Time And Exposure

Tony SchountzFCDCC

December 2011

Shutter Speed

• Shutter speed controls the duration of light striking the sensor

• Most DSLRs have shutter speeds of 1/4,000” to 30”

• As a rule, handheld photography can be done using a shutter speed that is the reciprocal of the focal length of the lens

• If you’re shooting a 200mm lens, then 1/200” of a second is the slowest shutter speed you should use without a tripod

• Image stabilization (IS, VR, OS, etc.) can reduce this up to 4 stops, or 1/12” with a 200mm lens.

• Faster shutter speeds are used to stop action

• Slower shutter speeds are used to emphasize motion

Stopping Action

• Fast-moving objects

• Cars

• Planes

• Baseballs

• Bicycles

• Sometimes flash is required

• Very fast objects

• Slow maximum shutter speed

• Specialized releases

Dali AtomicusPhilippe Halsman

Slow Shutter Speed

• “Time Exposure”

• Longer shutter speeds

•Tripod or other stabilizing device

• From 1/30” to about 1/4” mirror lock-up (MLU) is often required

• “B” (bulb) setting allows prolonged exposures

•Not all cameras have a “B” setting

•Requires electronic release

•When battery is exhausted the shutter will close

•Reduce ISO to lowest setting

Equipment For Slow Shutter Speed Photography

•Stable tripod

•Remote

•Wired

•Wireless

•Neutral density filters

•Pan head

Neutral Density Filters

•Reduce the amount of light passing through the lens

•They are called “neutral” because they do not cause color shifts

•Allow longer exposures in bright conditions

ND 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0

Stops

1 2 3 4 5 6 7 8 9 10

Neutral density nomenclature

Lee Big Stopper

•ND3

•10 stop reduction of light transmission

•A 1” exposure becomes a 17 minute exposure

•$160

1/30”

2”

30”ND1.2 (4 stops)

Panning

• Following a moving object

•Object remains (relatively) sharp

• Background exhibits lateral motion blur

• Pan heads are great for this, but handheld can work, too

Moving with the Object

Deleting Objects

During a long exposure, moving objects are not recorded as well as static objects, thus they disappear from the image

Night Photography

•Often requires long exposures or higher ISO settings

•Noise becomes more of an issue

•Some cameras will take a second exposure without recording light

•The noise from this second exposure is subtracted from the first exposure

Lightning

• Specialized equipment to trigger the camera

• At night, just leave the shutter open for several seconds

• Set exposure based upon lighted object

• Wait for the lightning to strike

• Lighting is so bright that it will typically show up on the image, even at small apertures

Interval Timer

• Releases shutter at user-defined intervals

• The number of releases are also user-defined

• Also acts as a single-shot release

• Perfect for time-lapse photography

• Recorded images can be assembled into a “video” using widely-available software (iMovie on Macs)

Interval Timer

Time-Lapse Photography

• Set camera to JPEG

• 1900x1080 is considered “high-def” for display on televisions

• This will maximize the number of shots written to your camera’s flash card

• Determine exposure and set it

• Be careful with autoexposure if you expect dramatic changes in light, such as sunsets or sunrises

• Set the interval timer’s:

• Intervals (e.g. one shot per 10 seconds)

• Number of shots (up to 999)

Assembling the Movie

• Import still images into software

• Set frame-rate

• Varies depending on number of frames, but 12 frames per second to 24 frames per second is often used

• A 1 minute video at 15 fps contains 900 images

• Add audio, if desired

• Export as a movie file

Videos

•http://vimeo.com/18554749

•http://vimeo.com/15368982