Mar 15, 2008

How many lights can I plug into this circuit?

You're on location, in a house built in the 1940s. But you're worried about blowing fuses or popping a circuit breaker with the bright and hot lights from the nice Arrilite kit you brought.

You need a way to tell in advance, how to know when the next light you plug in will blow the circuit. You're not an electrician, you heard there was a formula, by some Ohm guy, but you have no idea what it is.

No matter -- There is a simple way to figure this out, and keep out of hot water (and in the light) with the homeowner.

It seems confusing, because the electrical draw of your light fixtures is expressed in Watts, while circuit capacity is marked in Amps. Ohm's Law is an electrical formula that electricians use to make this conversion, but in practical application, you don't really need to use a calculator for this sort of simple situation.

Let's start by looking at the situation in the house. A circuit is a single line of electrical supply, that is usually shared by several outlets or lights in the home. Each outlet is NOT a circuit! Instead, multiple outlets are shared by one circuit. Also, normally, all the outlets or lights in a room are not dedicated to a single circuit. They are usually spread across several rooms. In a two story house, the lights will usually be on circuits shared between floors. This seems illogical, until you realize what happens if the circuits were divided by floor. If that circuit blows, all the lights on that floor go out, and no one can see, until they can find the a flashlight, and get to the circuit breaker.

Fortunately, discovering the capacity of a circuit in a home is easy. First, find the circuit breaker panel. (The following refers solely to 120 Volt electrical service as commonly found in North America.) It might be in a utility closet or it might be on the back porch. If the home has a garage, it is often found there. Upon opening the panel, you'll normally find two rows of black switches, the circuit breakers. These have two digit numbers printed on them, normally a a 15 or a 20. That number is the number of Amps the circuit can safe handle, before the breaker trips off, cutting off the power. If the circuit breaker didn't do this, the wiring in the walls would overheat, and start a fire. This is a special effect we normally want to discourage -- and there are better ways to meet firemen.

If the house is older, built before the 1960s, and never been re-wired, it may have fuses. These are very often only 10 amps. NEVER replace a 10 amp fuse with a higher number fuse, this is very unsafe! If you're blowing fuses, it's for a reason. More current is being drawn than the circuit can safely handle without overheating.

The next puzzle is to figure out which outlets in the house are assigned to which circuits. If you're very fortunate, sometime in the past, someone else already figured this out for you, and filled in the blanks in the circuit description on the circuit breaker panel door. Sadly, we often find that we're the first persons to bother filling in this card. If that's the case, you have little choice but to experiment, and turn breakers off and on to determine which plugs they control. Before you start, make sure there is nothing plugged in or turned on that might be harmed by the loss, or sudden resumption of power. Home electronics, computers etc. Now you could have another crew member walk around the house with a light, plugging it in to every outlet, yelling out when the light is extinguished, as you flip breakers in turn. A slightly more elegant solution is to use a cheap AC outlet powered radio instead of a light. That'll preserve your vocal cords. It also works well if you don't have an assistant--although with a lot more steps as you walk back each time to move the radio's plug. But you needed some exercise anyways, right?

You'll notice too that in addition to the breakers marked 15 and 20, there are other breakers, with higher numbers, and ganged together as one switch. You don't need to test those, they're for high power items that are hardwired, or not plugged into standard outlets, such as clothes dryers, ovens and heaters. If you're lucky, all the outlet breakers will be 20 amp circuits, and the 15 amp breakers are just assigned to ceiling lights. As it is, you may discover that all the outlets in the house are assigned to as few as two or three breakers.

Now that you know what outlets are available on each circuit, all that's left is to figure out how many of your lights you can plug in to each circuit, staying safe, and not popping a breaker!

I use this simple rule of thumb-- Each amp is "equal" to 100 watts of 120 volt power. Now this isn't correct-- but this rule of thumb leaves a nice safety factor, as it's not really a good idea to load a circuit all the way up to its maximum amperage limit.

So if you plug in a 600 watt light, that takes up 6 of the amps on a 20 amp circuit. And if you plug in two more 600 watt lights, the total is 1800 watts, or 18 amps; you're still under the limit, and won't pop a breaker. But if you start with a 1000 watt light, you only are safe for one more 600 watt light -- another 600 watt light would be 2200 watts, and that's over 20 amps, using our rule of thumb with a built in safety factor. But you could plug in another 400 watt light. If you need more than this, you should find a stinger (AC extension cable) and move on to the next circuit.

A word of caution-- Always keep an eye open for what else might be plugged into the circuit. They need to be taken into account too. So if there's a computer that needs to be left on, on the circuit you need for a light, you have to accommodate it's load also. If the computer draws 500 watts, and it's a 20 amp circuit, then you only have 1500 watts available on that circuit. I really really recommend against sharing lights and a computer on a circuit though.

Watch out for these appliances, that draw much more power than most people realize: Hair dryers and curlers, laser printers, coffee pots etc. Laser printers are particularly sneaky, as they don't draw much power till they print, then suddenly you will see a 600 watt surge, and your lights go out!

Most all of this applies also to offices and commercial bldgs-- These often have sub breaker panels on individual floors. Be vigilant about not overloading circuits that might be shared among rooms, or down a hall. You don't want to shut down someone's computer when they're trying to meet a deadline! A gotcha you'll find in offices is a coffee pot on the other side of a wall in a break room you don't know about, but is on the same circuit you've plugged a 1000 watt chimera into!

Save Money! Shoot 35mm Film!

One of the great myths of low budget filmmaking is that the cheapest way to make a movie is by using a cheap camera and a smaller film guage, or to shoot on tape.

But it's not always true, if your aim is to create a film to watch in a theater-- This requires getting to a 35 mm print somehow.
Shooting in 35mm may well be the cheapest way to get to a 35mm finish. It has been in my experience with some type of projects.

Don't be fooled by the cost of tape stock vs the cost of film stock. The costs of making a digital intermediate and then a print out to 35mm can be far more than these costs. Just as the cost of making a blow up added greatly to the cost of 16mm origination.

Is this a documentary project or a scripted short? What do you anticipate your shooting ratio to be? If it's not a documentary, and you're going to have a reasonable ratio, say 7 to one or less, then you may be better off shooting 35mm

A lot depends on the local situation there for renting cameras and buying film. Here in the US, rental facilities always have older cameras, such as an Arri BL2 or BLIII sitting on a shelf, or if you don't need sync dialog sound, Arri IICs. In Italy I'll bet you can find great deals on Cameflexes. People starting out often turn up their noses at "Old" cameras, forgetting all the great films that were shot in the 70s and 80s with these "old" cameras.

Also, here we can get "Short Ends" and "Re-Cans" which are film cans left over from productions, and there are places that specialize in selling that here. It's not difficult to get 400' rolls that are much cheaper than new. The film is snip tested before they sell it to you.

The 35mm film/processing/workprint/neg cut process is very simple and well understood. You could even avoid expensive tape transfers for Non Linear editing, and cut on a flat bed. People are giving away flat bed editors. They take up a lot of space and there aren't many buyers, they'd rather see someone using it then send it to the recycling center.

Several years ago I was DP (and AC, and Loader for much of the shoot!) on a small low budget film, "FLOSS". I convinced the producer, that since he was in this to make a movie that could be shown in a theater, the best and easiest, and even cheapest route to go was 35mm origination.

Then we used the same techniques low budget film producers have used for decades-- getting bargains, getting people to work for little or no money, and as much for free as possible. Because it's the labor and all the other expenses that constitute most of the budget of the film, not the film stock.

Still when you are operating on this level, there are hard costs you usually can't avoid, namely film stock and processing, and camera rental (unless your DP is coming with his own lesson.)

We scheduled our shoot to start right after christmas, when most TV Series and movies are on breaks. This enabled us to get a great deal on a 35mm camera package from a hollywood camera rental facility. A 35mm Arri BLII with 5 lenses, batteries, 4 mags, Video tap, matte box, everything, for $4900 for 3 weeks!

Sure, the BLII is an old camera. But a heck of a lot of great films were shot in the late seventies early eighties with BLII's, right?

