T436 - Fall 2007 - Week 3

Exposure & Image Control

Covers topics:

Continuity (Brown chapter 5)
Exposure (Brown chapter 6)
Filters (Brown p 230-240)

Next week chapters 8 & 9 (lighting)

Announcements/Reality Check

All Cinema Technique papers are due this Wednesday. We'll still present reports according to the schedule on-line.

Please keep up with the readings. We're working our way through most of the book this month. There will be a quiz on what we've covered so far in a few weeks.

Bring your gray cards and light meters to lab this week. (Also, I added a PDF of the Sekonic L-558 instruction manual to our website if you want to peruse it before Wednesday's lab.)

Please remember that I'd like to get at least one treatment or script from each of you by next Wednesday. Even if you don't consider yourself a writer, take a stab at it. This is worth 10 points. Especially needed are stories that are visually driven (not dependent on dialog). It's also good to find pieces we can produce here in the studio.

I've created a listserv for T436 talent. You'll get an email this week saying that you've been added to it. Please send me any interested actors/actresses you know of or meet, and I'll add them to the list.

I'll have fliers for the callout on September 23 this week.

Review from last week / chapter 4

Be sure you know the various types of camera moves and what they accomplish

• Punch-In
• Tracking
• Countermove
• Reveal

Also remember the various types of mounting devices:

Handheld

Types of Camera Heads:

• Fluid head
• Geared Head
• Remote Head (like on our jib)
• Friction Head (not used much)
• Underslung Head

High Hat - Low to gound mount

Dollies

Cranes

Motion Control (Good examples include Michel Gondry's Kylie Minogue video "Come into My World" (with some awesome difference keying and layerin g) or clips from Amelie)

Continuity (chapter 5)

Content (props, clothing, etc.)
Movement (rock in)
Position (props)
Time (not clocks- but how long it takes to do things and for time to pass)

The Prime Directive

Do not create confusion and distract the viewer from the story

The Line

Can be established with actors, gestures, objects and actions

Can move and must be continually re-addressed

According to Brown, Screen Direction "gives the audience clues about the story and helps keep the audience from getting confused about where someone is or what they're doing."

Cheating (see chapter 1)- This is moving objects and actors to more favorable positions in order to get the proper shot while maintaining visual continuity. For instance, say you need two angles of someone putting makeup on in front of a mirror in a bathroom. You can shoot an OTS shot of them showing the mirror for angle #1. For angle #2 we can position them away from the mirror and move the camera in, shooting them head on, looking directly above the camera as they apply makeup. The audience doesn't know the actor has been moved away from the mirror since we're shooting from it's point of view.

Occasional exceptions: when character positions are locked and established (in a car)

Cuttability

20 degree rule.  The image must change by at least 20% for it to be cut-able.

The 30 degree rule works fine with it.

6 types of cuts:

1. Content (Basic cut to add more info)
2. Action (aka a continuity or movement cut) Used when action starts in one shot and continues in the next. Opening a door for example. It’s ALWAYS better to cut on action.
3. POV (aka “look”) The character looks up. We then cut to what the are looking at.
4. Match – transitional device. The objects need to match up. (spinning fan on ceiling in Apocalypse Now to chopper blades)
5. Conceptual – 2001 Space Odyssey - bone to spaceship
6. Zero – When the cut should be invisible. (It never happened)

Exposure (Chapter 6)

f-stops

F-stops show a ratio of focal length and diameter

Remember that going up or down one whole stop either halves or doubles the amount of light coming into the lens.

In other words, changing by one whole f-stop changes by a factor of 2 (or 1/2).

whole f-stop	1	1.4	2	2.8	4	5.6	8	11	16	22	32
1/3 f-stops	1.1	1.6	2.2	3.2	4.5	6	9	13	18	25	36
	1.3	1.8	2.5	3.6	5	7	10	14	20	29	40

 

An f-stop of 1 is the largest opening one could theoretically have.

Focal length review:

Focal length = distance form optic center to target

f-stop = focal length / diameter of lens

Inverse square law

Point source lights’ intensity is inversely proportional to the square of the distance

Assume a light casts a quantity of 100 footcandles at 10 feet

• At 20 feet it will cast 25 footcandles (100/2x2)
• At 30 feet it will cast 11.11 footcandles (100/3x3)
• At 40 feet it will cast 6.25 footcandles (100/4x4)

Lighting

Incident vs. Reflected light

18% gray card – incident equals the reflected amount.

• ASA stands for American National Standards Institute or American Standards Association
• ISO stands for International Organization for Standardization or International Standards Organization

Also understanding basic limitations of the medium is important. The Zone System helps

Zone System

Understanding how to use is key to lighting scenes. While we can have more than 10 zones, this is a good number to use for video. For video, Zones 0 through 9 give us 10 zones, which can correspond to 5 f-stops, and easily transferred to 0-100 IRE levels on a waveform monitor.

Blackest black is Zone 0
The whitest white is Zone 9
Anything at Zone 10 is overexposed
The next lighter zone (Zone 1) corresponds to an f-stop of difference
Zone 5 is ?????

 

 

(18% reflectance) On a waveform monitor, this is about 55 IRE

Filters

Can be round, square or rectangular
Square are usually used with a matte box
Round filters can be attached to the lens

Color compensation
Color correction
NDs
Graduated
Attenuator
Diffusion
Polarizing
Special Effects

Always think in terms of f-stops and how you are affecting them.

Gain

Every 3 db of gain is 1/2 of a stop. 6 db of gain is a whole stop.

ND filters

Comes in	.3 or ND3	.6 or ND6	.9 or ND90	1.2 or ND12
Takes off (in stops)	1	2	3	4

Polarizing filters take of 1.5 to 2 stops

Problem Solving:

You are on the beach on an overcast day. You need to shoot some video of someone walking along the shore. You want to use a 100mm lens at f-2 in order to have the proper depth of field and angle of view. However your light meter tells you that you ought to be shooting at f-4. What should you do?

Solution: You need to figure out the difference between the actual reading and the desired f-stop. The difference between f-2 and f-4 is 2 f-stops. Therefore if you dropped in an ND filter of .6, it would take off two stops.

Misc. Filter info links:

• http://www.tiffen.com/products.html?tablename=filters&filter_format=Larger%20Format
• http://www.youtube.com/watch?v=ssx40e6Jrts
• http://photo.net/equipment/filters.html
• http://www.bhphotovideo.com/find/Product_Resources/filterIntro.jsp

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