Which size hmi lights are in these screenshots?

[starcentral]

Similar to the 2nd photo you posted I recently lit a film using all backlighting or "reverse lighting" through two separate windows and I have to say I really really enjoyed how it looked and also working with this kind of light. I hate to repeat myself entirely since I already wrote about some considerations about shooting with HMI's and reverse lighting so please check out this post if you like: http://www.dvxuser.com/V6/showthrea...ou-use&p=1986331559&viewfull=1#post1986331559 :happy:

As for achieving some of those lighting effects I would say that the strength of light you need really depends on the distance you need to go, if you are passing through actual glass in the window(s) and of course what camera and ISO you will use along with the highest f-stop you will want to shoot with. Even more important is what limits on power you have available to you. For my shoot I could only use two 575w HMI's between a distance of 16-25 feet and shot with an ISO of 3200. Thankfully I was using a camera with low noise. I had little options for power or money for lighting rentals, so that was a factor in my decision too.

If you rent PAR's you should get a box of lenses with it that will help you get a beam angle to maximize the dispersement of your light. We used the barn doors to help block light but for the most part the window itself was cutting the light how we needed. Occasionally we used additional flags or nets inside when we were shooting certain scenes.

I was really going for the "light ray" look you see on Game of Thrones, Citizen Kane or Blade Runner but one caution about a hazer.... its meant to run all the time and not just when you need it to fill a large room. For our location we removed glass from the windows for the lights to come through better which so happen to create a constant draft. Our "haze" spent most of the time being sucked out the windows and in the end I didn't get the effect of the haze like I wanted.

One really great thing about this reverse lighting technique is it sure helps keep lighting off your interior walls! If you don't want such a harsh contrast be prepared to get additional lighting to boost up the ambient a bit, and/or light your walls separately as needed.

Good luck man and be sure to post some frame grabs when you get some.

 

[Hutchman]

Similar to the 2nd photo you posted I recently lit a film using all backlighting or "reverse lighting" through two separate windows and I have to say I really really enjoyed how it looked and also working with this kind of light. I hate to repeat myself entirely since I already wrote about some considerations about shooting with HMI's and reverse lighting so please check out this post if you like: http://www.dvxuser.com/V6/showthrea...ou-use&p=1986331559&viewfull=1#post1986331559 :happy:

As for achieving some of those lighting effects I would say that the strength of light you need really depends on the distance you need to go, if you are passing through actual glass in the window(s) and of course what camera and ISO you will use along with the highest f-stop you will want to shoot with. Even more important is what limits on power you have available to you. For my shoot I could only use two 575w HMI's between a distance of 16-25 feet and shot with an ISO of 3200. Thankfully I was using a camera with low noise. I had little options for power or money for lighting rentals, so that was a factor in my decision too.

If you rent PAR's you should get a box of lenses with it that will help you get a beam angle to maximize the dispersement of your light. We used the barn doors to help block light but for the most part the window itself was cutting the light how we needed. Occasionally we used additional flags or nets inside when we were shooting certain scenes.

I was really going for the "light ray" look you see on Game of Thrones, Citizen Kane or Blade Runner but one caution about a hazer.... its meant to run all the time and not just when you need it to fill a large room. For our location we removed glass from the windows for the lights to come through better which so happen to create a constant draft. Our "haze" spent most of the time being sucked out the windows and in the end I didn't get the effect of the haze like I wanted.

One really great thing about this reverse lighting technique is it sure helps keep lighting off your interior walls! If you don't want such a harsh contrast be prepared to get additional lighting to boost up the ambient a bit, and/or light your walls separately as needed.

Good luck man and be sure to post some frame grabs when you get some.

Thanks again guys, great info posted here!

Dennis, I'm shooting on the Blackmagic cinema camera, it's rated at 800 ASA but performs very nicely at 1600 if lit, and I generally shoot interiors between f4-5.6.

