HMI and Generator - advice and general knowledge

[Maximilian Neumann]

Hello everyone,

 

I'm a final year student and currently in the pre-production and planning for our graduation film.

As a result I'd like to ask a few questions and wanted to generally just check back if my plans or approach to certain scenes/looks seems reasonable.
I'm noticing more and more that my knowledge is limited to our uni's kit room, but beyond that I feel like a baby learning to walk.

 

In terms of this graduation film hat means currently especially the area of HMI and Generator's.

 

I know an HMI omits 5600K daylight light and is about double (?) as bright as a tungsten bulb, that it is Hydro-oxygen haze, based and requires a ballast. In the practical side of it however I am quite lost.

So jumping to the point: For the film there are some scenes that are set in a warehouse-like location both day and night.
It is a large area and for the mood and atmosphere of the film I was aiming for something similar to this:



My plan to approach this was to use an HMI (2.5K or 4K) to shine though the windows and put a large silk (this is basically large diffusion cloth, correct?) in front of it to fill the windows, as well as add a Haze machine.
Then, after getting that ambient light add any lights for characters, either through diffusion or bounce.

For the night I was thinking of the same setup but with a CTO or CTB in front of the HMI.
CTO to simulate orange streetlamp light and CTB to simulate moon light.

So, first of all: Does that seem like a reasonable approach to achieve that?

Now two problems I have:
The location we're looking at doesn't have enough power outlet so we were thinking of hiring a generator.
And, when it comes to that I am quite clueless. I know generators run off petrol, and are very noisy, so our sound recordist would kill me, so I was wondering if there are any noiseless generators? And in which power levels they come? I reckon we'd need between 10-15 Kw.

Problem number two: The location we're currenly looking at is on a 1st floor, so is it even possible to use that HMI safely? Or would have to scrap that plan and light simply from the inside?

I should probably also mention that I'd be looking for a stop of roughly F4.0, at least for the wides.

And while I'm at it: The location warehouse building has several areas, that are not always shown at once but we may move into, all at the same floor all with windows: Is it possible to use the same HMI through different positions (for different shots obviously)?

Any tips or advice would be greatly appreciated and thank you for your time! :-)

All the very best,

 

Max

[Edward Lawrence Conley III]

No problem shooting the HMI light through the windows even at the height you mentioned.

 

Just hire a boom lift or a scissors lift.

 

 

 

The problem is just money :)

[Edward Lawrence Conley III]

http://www.cinematography.com/index.php?showtopic=61818

[Phil Rhodes]

That's going to need bigger things than you've mentioned, I fear.

 

That would be a row of 18Ks in Hollywood.

 

P

[David Mullen ASC]

When you say "1st floor" do you mean the floor above the ground floor or the ground floor?

 

There's no way you (or me for that matter) can afford to light that many windows for daytime -- I'd make a plan of using mostly available daylight. You can have a strong HMI shining through one or two windows as if the sun was coming through a gap between two distant buildings, that explains why it wasn't hitting every window.

 

For night, I wouldn't mix moonlight and streetlight colors, that's just going to look cluttered and in reality, the streetlamps would overpower the moonlight anyway. I'd pick one or the other, probably streetlamps as the source because, like the problem with sunlight, it would be hard to have moonlight coming through every window evenly as if there were one single giant source in the sky. At least with streetlamps, you can justify the light being spottier.

[Maximilian Neumann]

When you say "1st floor" do you mean the floor above the ground floor or the ground floor?

 

There's no way you (or me for that matter) can afford to light that many windows for daytime -- I'd make a plan of using mostly available daylight. You can have a strong HMI shining through one or two windows as if the sun was coming through a gap between two distant buildings, that explains why it wasn't hitting every window.

 

For night, I wouldn't mix moonlight and streetlight colors, that's just going to look cluttered and in reality, the streetlamps would overpower the moonlight anyway. I'd pick one or the other, probably streetlamps as the source because, like the problem with sunlight, it would be hard to have moonlight coming through every window evenly as if there were one single giant source in the sky. At least with streetlamps, you can justify the light being spottier.

 

Thank you very much for your answer!
Yes, I mean the floor above the ground floor which I reckon to be around 3 something meters.

Yeah, I am now actually going for 2x2.5's through 12x12 half-silks through windows to create light areas in which the talent can move and use CTB's geled tungsten fresnels to light the actors, leaving the rest in the dark so that it's just those two patches, like sun or streetlight.

Not to mix the colours is a good advice, thank you! Do you think a 'regular'maybe 1/2 CTO in front of the HMI's give off that strong orange streetlight- light?


Edward Lawrence Conley III:
Thank you very much for the link!
After a visit at a local hire company it seems we'll actually be going for 2x 6K generators (Honda EU6500IS), as they and the lamps form a deal for us.

And we're currently also looking into possible scaffolding platforms for the lights, though beforehand measure he exact height. The stands we got seem to go up to 3.5 meters, and I estimate the height of this first floor to be around the same.

Again: Thank you very much everyone for your answers! :-)

 

 

Edited February 17, 2017 by Maximilian Neumann

[Guy Holt]

I am now actually going for 2x2.5's ....After a visit at a local hire company it seems we'll actually be going for 2x 6K generators (Honda EU6500IS), as they and the lamps form a deal for us.

 

Unless you want your talent to play as silhouettes against the windows, you will likely need the 2.5kw HMIs inside for keying and filling your actors - tungsten heads gelled with CTB will not be enough. Since there are more windows than you could possibly cover with just two 2.5kw HMIs, I would use only available daylight through the windows and push the 2.5s through diffusion frames to key and fill your talent.

 

A new power option, which might be ideal in this situation, is to parallel the two Honda EU6500is. A complete system would consist of two Honda EU6500s (or modified EU7000s) and a Paralleling Control Box. The paralleling box will give you a combined output of 120A at 240V(60A/leg), which is enough to run up to a 12kw HMI – so you will certainly be able to run your package consisting of two 2.5k HMI and have power left over for smaller HMIs and Kinos.

 

 

(Our 120A Paralleling Control Box combining the output of two modified Honda EU6500s to power a Mole 12/18K Par head with 12kw globe)

 

The Paralleling Control Box syncs the frequency and equalizes the load between the generators. It uses the Pulse Width Modulation (PWM) and droop voltage regulation of the generator's microprocessors to control the load sharing. The phase angles of the two generators are synchronized using open loop architecture. The final function of the paralleling control box is to switch the outputs of the inverters to a common bus after their frequencies are locked in step (same phase angle and time base.) Use this link for more details about paralleling Honda EU6500s and EU7000s.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston