building a softbox

[powerdog]

I'm using a great book on DIY video equipment to build a softbox. Author has it configured as a narrow, vertical light, with 6 bulbs mounted on a board about 6 inches by 4 ft.

My question is, for mostly interior interviews, would it make more sense to configure it as a square, maybe 3 ft each side, and position the lights accordingly.

[J_Barnes]

What is the material of the softbox? Is it fabric or is it more like a batton box?

[powerdog]

Back is wood with 6 ceramic light sockets. His sides are cardboard mounted on PVC frames, which are mounted to the back with metal brackets. Mine are going to be made from flat ventilation duct panels (thicker than flashing). Either way, front is wider than back, and side panels are held apart with some sort of spacer. Front material could be anything white: cotton sheet, silk, etc.

Question is, long and narrow, or square softbox for seated interviews?

[J_Barnes]

Yes, this is what they used to call a Batton box. They used to make them out of cardboard file boxes with a piece of 216 taped to the front and a baby nail on attached to the back for mounting.

I would assume that if you're doing seated interviews...chest up or any thing "talking head" ish...then a square would be more useful. It sounds cheap enough to build to though, right? Maybe you might want to build two.

Are you using photofloods in the box, or some other household bulb? Also ,the nice thing about having 6 ceramics is that you can mix and match color temperatures within the batton box, allowing you to warm up a cool light and cool down a warm one alternately.

[powerdog]

I'm using 75w spotlights, as the author says that floods (much more common at Home Depot than spots) would be diffusing the light a second time, in addition to the fabric on the box. He recommends using all the same type on the theory they're easier to white balance. These particular bulbs claim to be "whiter" than other spots -- what that means to video, we'll see.
I've also just finished constructing an all-purpose stand out of PVC that I really like.I'll use it for the softbox, and another for a reflector. A couple of key joints are not cemented together, so it's fairly compact for transport. It also has adjustable height and a crossbar at the top for hanging things.
I agree that square, or less long, is the way to go. I don't need to waste light on people's feet or knees.
Great book, BTW, on DIY video equipment. I mentioned it on this board before, but no one seemed interested.

[J_Barnes]

People aren't interested in paying for stuff very often.

I'm developing a site that will act as a repository of filmmaking articles written by people from the filmmaking community. If you're interested in sharing it, I'd love to host a tutorial about how to build your stand.

[powerdog]

I know money's tight, but I figure one piece of equipment I build instead of buy is going to pay for the book several times over.

I'd be happy to share instructions for the stand. Of all the stuff I've built out of wood or PVC, it's probably the one thing that I didn't regret something about the design or construction!

[Stanrick_Kubley]

Hey, this is a great idea! What you're building will do the same thing, without the cost and should be more flexible than a store-bought softbox. That's really cool; in fact, I think I'd prefer something like that over a standard softbox.
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Question: Is the front of the softbox really necessary? With a wall of lots of little lights, could you get away without the front? The reason I ask is that a typical softbox contains only one naked build, and the inside, baffles, and front are used to spread the light over a wide surface, creating the wall of light.

In fact, couldn't the same thing be built using smaller bulbs (and more of them)? Or a strip light using lots of little bulbs? Just thinking out loud.
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For interviews, or even for closeups in a movie, the purpose of the softbox is usually to create a wrap-around effect, which creates a slower falloff of light as the surface of the head rolls into shadow and also softer shadows. The size depends on how far away the softbox is from the subject. Generally, I'd say you want the biggest you can get, especially horizontally. But a big square would also work. Or you could make a big square and just remove bulbs as needed.

What are you paying for the ceramic sockets? You've inspired me.

[powerdog]

This is definitely a learning experience for me, and if/when I build a 2nd box, I'll want to modify the design.

