Home-made dimming?

[Kurt]

Okay, so I've been roped into doing lighting for an independent film. I've never lit film before (I've done plenty of theatrical productions) and I'm presuming I'm going to need some sort of portable lighting, which I can absolutely locate and rig, but I'm concerned about any dimming I may need to do.

I'm an undergrad, so I'm certain I can get access to some instruments that are collecting dust, and wherever we may end up shooting I'm sure I can find power, but I'd really love to be able to dim my instruments.

We don't have any portable dimmer packs and I'm certain I can't get my hands on a console as they're always in use, so I had thought to perhaps make a sort of home-made console for a few lights.

My theoretical design entails some basic dimmer switches, and some basic inputs and outputs.

Problem being that the dimmer switches one could get at home depot for cheap have a wattage max of about 600 watts. That's fine if I assume I'm not using any instruments over 600 watts, but that may not be possible.
My other thought was to see if barbizon sells any high wattage dimmer switches, and they do, but they're fairly expensive relative to the home depot switches.

So my question is, what's the cheapest way for me to build a system that can dim a few lights? The film is fairly low budget... in fact it's probably whatever we can scrounge up plus whatever we are personally willing to put in. If I have to pay for my system out of pocket, I'd like for that system to be as cheap as is possible.

 

[TDN]

Places like McMaster-Carr have thousand watt dimmers, if you want to go down the build your own route.

This may not be feasible, but depending on your instruments, rather than dim, could you have a variety of lamps and some neutral density gel? Gel is a lot cheaper than building dimmers.

For film, you will generally compose a look for each shot, so there is less of a need for dimming instruments, just move them further away, bounce off or through a sheet, change out bulbs, etc. Small clip on lights from Home Depot and 40, 60, 100 watt bulbs will be your friend. But most of my experience of film sets is there isn't really dimming, just swapping out and adjusting the instruments to get the look.

 

[techieman33]

If your filming over a short timespan I would go the rental route, over building your own. And as TDN said, you probably won't really need much in the way of dimming. And the school might be willing to let you borrow some ND, CTO, CTB, etc.

 

[tdrga]

Most film lighting uses lighting modifiers for incandescent sources (gel or screens in front of the light to cut intensity) rather than dimming to avoid the color shift that occurs as the lamps are dimmed. A mixture of color temperatures in a shot is nightmare to fix so it looks "right." Your need for dimmers may not be as great as you expect. If you have time, you might try experimenting with some lights and the type of camera that is going to be used to get a feel for how much light is needed.

-Todd

 

[Kurt]

That's not a bad idea. The university does have a pretty solid stock of gel, including some ND floating around somewhere. And I'm pretty sure I've seen those clip-on lights hanging around our instrument storage. I've only seen a couple but it's entirely possible we may have a box full of them somewhere.

I do like the idea of using different lamp types, but I'm not entirely certain we've got a fantastic stock of different lamp types, at least when it comes to fresnels and scoops. I may have to dig around there a little more and see what we've got.

I'm not sure yet about timespan. It's early in the process right now, but I'd like to get everything I need together so when we start filming I'm not scrambling to figure it out

 

[Les]

Yeah, location lighting usually uses scrims and other media as lighting control. But failing that, I would just hop on eBay and shop around for used portable variacs. Some can be pricey, but there are a few good deals out there.

 

[porkchop]

I'd look into rental packages. Lock down filming to a short period of time (a day or two). Rig it in the morning before day one and tear it down before you leave the evening of the last day. Should be fairly reasonably priced and will be much safer than any home-brew setup.

 

[JonCarter]

Having worked in industrial film and TV commercial work for a number of years, I can tell you that I've never found a need for dimmers, either in studio or on location. Dimmers might be useful when shooting B&W, but there are other ways to vary intensity. If it's too hot, back the lamp off a few feet or flood it a bit. If you need to diffuse it, use a screen or a silk. Dimmers when shooting color just cause color temp problems. If reflectors won't cut it and you're using inky or arc fills in daylight, filter the inkies to 5400K and use white flame carbons. If you're shooting indoors use 3200K lamps and yellow flame carbons. Keep everything at the right color temp for the film in use.

 

[Catwalker]

At our theatre, we have a couple domestic-style dimmer switches rated for 1500 watts. I'm not sure where they came from, because we've had them for ages.
The idea of using gels to cut intensity sounds like the most sensible option, although I have rather limited experience working with any sort of film.

Someone who works at our theatre told me that he once had to use jars full of saline solution, with two electrodes dipped in, adjusting the electrodes to achieve dimming....
(yes, bad sentence, I know, but everyone has slip-ups...)

 

[stephen.plotkin.1]

If you are actually using film you will probably not want to dim the lights as you will change the color temperature. Scrims and neutral density filters are what you want.
If it is video you must do a white balance in the mixed light or you will have issues. As most film is lit from the floor you can vary the intensity by moving the fixtures closer or farther away from the scene or spotting and flooding them if they are fresnels or open face been lights.


Sent from my iPhone using Tapatalk

 

[derekleffew]

... I've never lit film before ... but I'd really love to be able to dim my instruments. ...

As others have said, (electrically) dimming light sources for film or video is usually not desired nor recommended. For a description of available color media, see the wiki entry neutral density filter.

... So my question is, what's the cheapest way for me to build a system that can dim a few lights? ...

1. Type "variac" into eBay or other vendor
2. Buy a single channel electronic dimmer rated for >= 1000W: http://www.filmtools.com/10watrotdial.html , http://www.lexproducts.com/products/entertainment/power-control-solutions/portable/slim-dimmer-1800w
3. Buy a Pocket Console (or similar), a DMX512 cable, and a shoebox dimmer

Buying a hardware store dimmer, even if appropriately rated, is out. These are UL-listed only for in-wall permanent installation, not for portable use.

...I'm not sure yet about timespan. It's early in the process right now, but I'd like to get everything I need together so when we start filming I'm not scrambling to figure it out.

Unsolicited advice: Peruse a copy of Harry C. Box's Set Lighting Technician's Handbook, either from your local library or favorite bookseller. The sooner the better. Come back here with your (inevitable) questions.

 

[JD]

Just in case no one posted this, REMEMBER, as soon as you dim a lamp (other than gel/mechanical) the color temperature is no longer correct. This really shows up on film. Standard lamps such as incandescent and halogen will take a wicked twist to the orange and plummet in color temperature.

 

[Kurt]

Unsolicited advice: Peruse a copy of Harry C. Box's Set Lighting Technician's Handbook, either from your local library or favorite bookseller. The sooner the better. Come back here with your (inevitable) questions.

I'm ordering a copy now. Some reading will definitely be helpful as I'm sure I'll start to run into things that I don't know how to fix *yet*. Thank you for the reference.

I'm definitely going to have to start digging through gel storage and see what all we have buried. Considering we have a decent stock of R00 I imagine we have a good quantity of some of the gels mentioned.

 

[Jay Ashworth]

Note that the color temp issue is still the case even when shooting on video, they at least need to all be the same, or close enough, unless you're lighting for effect; you're going to want a color temp meter, though if your smartphone is smartenough, a colortemp metering app may be Good Enough for you.