Next up, Film. We bought short ends from Dr Raw Stock in Los Angeles. Here was another example of how shooting in 35mm has advantages over 16mm. By choosing a stock that was popular with multi camera sitcoms, we were able to easily get all the 400' "short ends" we needed. The reason for this is that the multicamera film shows change loads when they get below 500' of film in their 1000 and 2000' loads. Whereas it is not nearly as easy to find a short end of 400' of 16mm, since 400' is the largest load almost everyone ever shoots with.

In all, our stock and processing costs were under $35k. We kept to a low shooting ratio as we knew our actors really werent' going to get that much better after 3 takes. We did more rehearsals, instead of the popular fad for rehearsing on film.

Lighting was a lot easier on Floss, because we weren't shooting on Digital Video. (Low cost HD cameras were still a few years away, the Sony CineAlta HDCAM would have blown Floss's shooting budget in 3 days. We basically lit from a couple of kits, with a 1k chimera as our key light, usually no fill light at all, and some accent lighting. To our eye, the scenes looked to contrasty to someone used to shooting on video, but the bounce from the walls provided nearly all the shadow fill we needed in most scenes.

This enabled us to move very fast and quick, yet looked great for a drama like Floss. In some scenes, such as a torture scene in a warehouse, we used a single hard key. But mostly it was just the chimera, and some rim light, and background lights. Locations were picked for their ability to look good with minimal lighting. We were able to paint the Dental Office so that it wouldn't have blinding white walls, as is typical. Then we used a large house for all the home scenes that gave us several different looks, and also had a lot of wood paneling, which looks good with minimal lighting effort.

Just putting an idea in your head. If you have to shoot a lot of footage, then this won't work. But people assume that digital is always cheaper, and yet make that conclusion without running the numbers on a spreadsheet, using real world quotes of what you can find great equipment for.

Mar 8, 2008


The primary colors of light are different from the ones for Paint and Ink.

They are:
Blue, Green and Red.
Their complementary colors are
Yellow, Magenta and Cyan.

Primary Colors: _ Complementary Colors"

BLUE ________ yellow (GREEN+RED)

GREEN _______ magenta (BLUE+RED)

RED ________ cyan (BLUE+GREEN)

  1. A filter transmits its own color.
  2. A filter absorbs its complementary color.
  3. A filter of a complementary color transmits its two adjacent primaraies, and absorbs its complementary primary color.
For Black and White photography:
  1. To lighten a color, use a filter of the same color.
  2. To darken a color, use a filter of the complementary color.

Behaviour of light through filters:
  • Transmittance- Light allowed to pass through the filter (A red filter passes red)
  • Absorption - Light absorbed by the filter (A UV filter absorbs UV)
  • Refraction - Bending of light passing through glass to air or glass to glass. Diopters, Prisms
  • Diffraction- Bending of light passing sharp opaque edge. (Star filters)
  • Diffusion - Breaking up of light rays from one direction into many directions,(Fog, Diffusion)
  • Dispersion - Breaking up of light rays passing through different mediums. (Oil, etc.)
  • Filter Types

Conversion Filters -
Used to convert Tungsten Color Film to Daylight (85 filter,Orange) or to convert Daylight Color Film to Tungsten Light (80A or 80B, Blue)

Light Balancing Filters -
The 81 (yellowish) and 82 (bluish) series are used to raise or lower the Kelving temperature of the light in smaller increments to match the balance of the film.
Color Compensation Filters -
Used singly or in Combination to get any color correction to any degree desired.
Polarizing Filters -
Used to remove reflections from non-specular surfaces. Also makes colors more vibrant by removing surface glare.
Nuetral Density Filters -
Used to reduce exposure. They absorb all colors equally.

Combination Filters -
Two different types in single filter, such as a warming filter and a soft, or cooling filter and a nuetral density. Cuts down on number of optical surfaces in front of lens.
Filter Factors:
These numbers, which are supplied with the filter, are used to adjust exposure multiply the number by the exposure or ASA of the film.

