I am doing a promotional video for three schools for deaf children in Jamaica soon. I am fairly new to HD and am studying lighting trying to climb the learning curve, so bear with me here.
I spoke with a local representative here in the States about the lighting in the class rooms. He couldnt remember what kind of bulbs, but stated the lighting was poor. The classrooms do have windows, just how much sunlight comes in, I dont have a clue.
I am thinking I will need a lot of hard light and got looking at the pricing of pro lighting and decided I would rather donate that money to the schools for books, medicine, etc (which I normally do at these places)....so went down the DIY route.
I thought I should have the abililty to do 5500K lighting to augment the sun coming through the windows and also the interior lighting, so I built a frame to hang a sheet of CTB. In testing the thing out however, the 110U reads only 5200K.

Is 5200K close enough?

Am I going down the right path on this lighting situation?

thanks,
Jon
www.row.org

BTW...if you ever want get out of the usual vacation,to go on a adventure "with a purpose", and volunteer your video or editing skills, give me a shout. I am normally in the jungle and places where you are not stumbling over tourists.

Hey Jon, that sounds really cool.

I can't really commit on any of this, due to never messing around with lighting really. However, I have heard that Halogens work great for what you are doing...

I hope that everything works out for you! Thanks for posting the pics of your setup. I think I am going to make one of these myself...

Best of luck to you, and nice site!
~Gabriel

If you can get a mirror reflector, put it outside and aim it into the back of the room. Blast it at a white surface, preferable a positionable white reflector, and you will get a 10,000W daylight-balanced softbox for cheap. You would be amazed at the light from a 36" mirror. This might need help from a crewmember to keep the mirror tracking onto your white surface, but it would solve most of your lighting problem.

Otherwise, 5200K should be fine. I think it's better to be off in a lower Kelvin rating than to go too high. 6500K looks horrible. 5000K just gives skin a slight warm look that may even be preferable. Just don't underestimate how much light you need to fight the sun. For an area the size of a classroom, you will need hundreds of watts of fluorescent. That's not hundreds of "equivalent" watts. You will need dozens of compact fluorescent bulbs unless you gel your windows with ND 1.2 (4 f-stop neutral density).

You might want to reconsider using tungsten with CTB. Unless they have better electrical standards than the U.S., you won't be able to get enough light for the amperage available. So much is lost into the CTB that you would need probably 4-5K of light and there are few buildings that will do that easily.

I like the reflector idea. I have one and will get another. I will be alone so will get stands and holders. I believe I can accomplish what I want on interior shots by properly illuminating a portion of the room.
Your comment on the CTB sucking up light was noted the first time I tried my system out. I must have missed that chapter when reading about CTB's. The 500 x2 lamps dropped significantly with the CTB.
Thanks for your comments Marcus.

You lose less light gelling down than up. I think Marcus had the best suggestion here with the reflector into the back of the room. Talk about inexpensive...

Don't forget that I said mirror. I think only a mirror will have the reflectivity and the stable beam of light that can be aimed at a diffuser far away. I have actually done this and the only real problem was that I had a distant ocean background. There were local clouds that killed the light while the background was still sunny. If your location has a background close to your mirror, the mirror will lose strength at the same rate as the background light. This self-regulating feature is normally going to be a benefit. Still, bring some daylight-balanced light for moments there might be some clouds. In fact, bring everything you can. I rented a mirror reflector from the local lighting rental house and it made things easy. It could be held securely and positioned very easily. We gelled the windows with ND, but we had a very challenging shot with ocean and sky in the background. Trees and grass won't be so bright if that is your background.

Yes true. A reflector wouldn't give you hardly anything. Basically what you need is a mirror on a yoke with easy mounting to a stand. Sand bags will be indispensible too on a windy day!

Sandbags! Of course, use sandbags. I should not have omitted how heavy a mirror is and it's made of GLASS. At a school, there will be kids monkeying around outside.

I can imagine a medium-sized consumer mirror in a frame being set up on a table with a tilted support. I suggest a mirror because it is a common household item and someone at the location should be able to scrounge one from somewhere. You might also be able to use a reflective mylar "emergency blanket" glued to a board. Those aren't as flat as a mirror, but they are very reflective. Aluminum foil may also work if glued to a big board with contact cement. It won't be as direct, but it might work if the foil isn't crinkled too much. The mylar blanket may or may not stay flattened like the aluminum foil. They are cheap, so try both. A little testing will go a long way in this scenario.