The softbox consists of a plywood back panel, approx 1 ft. wide by 2 ft. long. I have six sockets in two columns, three rows. The bulbs are 75w spotlights rated for something like 800 lumens, and they're flat on the front with diamond-etched surface (similar to headlights). I think the idea is that you want as much light as possible to get out the front, and regular bulbs would just spread the light inside the box. This way, the box can diffuse as much light as possible. The sides are made out of flat ventilation panel, and the top and bottom out of flashing. I've drilled through the metal to attach panels to the wood back, and I'm using a combination of metal epoxy and machine screws to hold the panels to each other. I also have two lengths of dowels holding the sides apart at top and bottom. (The sides are spread apart so the front is wider than the back.) Last I'll add a hook on the back, and find some relatively sheer white fabric for the front. I can say that the bulbs throw a lot of light forward, so I imagine I'll be able to place the softbox fairly far away from the subject and still get decent illumination.

If I do this again, I would look for some kind of small wooden storage unit with an open side or removable door. That, maybe spray painted silver inside, would give me a sturdier frame and be a lot quicker to build. The one I'm making is going to be somewhat fragile, and I"ll probably carry it around in a cardboard box.

The sockets are about $1.75 each. The biggest expense is the bulbs, at about $7.50 each.

Another thing my book pointed out is that instead of buying bulk wire and other wiring parts, it's easier to buy 6 cheap extension cords, cut off the outlet end, and use those to wire the sockets. They're only about $1.50 each. All six are plugged into a cheap power strip I've mounted on the back.

[J_Barnes]

THat sounds quite heavy...what thickness did you use for the plywood back?

The design I saw used much lighter weight parts, so I'd feel alot more confident hanging it of a C stand arm. You could also wire the sockets in series if you wanted to skip the powerstrip on the back, but you wouldn't be able to switch on and off individual bulbs then.

[Rogue Crew]

Another thing my book pointed out is that instead of buying bulk wire and other wiring parts, it's easier to buy 6 cheap extension cords, cut off the outlet end, and use those to wire the sockets. They're only about $1.50 each. All six are plugged into a cheap power strip I've mounted on the back.

Dawg, this sounds really dicey to me. What you are building is equivalent to a household electrical circuit and should be wired accordingly. At my local Lowes, I can get Southwire-Romex 25' 14-2 NM-B with Ground Indoor Electrical Wire for $6.62, which is way more than you need, but surely cheaper than 6 extension chords. Any electrical supply (including some Lowes and Home Depots) that have sheathed cable on a reel will sell you the couple of feet that you need for the loose change in your pocket.

Inevitably, you or some other builder are gonna say that 75W lamps aren't enough and will try out 100's or 150's and as you describe it, the potential for very unhappy results are there.

[Guest]

<Great book, BTW, on DIY video equipment. I mentioned it on this board before, but no one seemed interested. >

I'd be interested. I bought a book online that I've used to build a dolly, glidecam, and am now working on a crane. I'd love to find one with lighting rigs, since I usually build what I can't afford...which is just about everything but a camera.

[powerdog]

Rogue, I don't see a problem. I've got 6 individually wired sockets, and there's plenty of capacity in the ext. cords for each bulb. They're all plugged into a power strip with circuit breaker. The book writer has used both 75 and 85w bulbs in this way, and not had a problem. I don't plan to go beyond 75, so I think I"m ok.

James, this is the book:
http://www.amazon.com/exec/obidos/tg/detail/-/0240805461/qid=1096912529/sr=8-3/ref=sr_8_xs_ap_i3_xgl14/104-8374749-0129534?v=glance&s=books&n=507846

Note that it doesn't have a lot of lighting stuff. But the breadth of equipment he covers is amazing, especially since all the parts seem to be available at Home Depot.

[J_Barnes]

6 75watt bulbs is 450 watts total, pulling about 3.75 amps. Your wiring seems a little overdone, but it should be able to handle the pull. If you planned on going up to 100 watt bulbs, it'd be wise to wire the sockets in series and use a single 15 amp extention.

Chances are that the housing will catch fire before the wiring does.

[powerdog]

Definitely no plan to go above 75 x 6.