For example, a filter factor of 1.5 would reguire 50% more exposure. So you would open the stop by half, or slow the shutter speed by half a stop. Easiest way to work is to change the ASA on your meter to a number 50% lower. So 400 film would behave as if it were 300 film. A factor of two would require a full stop adjustment. You would rerate your film from 400 to 200.

Mar 6, 2008

Shaping the Light with flags, silks and cukes-- Film Grip 101

Grip gear can be as important to crafting the lighting for a scene as the light fixtures. Often, more important--you can block, diffuse, shape, bounce and breakup the light using these tools. This is very crucial in creating a textured, realistic (or fantastic) look that is visually much more interesting than just blasting the light onto your subject.

Here's a look at the most essential grip items. These are all available to rent for very reasonable rates at film lighting rental companies. You can rent just a few items, or complete packages, even a grip truck to carry it all to the set. Or you may wish to buy. I’ve kept grip gear far longer than any camera gear. It never goes obsolete.

Century, or “C” stands are the most essential piece of grip gear:

Gobo Heads mount on top of the C-Stands:

These are used to hold extension arms:

Which in turn, hold everything else. The arms have fixed gobo heads with multiple holes for gripping flags, nets, silks, etc shown below :

Lighting Nets come as singles or doubles, like lighting instrument scrims, except the netting is thread, instead of wire. A red bordered net is a double, and cuts the light one stop. A green bordered net is a single, and cuts light by half a stop. Flags, nets, and silks come in these sizes: 18”x24”; 24”x36” ; 36×48 and 4’x4’.

Flags, (or cutters) are used to block or cut the light. You might use one to keep a light from shining into the camera lens, or to shadow a wall or another part of the scene.A silk is similar to a flag, but the black fabric is replaced with silk to diffuse rather than block light. Most of the time it is used to create a larger light source that throws softer edged shadows. But it can work as a flag, but one that makes a brighter shadow. It will cut more light than a net, and will also bounce more light into the scene.

Smaller versions of all three are called dots or fingers. These are used more for table top or product shots, but are also useful for many other purposes.

Long narrow flags are called cutters. These are usually 18″ to 24″ wide, and 4′ to 8′ long. When used as a “topper”, they block light from above, casting a horizontal shadow along the top of a set wall.

A cukoloris is a wood panel with random shapes cut into it. It’s used to break up light. Most of the time the light is focused through it so as to create soft, vaguely defined shadows, and not a hard edged pattern. Often these are made up quickly on the set by cutting random shapes into Foamcore boards.

Baby plates are special light stands that can be nailed to an apple box or a wall:

Reflectors are large 42” square boards mounted in a yoke, with a diffused silver side, and a shiny silver side.

They’re used outdoors to manipulate sunlight.

Butterfly overhead frames can hold large silks or nets for diffusing or reducing sunlight, or solid white or silver “Griffolyn” tarps for bouncing light, or large black "griffs" for blocking light.

They're strapped into 6’x6’, 8'x8' 12'×12’, and 20'×20’ frames and are held up by large “high roller” stands:

To keep all these stands from tipping over or blowing away, sandbags are placed on the legs.

Sandbags are usually available in 5, 15, 25 and 35 lb weights. When used with large reflectors or butterfly frames outdoors, several of the heaviest ones may be needed on each stand to keep everyone safe when it is windy.

Apple boxes have numerous uses from lifting props, to making actors taller, to seats for the crew. They come in full, half, quarter and pancake sizes.

Collapsible reflectors made of fabric are usually called Flexfill's or Photoflexes (brand names). Sizes range from small 24" diameter discs, unfolded, to 48" diameter, or even 48" x 96" rounded-off rectangles. The most common type are white on one side and silver on the other. But gold sided and other color variations are also available. They're light enough to hand hold, or can be clamped to a stand.

Grip Blankets (also called Sound-blankets) are multi-purpose, from deadening sound reflections to protecting location floors and furniture. Also called furniture pads, they’re usually considerably heavier than the ones found in moving stores.

This is just a very basic overview of the world of film grip equipment, to get you started. There's much more, and I'll be expanding on most of these in future posts.

Mar 1, 2008

Who's afraid of the big bad rental house?