I can vary the aperture to shoot the scenes, my main thing is how much I can fit on a genny, or better still, how much I can run off an Australian house circuit. Since the 2.5kW PAR is the largest easily available to me, I's ideally like to use that if I can. How does shooting through glass compare to not, other than the haze issue?

 

[Hutchman]

Assuming you have light control like all the images posted in the first post a Dedo 400w daylight unit with ballast and 650w globe with projector could get you there. Much less power requirement.

Where in Aus are you located? You'd want to test it of course, but in theory it should do the job.

Thanks Noel, I'm roughly halfway between Brisbane and Sydney, and have access to the 2.5Kw PAR at film school, so travelling 4-5 hours north or south for larger lights is far less desirable.

What's the largest HMI you've been able to run off a household circuit?

 

[starcentral]

How does shooting through glass compare to not, other than the haze issue?

Your welcome.

Before this shoot I did my own tests at home with some tungsten ARRI's and even a Source 4 and a light meter just to see what kind loss I was getting through window glass. I guess naturally I thought light through glass is light through glass and why would it lose any intensity? But it did. The amount you lose will depend on the glass and if its double-pane, etc.. In my case the glass at the location was dull and weathered down from the elements. It cast a yellow dull bla over everything and seemed to act as a diffuser which added fill to my area I didn't want. So I had my crew remove it.

I think if your glass is super clean, modern, and new you will not have the problems I did. But definitely expect for 1-2 stops loss of light.

With light as they say more is better since you can always scrim it, dim it, etc..

 

[paulears]

its meant to run all the time and not just when you need it to fill a large room

Not so. Virtually all hazers have remote controls, and we run them as we need them - having the ability to turn them off is crucial if sound is important, because the compressors are so noisy. It's standard practice to run them up until the saturation is sufficient, then kill them. The cheap hazers have larger and heavier particles so they tend to sink, and these may need more on-time. Once you have haze in the air, and it's not being removed by air con systems, there is no point adding more, and if you do, it can get too dense and start to be visible. Some, but not all, hazers have controls to let you knock down the output - others just are really one switch devices. Some are quieter, some noisy. As you'd expect, the more powerful ones are noisier!

 

[starcentral]

Yes of course you turn them off when you're about to roll (they are pretty noisy) but you also don't just turn them on for a couple minutes for the first time before you shoot either. That's what I meant by needing to continually have it run, but yes definitely "as needed". Sorry my post might have been misleading.

For those thinking of using a fog machine, a good hazer lasts longer than a fog machine because it's less dense but also the effect can be quite different. On camera the two have quite different looks to them. A hazer will allow light rays to show up without otherwise seeing smoke on-screen whereas a fog machine will be much more apparent on camera and depending on the quality of the fogger can be quite patchy as well. A hazer with enough saturation can actually act as fill lighting to the rest of your scene which can be useful as well.

Unfortunately for me, the wind ruined the effect I was going for so perhaps next time!

 

[ilauzirika]

over here in 220v land I have used a 4k alpha with two honda 3000 in parallel mode. And we connect 2,5k hmis in household circuits. But before using in a 2,5k in any 220v household circuit you must check that the breaker for that circuit is a 16/20Amp one, not a 10A one (as in older houses you can still find 10A breakers for wall plug circuits). And keep an eye on any other department, coffee machines, hair-dryers, heaters, fridges....They can kick in and trip the main breaker.

 

[Hutchman]

over here in 220v land I have used a 4k alpha with two honda 3000 in parallel mode. And we connect 2,5k hmis in household circuits. But before using in a 2,5k in any 220v household circuit you must check that the breaker for that circuit is a 16/20Amp one, not a 10A one (as in older houses you can still find 10A breakers for wall plug circuits). And keep an eye on any other department, coffee machines, hair-dryers, heaters, fridges....They can kick in and trip the main breaker.

Interesting to know about the parallel mode on the 3000, thanks!

So I'm assuming I could run a 4K HMI off a 20amp 240V circuit?

