Meters

There are basically two types of light meters: Incident and Reflected. Since a Spot Meter has a very narrow angle of view which is employed very specifically, it might be considered another type of meter, but it still is a reflected light meter and so I will categorise it thusly. Finally, a whole other matter concerns colour; Colour Meters will be discussed here as well.

	Incident meters measure the amount of ambient light around the globe or disc that covers the photo cell (the thing in the meter that is sensitive to light). It is placed in the area where you want to get a general light reading and is pointed at the camera lens. With the half-globe attachment, this gives you an over-all measurement. Also, you can face it toward your key light for a reading of its output, then turn it toward your shadow area to get a reading there, then you would decide to either average the two, or decide which area to favour when setting your T stop. Most analogue incident meters, such as the popular Sekonic, give a reading of light output measured in footcandles, which then can be converted to T stops via setting your film speed (ISO, ASA, EI), matching up the marked arrow to the needle pointing at the footcandle number, and comparing the mark for your shutter speed (1/50 of a second for 24 fps) to the T stop marked below it. It sounds complicated, but it really isn't once you've got the meter in your hands. Digital meters usually skip the footcandle numbers all together. After you set your film speed (ISO) and shutter speed, (many digital meters give you the option of regular still photo shutter speeds as well as "cine" which are expressed as frames-per-second -12, 18, 24, 32, etc.- if you scroll past all the still speeds to find them) clicking the button will give you a reading directly in T (or f) stops, usually indicating in-between stops with a percentage.	Photos of examples coming soon!
	Reflected light meters measure the amount of light reflecting off a surface. The photo cell area (usually flat) is pointed AT the subject, not the lens, to get a reading. Most analogue and digital meters have a separate attachment that covers the photo cell, in place of the white half-globe or white disc, for achieving reflected light readings. It is important to note that a reflected light value is based on 18% grey (which is photographically the middle of the grey scale), so the reading you will get is the correct exposure for mid-grey. If you are metering a white wall, for example, you must remember to open up about 2 1/2 stops for it to appear white (and vice versa for a black wall). Un-tanned Caucasian skin is, on average, about 1 stop brighter than 18% grey... So if your reflected light reading off of your Irish actor's cheek says T4, setting your lens at T4 will make your actor, and probably your whole scene, look pretty dark. Using incident readings, and other readings around the room for comparison, you might set your stop to around T2 +1/2 or T2.8. Remember, this is where creativity comes in, after all, you are painting with light. Also, know the latitude of your film stock (how many stops brighter or darker than middle grey the film will allow you to see detail before your subject goes fully white or black). It is also a good habit to shoot a few seconds of an 18% Grey Card (get this at any photography shop), placed in the light where your main subject will be, at the head of every scene. This will give the lab people an idea of what "normal" is supposed to look like for that scene.
	A spot meter works just like any reflected light meter, except its angle of view is about 1 degree, which is a really tiny spot (marked as a circle in the window through which you view your subject). This handy toy allows you to measure the light value of a very small part of your subject, or a subject very far in the distance. You can use it from your camera position to measure the highlight on someone's forehead, the shadow under his chin, whatever, without having to get in your actor's face and annoy him. Remember, though, the T stop it gives you is for mid grey, so compensate accordingly. I like to take a few incident readings first (one in the highlight, one in the shadow, and one pointed at the lens), then use the spot meter for specifics. It is important to note that metering is not a technical task that you do just before you are about to roll camera. It is a tool to help you set and manipulate your lighting so you can achieve your desired look. Setting up all your lighting to your eye, then getting a general reading after, leaves too much room for error (like blown-out highlights or areas of unwanted blackness). Have an idea what T stop you would like to shoot at before you start lighting, then set your lights to your desired outputs, (1 stop over for this, 2 stops under for that, 1/2 stop over for the face, whatever) metering as you light. If light is your paint, then your meter is your brush.
	Colour meters provide information about the hue of a light in Degrees Kelvin. I assume you already know that colour films are balanced for either Tungsten (3200 degrees K) or Daylight (5500 K). Daylight, of course, varies in colour, from very blue when it's cloudy, to more orange when it's sunny. 5500 K is a pretty good average. You would use a colour meter when dealing with mixed light sources, to get an idea of what type of gel or filtration is necessary to convert a light source to the desired colour, if you want a specific shade, or an even colour across the scene. These meters give you information for compensating in the blue or orange range (as for changing a 2900 K household bulb to a 3200 K halogen-colour or to 5500 K to match window light), as well as for green/magenta (for fluorescent lighting) and other hues. I seldom have any need for colour meters, but if you have a chance to play with one and get to know how it works, you'll be all the better for it, I'm sure. Happy metering!

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