to resume
Flash

Flash Unit
•portable
•safe
•simple to use
•attaches easily to camera
•fast duration makes it easier on subjects eyes

2 types of flash
•Combustible Flash
operates by igniting and burning a thin metallic element within an oxygen filled bulb

•Electronic Flash
operates by passing a pulse of electricity through a gas filled tube- causing an intense burst of illumination

William Henry Fox Talbot discoverer of this technology

Flash unit consist of:
1. Power supply (usually a battery or AC circuit) designed for rapid recovery and long life
2. Set of capacitors (stores electric energy)
3. Triggering Circuit (releases energy)
4. Gas Tube filled with an idle gas (Xenon) because its inactive it can be used 1,000’s of times
5. A Reflector

Color Temperature of light is 5500k (sunny noontime day)
Light output of flash is rated in terms of BCPS (beam candle power seconds)
Recycling Time-time it takes unit to recycle
x-sync fire a few milliseconds after the shutter is released so shutter will be fully open when the burst occurs


A flash unit is designed to provide a measure of intense light timed to the shutter speed
(synchronization or sync )

Focal Plane shutters will only sync at settings between 60th and 250th

•you can use a slower shutter speed, but you will get out of sync photos with a faster speed if using a faster speed than what your camera states (page 328)

Leaf shutters will sync at any shutter speed
•flash will produce its brief burst as shutter is wide open regardless of shutter speed






Exposure=Time X Instensity

Unless special flash metering equipment is used, the intensity of the flash cannot be mea sured and the amount of light that will be reflected from the subject must be estimated



5 variables that will affect the exposure settings:
1.
Flash output-various electronic flash units produce different intensities of light
2.
Film speed
3.
Flash to subject distance-main variable factor determining exposure Inverse Square Law
4.
Environmental Reflectance-
•room with white glossy walls will reflect more light than room with dark colored walls
•shiney objects reflect more light than dark dull objects
•as camera is moved from one angle to the next surface textures and coloration of the space will affect exposure profoundly
5.
Type of Reflector




3 Major types of flash


Manual Flash
•photographer determines the exposure and sets the camera’s aperture and speed by hand

Automatic Flash
•Photographer presets the film speed and an aperture (f-stop), the unit then determines the exposure manually

Dedicated Flash
•the automatic flash unit and camera are designed into an integrated system, the film speed is preset and the system sets the proper flash exposure


3 Basic Methods of Metering with a Flash

Automatic Calculation Flash Metering Manual Calculation



Automatic Calculation
•cameras conventional light meter
is not used to determine the camera settings for flash photographs

1. Set the cameras speed to the proper sync
2. Set the flash to the correct ASA/ISO
3. Reading from the calculator, set the camera’s aperture to that recommended for the desired operating range
The flash will then control the exposure by controlling light output
A built in sensor will measure the light reflected from the object

Sufficient Light Indicator

Signals if the flash was adequate can check before a picture is taken by pressing the test button

Manual Calculation
•most units have a calculator to which
1. desired flash output
2. the ASA/ISO speed
3. Flash to Subject Distance

OR you can use guide numbers usually given in the flash manual and/or sometimes packaged with films

Guide Number divided by distance = F stop

Used as an aid-may need to be adjusted if film is continually being overexposed-use higher ASA
or underexposed-use lower ASA


Flash Metering
Using a Flash Meter
(Demo on This)













Lighting Techniques for On Camera Flash


General Principles learned last lecture
•single dominate light source
•filling in the shadows of this light source
•accents to rim of subject help reveal it’s shape and contour to separate it from the back- ground

To achieve these with a flash might be a little difficult because you can’t see the light thats going to hit it
HENCE-Thats why we have been doing light studies!!
By doing these studies, you should be at the point now where you have the general idea what angle the light has to be to create the shadows you want.


Most Flash photography is carried out with a single flash unit.

Flash on Camera

•easy, convenient
•produces flat lighting
•produces a bounce back glare from walls and shiney objects
•produces unsightly shadows on background if subject is too close to it
•red eye

Bounce Flash
Bouncing light from flash off of a surface onto the subject (ceilings, walls, bounce reflectors)
•flashes with swivel heads
•or unit can be removed and aimed upward
•produces a soft key effect (diffused)
•also can bounce off fill card


Automatic or dedicated Flash
•will work as long as sensor is directed toward camera

Manual Flash
•instead of calculating camera flash to subject distance, calculate flash to reflected surface to subject
then the indicated exposure should be opened up one or two stops to compensate for additional absorption and diffusion
•Further increases should be made for dark or highly textured walls and ceilings or larger rooms
•BRACKET!!
•more accurate to use your light meter