HD / Video Camera
Rental Checklist

When I talk to people just getting into advanced video production, I’m always struck by how obsessed they are with having to buy their own gear. And of course they’re usually stunned at the cost of all of it. Though I think a five thousand dollar camera is cheap, relative to the cost of the gear used to produce feature films and commercials, it’s still expensive for an individual.

So I ask them — “How many movie cameras do you think Steven Spielberg or Peter Jackson own?”

The answer is, probably none–or at least none that they use to shoot their movies. They rent. While there are a very few directors who own their own gear, (Robert Rodriquez and George Lucas come to mind), these are by far both the historical and present exception. Producers generally rent all of it, whether they are shooting a commercial, a corporate video, or a feature film.

   For that matter, if you want to shoot with Panavision equipment, you have no choice, as their cameras and lenses are only rented, never sold.

The reasons are many. Prime among them is that they just don’t use such an expensive item often enough to make it worthwhile. It’s like buying a motor home that you’ll only take out once a year. Also, no one camera or lens is perfect for every task. And equipment is updated and obsoleted all the time. By renting, a producer can always have the most up to date equipment– and know that it’s in perfect operating order, completely checked out by the rental company before it’s picked up. Plus there’s all the ancillary lenses, specialty cameras, camera mounts, filters etc etc that need to be rented anyways. That gear can easily end up costing as much as the camera alone. So it makes sense to rent it all as one big package. When the production wraps, it can all be returned to the rental house– no concern about paying for a place to store it, or pay for maintenance on the inevitable wear and tear that occurs!

However–when renting a video camera, it’s vital to check it out before leaving the rental facility.
–The personnel there will be glad to see that you are concerned about their equipment.
–They’ll likely have a space set aside just for customers to check out gear.

Perform the following checks:

  • Batteries charged?
  • Camera powers on, from both batteries and AC adaptor?
  • Image in viewfinder? Image from monitor out of camera to a monitor?
  • If renting a monitor, is the monitor working? Set up monitor to color bars from camera to test.
  • Insert tape, make test recording. Play back test on color monitor.
  • Lens Check. Check for dirt and scratches, front AND back of lens.
    –If using filters ensure that filters fit on lens, no stripped threads.
    –Check all rented filters for scratches.
  • Back focus check. Use a backfocus chart to check backfocus of zoom from full telephoto to full wide.
  • Check condition of additional lenses you are renting. Make sure they fit on the cameras and are correct type, and cable connections fit.
  • Check that audio gear works in connection to camera. Do an audio playback test.
  • Tripod mounting plate in case, and correct one for camera, with mounting screws?

If unsure of any camera function, or operation, ASK QUESTIONS!

Do it now before you are on location.
Get a contact phone number for after hours problems.

Why I'm Here, and So Can You!

Hi, I’m Steven Bradford, and I’ve been a professional cameraman for over 25 years. I created this blog to share some of my experience with lighting and camera work, whether for film or digital video. I’ll be posting articles explaining both underlying theory for lighting, and useful tips and techniques for getting great pictures.

Anyone who has met me knows I love to share my experiences and knowledge, especially anything to do with my career choice as a cameraman. I’ve had some static web pages up for a long time, and I’ve taught workshops and college courses in film production. I also was the director of a film degree program at a four year college. Now I’m back to work as a full time free lance Director of Photography.

Over the years, I’ve come up with what I think are some clear and practical explanations of lighting and camera concepts. My goal is to use this blog to put those out there to a wide audience and with luck get some feedback and learn some new things too.

Here's my most current demo reel, with film and video examples from productions I've shot, in film and video.

All original material on this site created by me is copyrighted to me, Steven Bradford, and I reserve reproduction rights. Other websites and blogs are free to directly link to this site or to the pages on it. Images and text may only be posted or quoted on another web site if they link back to the original page where they appeared on my site, and show a credit to me, or to at the linking page.

If you are a teacher, and would like to use one of my pages in your classroom, you may display it directly from on a screen in your classroom with out seeking prior permission for me. This applies to K-12 and college uses, whether your school is a private, public, or proprietary institution.

Contact me directly at for any other uses, including printing out for distribution to a class.