Daylight Matched Lighting for Indoor Scenes

[Stuart Graham]

Hi

I'm going to be filming a few scenes in a large atrium area during daylight hours. Unfortunately it's a bit dim in the atrium and not bright enough to get good footage of my actors.

Ideally I would use some artificial lights to brighten things up. Since we're in the shade, indoors, I'm guessing the color temperature of the light coming through the windows is going to be around 7000 - 8000K?

There's no chance of sealing off the windows to prevent light contamination as the windows are very numerous and in an extremely high ceiling. I noticed that standard cheap 'daylight' balanced continuous fluorescent lights are around 5000K:

Interfit INT103 - 3 Lamp Cool - Light Head with 3 Bulbs

I imagine using 5000K lights could give a nasty color balance issue with the background looking blue and the subjects the correct colour.

What type of lighting should we use for this situation?

We don't have much to spend and can't afford anything expensive. There aren't any rental places nearby either.

Thanks!

[Bill Pryor]

All daylight light sources are 5200K-5600K. The incoming daylight won't be much different from that, unless there's some tinted glass involved. At 5000K for your key, the backgrounds could be a little blue, but probably not really noticeable.

That light is not going to do a lot for you. It's only a total of about 75 watts of fluorescent. If you're doing closeup interviews, they might be OK. If your budget permits, you might consider trying to rent some HMIs. Or even use tungsten lights with CTB gels. There are four ways to get daylight output--HMI, daylight fluorescent, daylight LED, and CTB gel over 3200K lights.

I have three 500LED daylight lights from flolight.com. Each one puts out about the same amount of light as a 2-bulb Lowel Caselight or Kino-Flo fluorescent, but with just a bit more throw and a slightly less diffused beam. I use diffusion gel for closeup interviews. These are good in dark areas or average room light, but if there's good daylight coming in, you probably are going to need HMIs or at least 1K tungsten lights (gelled) to do anything useful.

If there's no rental house nearby and cost is an issue, are there any other people in your area who might own lights and rent to you cheaply?

One thing you can try is to buy a 24 watt fluorescent bulb and put it in a lamp at home and that way you can perhaps judge how much light 3 of them will put out. If it's good for what you need to do, then you're OK; but in most cases you probably will want something bigger. You might also check the fluorescent softbox at coollights.biz. It uses a single 200 or 250 watt fluorescent, which would be lots more than your three 24 watt bulbs. There may be something similar available where you live. Another company that sells cheap fluorescents with bigger bulbs is Steve Kaeser Backgrounds & Accessories. As a U.S. company, that probably wouldn't work for you, but again, perhaps there's something similar in your area.

[Stuart Graham]

Thanks for the help Bill, it's much appreciated :)

We do have four 500W 3200K tungsten lights - cheap Interfit INT100 ones. It says in the instructions not to put gels over them though, and they do get very hot - one of ours melted inside once when we had the barn doors partly closed. Do you think it possible to put gels over them in some way without overheating the lights?

What do you think to this set of lights...?

2 Light Studio Lighting Quad 40w 4 bulbs Continuous on eBay (end time 19-Aug-09 17:11:09 BST)

They've got a bit more power.

I also found the following adaptors which allow you to screw 4 bulbs into one socket. I could possibly screw these into my Interfit lights then screw 4 powerful fluorescent bulbs into each.. It sounds a bit dodgy though, something might go bang. Any idea if these things are safe?

http://www.smick.co.uk/sonline/4-way.../prod_443.html

Been looking around for a hire company on the web, but haven't had much luck there unfortunately. They tend to be in London and we're based in northern England.

[Jack Walker]

I was just at Lowe's and they have 6500 48" fluorescent tubes (90-100 CRI) T-12 size (regular)_that cost less than $20 for a case. (I think there are twelve in a case, but maybe more.)

They have 2-light 48" fixtures with side fins to protect the lamps for just under $10 each. Low-cost four-light fixtures are also available.

You can rope or chains to hang them from stands or overhead (nails or whatever).

Lowe's also sells plastic protective covers for about $3-4 each. These would protect against slight bumps while working.

--But I now see you are in the UK. The 6500 low-cost high CRI tubes may be available there, too, though.

I think these might work out well for your purpose.

[Andrew Dean]

Originally Posted by Stuart Graham

Thanks for the help Bill, it's much appreciated :)

We do have four 500W 3200K tungsten lights - cheap Interfit INT100 ones. It says in the instructions not to put gels over them though, and they do get very hot - one of ours melted inside once when we had the barn doors partly closed. Do you think it possible to put gels over them in some way without overheating the lights?

sounds like a run of the mill "work light". You can ctb gel them, but instead of clipping the gel close to the bulb, if you use a larger piece of gel a foot or so away from the bulb, like on its own stand, then you should be fine. Pretty much any light can be gelled... you just need to use bigger gels further away.

