Light Meters

[Jonas Scott]

Hello,

I would like to know what experience people have had regarding light meter use with the Canon Xl2 or 3ccd in general. Although the Canon XL2 does have one built-in, would it still be wise to invest in a light meter?

So in short, what do you as filmmakers do to control and meter light in your films?

And I do apologize if there was a similar thread before--I searched but was unable to find one.

[David Tamés]

If you're close to the monitor and/or camera, and your camera as a good spot meter function (like the Panasonic DVX, HVX, and Varicam) there is little need for a meter in most cases, the spot meter in the camera gives you an excellent exposure tool, as does a waveform montior (the old fashioned video way), however, where I've found a meter very handy (I like using a Minolta meter that gives me direct footcandle readings) is when you're doing lighting setups and you can't be depending on a monitor all of the time. I've done tests which map meter readings to IREs on the video, so I can roughly determine how many footcandles I need here and there on the set, so I can light without having to point the camera into the scene all of the time. Also, a digital camera with a historgram feature is also a useful exposure tool.

[Eb Samba]

Jonas
David is right. The simplest and cheapest way to go is to use your cameras Spot Meter. I use my XL2's spot metering and a digital camera. With my digital camera, I can measure the amount of light available when the flash is turn off.

[Chris Hurd]

Moved to Photon Management from Canon XL2.

[David Fleming]

There are basically two flavors of light meters. Incident and Reflected light meters. Viewfinder meters of any kind are reflected light meters; they tell you how much light the subject or scene is reflecting back to the meter or camera. An incident light meter tells you how much light (in lux or footcandles) is hitting the spot where you put the meter. Most incident light can be spotted by the whitish dome over the sensor.

Although photographic Incident light meters (sometimes called ambient light meters) are great they are expensive. They have the advantage of being calibrated in F stops at particular film and shutter speeds. Many of them can also capture flash light output which is not particularly useful for video.

A much cheaper and equally effective option is an inexpensive ambient (Incident ) light meter often sold by electronic test equipment distributors. I think I paid less than 50 bucks for mine and its reads the Incident light level in Lux. Electricians use these to verify light levels in different parts of buildings and such. You basically turn it on and read the display.

One you understand a few things about light the mystery of the photography meter calibrated in F stops goes away. First you should know how much light your camera needs for a good exposure. I think most ENG style camera are rated very specifically with light requirements, but I have read that most modern studios are light to about 1000 lux so I generally shoot for that.

When I want to set up an interview with 2:1 ratio (which is generally considered appropriate) I fire up the key and check the level. If usually position it to get around 1000 lux so I know am going to be ok. I then fire up my fill light and move it until my total goes up to 1500 lux meaning my fill is adding 500 lux to the scene and creating the 2:1 ration I am looking for.

I F stop relates to twice as much or half as much light so you can do some very simple math to figure out the 5000 lux is 1 stop less than 10000 lux and so on. I made a little label to stick on the back of my meter so I can quickly reference iris value to a particular light level with 0db camera gain.

Hope that helps