Photography Using Flash by pengtt


									       Basic Photography Using

4/24/2011    On Camera Flash   1
    Basic Photography Concepts
•   Automatic vs. Creative Modes
•   EV Equivalent Value
•   Lighting considerations
•   Histogram
•   Add Flash to you shot
•   Guides as starting points

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            Automatic vs. Manual
• Automatic is easy

    • Quality is good
    • I’m in a hurry

• Manual is difficult

    • To many things do I need to think about.
    • What are the advantages?

• The difference is consistency and control.

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   Automatic vs. Creative Modes
• To what extend do you want to have
• Creative modes
    – AV , TV, P
    – Manual
• Custom Features
    – First curtain vs. second curtain
    – High speed sync
• Histogram
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              Histogram in Camera

            To dark                     To bright

•To the left the picture is to dark, to the right it’s
too bright
•Balanced is in the center
•A valuable tool in camera
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              Exposure Value
• Three choices, all with limitations
    – Aperture 22, 16, 11, 8, 5.6, 4, 2.8, 2, 1.4,1.2

    – Shutter Speed100, 200,400,800.…8000

    – ISO- 100, 200, 400, 800,1600…. 24,000

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      Lighting Considerations
• What is your main light source?
    • Direction of the light
    • Color Temperature
• What affect do you want?
• Digital camera metering to 18% gray

    • Increase exposure for white
    • Decrease exposure for black

• Do I want, or need flash?

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            Using On-camera Flash
• Built in flash unit
• Add on flash units
    –   A or B type units
    –   EX vs. EV units
    –   Metering with TTL
    –   Consider using EV changes on flash unit
• Camera Sync Speed
• Considering a purchase?
• Off camera flash – subject for another time
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                             Light Fall-Off
                                  (Inverse Square Law)

                       5ft                                             5ft
    Light                              Illuminated area = 1                         Illuminated area =
    Source                             sq ft                                        4 sq ft

For a given light source intensity:
    -   Twice the distance results in 1/4th illumination (i.e., 2 stops lower)
    -   Three times distance results in 1/9th illumination (i.e., >3 stops lower)
    -   Four times distance results in 1/16th illumination (i.e., 4 stops lower)

    -   Decrease distance between closest & furthest subjects
    -   Back away from closest subject as much as possible
    -   Use Large Diffuser (limited effectiveness when on-camera)
    -   Use Bounce Flash (back wall, side wall, ceiling, reflector)

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       Flash Unit Guide Number
Guide Number shows the power of the flash unit.
Useful tool to estimate exposure when distance is
    Guide Number / distance in feet= Aperture
                                  580 EXII    7D
                            (mm)          14      15
                       Guide No           49      39
            f/                           (ft)    (ft)
                 2.8                      18      14
                   4                      12      10
                 5.6                       9       7
                   8                       6       5
                 11                        4       4
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   Add Flash to Composition
• As your primary light
    –   Soft vs. hard light (demo flash)
    –   Direct vs. indirect light (demo)
    –   Light fall off (demo)
    –   Ambient light (Demo)
    –   Color Temperature (demo)
• Used a supplemental fill light
    – Control shadows, Highlight subject, Create soft light, Contrast

• Light fall off
    – Flash on subject is not affected EV, background is (Demo)
    – Adjust EV as subjects appear further away (Demo bounce flash)
    – Guide Number / distance in feet = Aperture

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            Direct vs. Indirect light

•Direct light removes shadows and creates a flat
•Direct light is a hard light
•Bounced flash softens light and skin tones
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            Soft vs. Hard Light

•Look at the skin tones between a soft and hard
•Notice reflection of light from flash

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               Light Fall Off

•Example shows how illumination is less the
further apart the subjects are from the source.

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        Solution for Light Fall Off

•Consider bouncing flash to balance illumination
on subjects at different distances.

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                 Ambient Light

•In addition to your main light, you need to
consider ambient light.
    –Tungsten add an orange color
    –Fluorescent – blue of green tint added
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            Watch out for glasses!

•Direct light reflects off glasses.
•Also, “Red Eye” comes from reflection off of
the eye retina.
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     Color Temperature Solution

•Convert your flash to correct ambient light

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                 Light Fall Off

•Using Flash the light remains constant
    –Flash on subject is not affected by change in EV
    –Background illumination can be controlled with EV

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            Notice the back ground!

•By just changing the shutter speed you control
the color and texture of the back ground.

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            Want more Shadow?

•Add flash and to the extreme.
•Adjust the angle and distance of the flash to
control shadows.
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             Live Demo
• Grey scale demo showing manual vs auto
  exposure modes.
• Color demo showing manual vs auto color
• Additional examples

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           Starting Points
    Considerations/Rules of Thumb
• Read your equipment manual!
• Daylight- Rule 16: A 16, SS 100, ISO 100
• Flash on subject in Sun light
    – Sun behind camera -3EV to -1EV
    – Sun at 90 degrees -2EV to 0EV
    – Sun behind subject -1EV to +1EV
• Indoor consider your color temperature
• Consider bounce flash to direct or soften light
• Consider shutter speed & ISO to supplement background
• Shoot Raw to have 16 bits of data per pixel to work with for flexibility
• Look at the camera’s RGB histogram
• Shoot a manual practice shot, then adjust the settings to your
• Play with flash - practice

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