Flash Off Camera

This will enable you to use lighting above and to the side of the subject, producing the most natural set of highlights and shadows

This can be achieved quite simply by attaching flash to camera by means of a sync cord and hand holding it above the camera and to the side

Move further away by attaching to light stand or using a special clamp

Off camera flash produces a dominate set of highlights and shadows but by itself cannot produce the additional fill light to fill in the shadows
•use of fill cards or placing subject close to wall
•small bounce card attached to the flash
-used to open up shadows
-add catchlights to eyes
-in no card is available 3 or 4 fingers cupped by flash


Flash Diffusion
–throw a white handkerchief over hood
***be sure sensor is not blocked***
•for auto cameras-compensate for light loss by selecting a longer range setting
•for manual calculate normal and then increase 1 or 2 f stops


Open Flash (painting with light)
used in very dim ambient light situations with stationary subject
1. darkroom, if possible
2. open shutter and allow it to remain open
3. carry off camera flash unit to several positions, fire in each location
-one in key light position
-again from a fill light position
-from behind to create a “rim”
4. after firing flash several times go back and close shutter

***Can also use this technique if you don’t have a sync. cord


Fill In Flash
A flash can provide a main light source or can be used as a fill in
photos taken in bright sunlight have high contrast with deep shadows

You need to fill in the shadows using fill cards or reflectors or a
fill in flash
-the trick is to provide an illumination just strong enough to fill and not overpower the rest of the natural light
a. placing flash at proper distance
b. reducing brightness of flash to a 2 to 1 desirable



Flash and Slash

A variation of a slow shutter speed and a fill in flash will produce
•blurred motion with sharp images

1. Set flash to overpower normal exposure by 1 or more stops
2. Slow Shutter Speed

Flash for Action

Remember it is the burst of light not the shutter speed that generally determines the exposure

Under bright lighting conditions make sure shutter setting is not too slow
•show shutter speed will cause a blurry 2nd image
•turn out some of lights in room
•slower film speed
•higher intensity flash

Because of rapid fall off of light over a distance, foreground subject will be brighter than background, the further away the background the darker it will appear

Flash Problems

Because you can’t see the burst of light it’s hard to predict this your flash will effect the subject
The only way to predict this is experience

Red Eye
caused when flash is placed too close to camera lens axis
•move unit further away from camera
•extender with hand
•photograph subjects looking slightly away from camera

Uneven Coverage
occurs when the lens angle of view is wider than the flash units angle of illumination
•use wide angle adjustment on flash
•white handkerchief over flash unit to diffuse and spread light
•bounce flash technique

Uneven Illumination
near objects brighter than far objects (inverse square law)
•select camera angle that places subjects at equal distance
•use bounce flash
•multiple flash units




Flash Reflection
bright hot spots off of reflective surfaces
•facing blank walls or flat surfaces at an angle of about 45º rather than head on
•avoid mirrors
•eyeglasses-tip downward have subject turn slightly off camera

Distracting Shadows
subject being placed too close to background
•move subject away from background
•raise flash higher so shadows hit lower

Empty Shadows
occur when flash unit is placed a too extreme of an angle to the subject without light
•use fill cards
•multiple flash units

Partial Exposure
only part of image is exposed
•out of sync shutter speed


Contacts and Cords

Hot Shoe-built in mounting bracket to which the flash connects

PC Socket-connecting camera to flash unit by means of a sync cord

Special Features and Accessories

Thryster Circuit-preserve the energy in the capacitors following the flash discharge and preserves it during recycling time

Angle Adjustments-a few units feature a zoom head-produce wide, normal, or narrow angle of illumination

Swivel Heads-unit may be attached to camera but directed away from subject

Camera mounted sensors

Handle Mounts

Detachable Reflectors
if detached light will move in all directions
the direct rays will serve as key light and the runaway rays will act as a fill light

Manual Override

Bounce Card Attachments-acts as a substitute ceilings

Extension Cords-enable the flash to be moved around

Wireless radio slaves-
Flash Slaves-responds to light by photoceptive cell that connects to flash units sync cord

Light Stands-small enough to fit in gadget bag, yet extendable to great heights, and strong enough to hold a flash and umbrella

Reflectors
•umbrellas broader, more flattering light (diffused)
•snoots-for a more direct light

Gels-for color photography

External Power Packs
•battery packs
•typically worn on photographers belt and attached to flash with cord
•can provide up to 2,000 flashes
•great for weddings or “events”
•quicker recycle time, about 1 to 4 seconds