Q G WGBH Public Television Quality Workshop 1 The Great Frame Rate Debate Bruce Jacobs - Moderator Mark Schubin Larry Thorpe Doug Trumbull.

QG WGBH Public Television Quality Workshop 1

The Great Frame Rate DebateThe Great Frame Rate DebateBruce Jacobs - ModeratorBruce Jacobs - Moderator

Mark SchubinMark SchubinLarry ThorpeLarry Thorpe

Doug TrumbullDoug Trumbull

QG WGBH Public Television Quality Workshop 2

Film TraditionFilm Tradition Camera exposed 24 frames each secondCamera exposed 24 frames each second

Fast enough for illusion of motionFast enough for illusion of motion

Shutter normally open ½ the time = 1/48 secondShutter normally open ½ the time = 1/48 second Longer shutter = more blur, less judderLonger shutter = more blur, less judder Shorter shutter = less blur, more judderShorter shutter = less blur, more judder

Projector shutter closes twice for each frame = 48 fpsProjector shutter closes twice for each frame = 48 fps Avoids flicker (if projection is dim)Avoids flicker (if projection is dim)

QG WGBH Public Television Quality Workshop 3

US Broadcasting US Broadcasting TraditionTradition Camera exposed 60 fields each secondCamera exposed 60 fields each second

(An Interlace “field” is an inferior ½ “frame”)(An Interlace “field” is an inferior ½ “frame”) Couldn’t “store” image and display twice, like film doesCouldn’t “store” image and display twice, like film does Originally the rate was the power line frequencyOriginally the rate was the power line frequency Avoided flicker on early CRTsAvoided flicker on early CRTs Noticeable flicker on later large/bright/sharp CRTsNoticeable flicker on later large/bright/sharp CRTs

No shutter neededNo shutter needed 1/60 second exposure1/60 second exposure

QG WGBH Public Television Quality Workshop 4

US Broadcast Film TraditionUS Broadcast Film Tradition Film frames are shown 3 times, 2 times, 3 times…Film frames are shown 3 times, 2 times, 3 times…

It’s called “3/2 pull-down”It’s called “3/2 pull-down” Two film frames come out even with five video “fields”Two film frames come out even with five video “fields”

QG WGBH Public Television Quality Workshop 5

The New WorldThe New World Digital cameras can do anythingDigital cameras can do anything

24, 30, 60 frames per second, and more24, 30, 60 frames per second, and more Widely varying shutter speeds availableWidely varying shutter speeds available

Our broadcast distribution is constrained to 60Our broadcast distribution is constrained to 60 Internet distribution can be anything?Internet distribution can be anything? New TVs interpolate frames!New TVs interpolate frames!

QG WGBH Public Television Quality Workshop 6

Production DecisionsProduction Decisions Why 24 fps?Why 24 fps? Why not?Why not? What do I need to know to make it work?What do I need to know to make it work? Why not 30 fps, and avoid pull-down?Why not 30 fps, and avoid pull-down? Should I consider other frame rates?Should I consider other frame rates? What about 3D?What about 3D? When should I use unusual shutter speeds?When should I use unusual shutter speeds?

QG WGBH Public Television Quality Workshop 7

The “Film Look”The “Film Look”Issues Related to Shooting atIssues Related to Shooting atLower Picture Capture RatesLower Picture Capture Rates

Larry ThorpeLarry Thorpe

HD Image Acquisition Sought-for Creative “Look” encompasses:

LightingFocal LengthND FilteringDepth of FieldApertureFrame RateShutterResolutionDSP Processing

24 Hz Image Capture is a Historical Aberration…..But, 24-frame motion picture film was born exclusively in the context

of movie sound

This frame rate was perpetuated by the escalating constraint of motion picture film cost escalations with increased frame rate Failure of SMPTE 1988 agenda for 30-Frame film standard

Over many decades cinematographers honed the art and science of motion picture capture within the constraints of this severe temporal sub-sampling A much-loved “Look” emerged and is globally entrenched

Motion Judder is More Visible

The faster the image motion

The sharper the image in motion

The brighter the Scene content

The brighter the viewing screen

Cinematographer “Handles” to Manage Judder

A/D

Sample&

HoldAmplifier

CCDCMOSImager

BeamSplitter

OpticalLow-PassPre-Filter

PostFilter

A/D

A/DIR

NDFilter

LensLens

ImagerDrive Circuits

ApertureAperture ND FilterND Filter ShutterShutter Frame RateFrame Rate

Motion of the Camera (Pan, Tilt, and Dolly)

IMAGE FORMAT SIZE IMAGE FORMAT SIZE

Art of the DoP: Meticulous Control of Camera Movements

Art of the DoP: Shoot with Short Depth of Field