Somewhere recently I saw mentioned something about reflective acrylic too. Not sure of the cost (acrylic can be very expensive) but the weight would certainly be better than a standard mirror). Another (great) possibility IMHO is the mirror aluminum like we use on our cool lights reflectors from Alanod in Germany. They sell sheets in the USA from different outlets. You should be able to find them by searching for "Alanod Miro". Miro being the brand name of the highly polished mirrored aluminum. I think this stuff would make a spectacular, super light mirror. It's just a question of coming up with a yoked, lightweight frame. Perhaps something like a piece of Miro attached to foam core (you can't use a sheet of this stuff by itself because it's too thin) for instance and then one of those grip foam core clamps attached to hold it up. Can you imagine a lighter mirror setup? Almost sounds like a great product doesn't it?

That does sound appealing. A very thin product could even be warped slightly to focus or spread the light. I don't know how big one of these could be for shipment, but something along the lines of 36" should work and would be very powerful. Collapsible reflectors can be very handy, but they blow around quite easily. The polished aluminum would be almost as reflective as a mirror, much lighter, and safer. If it was put on something like 1/8" plywood and given a yoke, it would be sturdy and some sandbags would keep it from blowing over.

The rough figure for a sail is one pound of force per square foot at 15mph winds. A 36" reflector would develop about 9 pounds of force in a good breeze. If it is strong and weighted down, it should be safer than having a glass mirror up in the air.

1/8" plywood is a much more sturdy idea then foam core--you're right and you do need a little weight probably or it would really tend to fly. If you want to warp it though you would need something like corrugated plastic on the back which would be a more bendable but not breakable solution.

What do you think would happen if you punched a pattern of small holes in it to relieve it from the wind drag effect. Would the collection of holes influence the light and make it unsuitable for video work? Probably but I'm not certain because the light is coming from in front of it and reflecting off of it. If coming from behind you would see a pinhole effect--but would you see the pinhole effect if you had the sun reflecting off the front of it? I've never seen a mirror like this so I'm having a hard time imagining what would happen. If it was still smooth light output then I think it solves the problem of wind drag...

Hi Jon,

when you have a moment, I would like to dialog with you about ROW and what you do for them.

I couldn't find an e-mail address for you, so please contact me at lancespratt@gmail.com when you have a moment.

Thanks!


Lance Spratt

I'm not sure of the effect of holes on the wind drag, but I don't think it would be a problem for the quality of light. I don't think anyone would ever want to use this directly, so it doesn't matter the pattern it makes on the bounce reflector. Putting a mirror of the sun in someone's face is not doable. This will always be a bounced light.

I know that construction sites always cut a hole in the tarpaper they use to surround the site for dust control. Umbrellas now sometimes have a pressure relief flap at the top to prevent them from becoming inverted. Perhaps a single hole in the middle would help?

Putting a mirror of the sun in someone's face is not doable. This will always be a bounced light.

Yes! Please don't try this at home ;-)

Thanks guys for the discussion on this situation. Logistically hauling mirrors down there is not going to be an option. Going to be in four places in six days scattered around the island, so have to travel relatively light. Two Pelican 1610's wih wheels. Going to check on availability of renting some lights, maybe since this a non-profit organization and project, I can get a no charge or discount.
back to the drawing boards.....

You might want to consider the "space blanket" approach. The thin mylar ones are cheap enough to be considered expendable, and they are super light and transportable. Mounted on something with a little stiffness, they make credible mirrors. You'll want silver to avoid color shifting. I like the spray mounting adhesive that artists use, but in a pinch, you can use grip clips (aka pony clamp) to mount the mylar to your plywood, foam core, cardboard, etc. Whatever you can find on site. Support and aiming may be a challenge travelling as light as you are, but there are options there as well like the mini-grip kits.

Have fun and good luck!

"Logistically hauling mirrors down there is not going to be an option. Going to be in four places in six days scattered around the island, so have to travel relatively light."

I didn't realize you would be in multiple locations. I figured that if you were in one location that they would be able to help you out. Arranging multiple sites to provide you with supplies is not realistic. I don't know what you can do to get a solid backing for mylar foil, but thin plywood should be available almost anywhere and can usually be cut to specifications. Once you are there, maybe you can scrounge the backing and carry it in your vehicle. I wish I could say that collapsible reflectors would work since they are easy to transport, but I have doubts since they have a fair amount of diffusion to their spread.