Something people often overlook with color temp is that it is not a linear scale. The difference between 5000 and 7000k is far less dramatic than from 3200 to 5000k. Various colors of daylight bulbs (5000-6200) can often mix together seamlessly.

Unless you are shooting all closeups, i'm not sure what good the fluoro screw bulbs will do you. An "atrium" sounds like a big space to try to fill with small soft lights. At that point I'd be far more inclined to bounce your tungstens full blast off the walls/ceiling and raise the light level to the point where the indirect light from outside is moot. (my $.02, which might be worth just that)

[Stuart Graham]

Thanks for the ideas guys!

Jack:

Didn't realise the colour temp scale isn't linear. The fluorescents should be fine for our film. I'll see if I can find these low cost fluorescent high CRI tubes in the UK.
What is CRI by the way?
Are these types of fluorescent tubes colour balanced?
Is Lowes a hardware store?

Andrew:

Do you know what sort of stand you would use to support a gel?
The lights we have are studio lights, but about the cheapest money can buy. And they have incandescent bulbs that get bloody hot!
Good idea to try and swamp the area in tungsten light, that might just work :)

[Bill Pryor]

If the lights have barn doors and you clip the gels out to the ends of the barn doors, the gel shouldn't melt. I Gel 1,000 watt lights all the time. Make sure you're using good gels, like Lee. Don't wrap the gel all the way back to the back of the barn door, just clip it out close to the leading edge. I use four C-47s to clip the top and bottom on each side, and let the gel hang loosely as far away from the light as possible. If you buy pre-cut gels, they come in about 24" by 24" sizes (about 60 cm by 60 cm), so there it's easy to let them sag away from the light. Spread the barn doors wide but not so wide they pull the gel in closer.

[Stuart Graham]

Thanks for the great advice Bill. We have two sets of barn doors for our lights already . I'll see if I can buy some gels and clip them on. That will save us a pretty penny!

I'll get two more barn doors for our other lights so we can use those too. I think 4 x 500W lights should give us a fair bit of extra light.

I found a guide to the Lee gels and I think I need to buy some half and full CTB gels and experiment to see which looks best on location in the atrium.

Lee 201 Full CTB : Tungsten to Daylight 3200K – 5700K
Lee 202 Half CTB : Tungsten to Daylight 3200K – 4300 K
Lee 203 Quarter CTB : Tungsten to Daylight 3200K – 3600K

Thanks again!

[Les Howarth]

Stuart you are correct about the colour temperature of UK cloudy or indirect/diffuse daylight it can easily be 7-8k. Sunny days will be closer to the optimum balance of typical daylight camera presets and sources.

You could try testing various strengths of CTB over a daylight source and seeing if this "blues it up" sufficiently.

If the blue is noticeable enough you could also use selective colour correction in post to tweak it. It depend on the effect and whether you want to emphasise that is warmer/safer inside vs colder/more hostile outside - as you might do for dramatic purposes.

[Stuart Graham]

Thanks Les.

I might try and light the atrium slightly bluer to make the scene seem colder. I guess it partly depends on the weather on the day, have to wait and see, were in the UK so it's likely to be cloudy. If it is cloudy I'll put more CTB on to try and correct the light more.

[Shaun Roemich]

Originally Posted by Stuart Graham

I think 4 x 500W lights should give us a fair bit of extra light.

Keep in mind that a full CTB typically has a transmission factor of about 25% so your 4 500watt lights effective just became ONE. Not saying this won't be enough but be aware that colour correcting tungsten becomes an exercise in futility very rapidly when try to compete with that brutal taskmaster, the Sun.

[Stuart Graham]

Thanks Shaun. The sun is awkward isn't it. The fact that the sun's relative position is going to move is a real pain. I'm thinking a cloudy day will be better since:

1. The sunlight will be more diffuse so the sun's relative position will have less of an effect.
2. The sunlight won't be as bright, so our tungsten lights will be more effective.

I reckon I might delay the atrium shoot until we have a bright but overcast day.

What's the transmittance factor on half CTB gel?

[Shaun Roemich]

Half CTB are usually around 40 - 50% transmittance.

[Shaun Roemich]

http://www.rosco.com/includes/techno...erFacts_06.pdf

Page 9 is your friend.

[Stuart Graham]

Thanks for the info and the link Shaun :)