them happy they are like we've said WAY more efficient. For a quick and dirty shoot you are probably better off with 1K open faces or something ilke that, especially without a Movie Gennie.

I'm pretty sick of powering my HMI's from crappy house power and having it die mid shoot. Its expensive.

Cheers,

Matt :ph34r:

Edited by Matt Workman, 02 June 2007 - 10:42 AM.

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#14 Patrick Lavalley

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Posted 02 June 2007 - 10:53 AM

Hey Everyone,

Thanks a lot for all the help and suggestions. All of them are valid, and all seem like good ideas. I think for this set of shots, our best bet is going to be to get the generator and run the 5k off of it, and supplement it with 1k's that we can get for free from school (and run off a seperate, borrowed lower powered genny of course). It has come down to a cost/benefit thing. This will be a relatively small scene, so we'll have to do the best we can with what we're able to get. Another thing that we want to do is get one of those Chimera china balls for some soft fill, does anyone have any advice about those?
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#15 Brian Drysdale

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Posted 02 June 2007 - 03:14 PM

Using an HMI for a night exteriors depends on what want to use it for.

You can light larger areas with the larger HMIs like the 4k to 12k lights. If you've got a large area to light, the large HMI will be a lot quicker to rig than numerous PAR CANs, plus the possibly of having to conceal both them and the cables within the shot.

In the UK the 2.5K HMI has the advantage that you can just plug it into the wall without needing a generator or a mains tie in.

HMIs are no different to other pieces of equipment, you should rent well maintained gear. In this regard, a night shoot is no different to daytime shoot when you're also relying on your lights to be operating correctly. If your "sun" through the window dies, the effect is just the same.

As has been mentioned, tungsten works extremely well for urban areas, but if you need to light an entire field for a moonlight effect a large HMI is much better. It's a matter of picking the correct tools for the job. In this case there were a number of options available.
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#16 Jim Feldspar

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Posted 03 June 2007 - 10:29 AM

One issue that no one has mentioned is that if you're using HMI's, you need a generator that has a crystal controlled hertz rate. Some of the Honda generators have them installed, but I think that's usually done by motion picture rental companies that have modified them for film shoots, not from your local hardware store.

I shot a low-budget feature last summer where we carried a Honda 6500w generator to power our "big gun", a 2.5K HMI for day interiors. When transferring the footage later in telecine, I noticed there are a number of scenes that have flicker from the HMI, which we're stuck with because we can't reshoot. It could be due to poorly run cables, but it's also playing with fire to use a generator without crystal synch. I should mention that we did have a flicker-free ballast, which shows that it can happen with those as well.


" It could be due to poorly run cables" I didn't know that this could cause flicker. How can
the way cables are run have this effect? Thanks.
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#17 Jim Feldspar

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Posted 03 June 2007 - 10:53 AM

If a may make a suggestion ... you may want to approach it from another point a view. Call it a shoe string budget idea. You may be able to find 1k pars or par cans much more affordable. In fact you may find you can get a whole cartful or pars for the same price of an HMI. Since it is a night shoot you can kind of "paint" with them and hit areas that are important and let othe areas go dark instead of hitting a whole area with one light.

If you use several pars from the same general area it will look like one light.

And you have the option of using 1200 watt firestarters for punch and heat, or you can easily use 1k wides, narrows or mediums for wider spreads and less intensity. Be sure to get scrims too.

Generally speaking many people don't use HMI's at night. They can be troublesome with headers and ballasts and micro switches and the like. Sure you can and people do, but tungsten is usually cheaper and easier.

Another idea when renting: You can tell them it is for a shoot on a Monday and you need to pick em up on friday and return on Tuesday. So then you get 4 days for the price of one. Or tell them you need it for the week and they may give you a one or two day rate then pick up on a friday and return the following monday.

Good luck

Tim



How do you use par cans on location? I picked up three Altman lights of varying lengths
that had been hung by pipe clamps in a theater. I've used stand adaptors on 1K Fresnels
that have flat yokes becasue they were hanging in a studio but the Altmans are longer
and I think might be front heavy. They have shutters to control the countors of the light
but are I believe par cans or maybe they'd be ellipsoidal spotlights as I've seen par cans
that have no adjustablity. In any event, these lights have flat yokes but if I used them
would I have to bag the heck out of a baby stand or would I need to get a different
adaptor and move up to a junior or combo stand? Thanks.
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#18 timHealy

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Posted 03 June 2007 - 03:39 PM

How do you use par cans on location? I picked up three Altman lights of varying lengths
that had been hung by pipe clamps in a theater. I've used stand adaptors on 1K Fresnels
that have flat yokes becasue they were hanging in a studio but the Altmans are longer
and I think might be front heavy. They have shutters to control the countors of the light
but are I believe par cans or maybe they'd be ellipsoidal spotlights as I've seen par cans
that have no adjustablity. In any event, these lights have flat yokes but if I used them
would I have to bag the heck out of a baby stand or would I need to get a different
adaptor and move up to a junior or combo stand? Thanks.


One uses Pars like cany other light with one or two minor differences. Specifically I am talking about Mole Pars or Par Cans like in rock and roll shows. They both use PAR 64 type bulbs. Most are 1k bulbs that come in wide, medium, narrow, and spot. There is what is called 1200 watt firestarters that are very narrow. There is no flood spot so one changes bulbs to change intensity. The spread of the bulb chnages too. It is the same idea as changing a lense on a HMI par but you don't change the whole bulb on an HMI. Some will mix tungsten par bulbs when they are in Maxi brutes or dino lights.

Back to par cans, all pars (including HMI come with two full doubles and one full single scrims. The half scrims one usually gets with fresnels are dropped. they don't work as well.

If you have a light with a pipe clamp and one wants to use a stand you can change the bail block so it can accept a male 1k stud. Or put a 2k stud on it, or if hanging by a pipe put the pipe clamp back on.

If you have shutters I don't think you have a par can. I think you have a Leko type of light. Thos ehave shutters and iris' and you can put patterns in them.

Best

Tim
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Broadcast Solutions Inc

Rig Wheels Passport

FJS International, LLC

Visual Products

CineLab

Opal

Metropolis Post

Wooden Camera

Media Blackout - Custom Cables and AKS

Glidecam

Gamma Ray Digital Inc

Technodolly

Ritter Battery

Aerial Filmworks

rebotnix Technologies

Abel Cine