I'm still a bit confused about gennys. Guy Holt says if you use a "Power Factor Corrected" HMI, you can use the Honda investor gennys pretty much to capacity; but is there an easy way to know if they are PFC?

 

[ilauzirika]

So I'm assuming I could run a 4K HMI off a 20amp 240V circuit?

I would recommend against running a 4k from a household 20A circuit (or any household circuit, for lots of reasons...), A 4k must be used, at least, in a 25A (220/240v) circuit (which is what the honda 65 provides), preferably an inverter generator or industrial/commercial source(in europe's case a single phase 32A cee conector) , the current required to strike an hmi asks for some headroom. Hence the honda 6500 or two honda 3000s in parallel mode. For small productions we usually carry a 4k alpha 1600alpha, a joker 400 and some smaller units (kinos, dedos,tungsten, etc...). The 4k always goes to a generator (unless a 32amp circuit is prepared exclusively for us) and the rest goes to the household plugs or smaller generators.

 

[Hutchman]

I would recommend against running a 4k from a household 20A circuit (or any household circuit, for lots of reasons...), A 4k must be used, at least, in a 25A (220/240v) circuit (which is what the honda 65 provides), preferably an inverter generator or industrial/commercial source(in europe's case a single phase 32A cee conector) , the current required to strike an hmi asks for some headroom. Hence the honda 6500 or two honda 3000s in parallel mode. For small productions we usually carry a 4k alpha 1600alpha, a joker 400 and some smaller units (kinos, dedos,tungsten, etc...). The 4k always goes to a generator (unless a 32amp circuit is prepared exclusively for us) and the rest goes to the household plugs or smaller generators.

Thanks again, I'll stick with the 2.5 on mains and the 4K on the 6500

 

[RyanT]

Thanks again, I'll stick with the 2.5 on mains and the 4K on the 6500

Really you should be careful doing this, because they're different power sources there is a chance electricity can arc between two lights on different power sources in an attempt to complete the circuit. To avoid this you should run a line (#2 wire is fine for this) from the generator to the grounding rod of the house and bond them together. You can also just make sure you place the units on the secondary power at least 12' away from each other for interiors and 20' away from each other on exteriors. The idea is that the biggest metal object you'll have that could connect the two lamps is 12' and 20' speedrail.

I would much rather play it safe though and just run that line, either way, good info to know.

 

[Moseph]

Interesting to know about the parallel mode on the 3000, thanks!
So I'm assuming I could run a 4K HMI off a 20amp 240V circuit?
I'm still a bit confused about gennys. Guy Holt says if you use a "Power Factor Corrected" HMI, you can use the Honda investor gennys pretty much to capacity; but is there an easy way to know if they are PFC?

If you consciously typed "investor genny" not meaning "inverter genny," you might have a lot more familiarization ahead.
But still, you can't be running a 6k with a PFC ballast on a 6500w genny. Even if the ballast is power factor corrected, there's no way it's only going to draw the number of watts that the light is listed as. A 4k with a PFC ballast will draw at least 40 amps, 4800 watts.
With HMI's, there are too many factors affecting how much power it will draw to say for certain that anything over a 4k will work on a 6500w generator, and even that is pushing it. Only with tungsten lights would I have no problem pushing it to it's capacity (which is actually 5500w).
As for determining if a ballast has PFC or not, just see how much power it's pulling. If it's considerably more than the wattage of the fixture, probably not.

 

[RyanT]

Believe it or not I ran a Arri 6k par a while ago on a 6500w Genny for an hour or two. I didn't think it would work myself, but hey...can't argue with results. Definitely not good for the Genny though.

As far as power factor correction, look on the ballast, it will say what the power factor correction is and if its 1 it's power factor corrected.

 

[Hutchman]

If you consciously typed "investor genny" not meaning "inverter genny," you might have a lot more familiarization ahead.

It was a spellcheck error, I swear! But yes, I certainly will investigate it more. Just didn't want to appear a total noob when I call up the rental houses and ask advice