Unit 4: Flash Photography

Tim Clouse

What Do I Have to do for Week 4• Read Chapter 5 of your text Crime Scene Photography

and Chapter 9, pages 457-459 concerning Nighttime Accident Photography.

• Review key terms • Complete the discussion questions regarding the basics

of camera operation with various lenses. • Participate in Web Field Trip • Complete and submit Project 1 • Complete Essay • Attend the weekly seminar • Respond to the discussion board

What is a flash?

• 1830 the first flash bulb was created • It has pro’s and con’s • Used to create artificial lighting for

photography purposes • Lights the primary subject • Fills light in shadow areas

Types of Flashes

• In-Camera Flash Unit •Hot-shoe Flash Unit •Slave Flash Unit

Guide Numbers

• A means to discuss a flash unit’s relative output power

• Measured in feet or meters• Vary by ISO (Most are compared at

100 ISO)• Shutter Speed

Guide Numbers

• GN 160= Very Strong and expensive flash

• GN 120= Norm with many LE agencies • GN 80=Less powerful but may be used by

LE• GN 56=Weak Flash • GN 36= In-Camera flash

Guide Numbers

• GN/distance=f/stop• So if we have a GN of 120 and a distance of

12’

• 120/12=10, so 10 would be the recommended f/stop or f/11

Flash Sync Speed

1=1 sec. 60=1/60th of a sec. 2=1/2 sec. 125=1/125th of a sec.4=1/4 of a sec. 250=1/250th of a sec. 8=1/8th of a sec. 500=1/500th of a sec. 15=1/15th of a sec. 1000=1/1000th of a sec. 30= 1/30th of a sec. 2000=1/2000th of a sec.

4000=1/4000th of a sec. B=As long as the button is push shutter is open

Sync Speed

• Synchronization Speed • Is the fastest shutter speed at which the

camera should be set whenever an electronic flash is to be used.

• Camera’s vary in sync speed • You should get familiarized with your camera

before using it

Indication on Shutter Speed Dial

• Sync speed will be indicated on the dial as • RED

• X or X• Or some other indication

What does it mean to Sync

• At this speed • Shutter is completely open • Flash goes off • Shutter then closes after flash has gone off• The camera documents the scene which is

now filled with light

Faster shutter speeds

• The camera has a SYNC speed for a reason• Higher speeds may not capture the light• High shutter speeds may only capture half the

frame • Lower speeds could blur the image • “Ghost” images could also result in slower

speeds

Flash and ISO

• Newer flash units have an ISO setting just like the camera

• Automatic flash units need to know the correct ISO to ensure good shot

• DX coding

Manual Flash Mode

• Flash uses all power available to it• Adjustment of the shot is with the f/stop• The use of GN now have to be used• Newer flash units show this information • Older flash units have a dial which indicate the

f/stop

The rule of the “Normal” Room

• 10’ x 12’ room• White ceiling 8’ to 9’ high • Light colored walls • Why is this important to know? • Light not only travels straight, but upward and

laterally

When not to trust the flash recommendation

1. In smaller rooms 2. In larger rooms 3. Outside

Bracket, Bracket, Bracket, Bracket

The Flash Head

• On-Camera vs. Off-Camera• Flash unit will flash the light higher than the

lens at close distances • With closer distances mover the flash lower to

get more light on the subject• This can be accomplished by using a PC Cord

or Remote Flash Cord • P.226

Red-Eye Effect

• Flash is in hot shoe or directly over camera • Light from the flash enters the eye • Reflects off the blood vessels at the back of

the inside of the eyes • Travels directly back toward the camera

To Keep Red-Eye out of the Shot

• The use of a camera bracket, keeping the flash off of the camera

• Separating the flash from the axis of the lens• The closer the flash is to the lens the more

likely Red-Eye will be produced • Brackets also help in holding the camera p. 228

Flash-Camera Orientation

• The film plane and flash are in the same shape • For this reason the flash should always be in

the same direction as the film plane • If not there could be a shadow effect on the

photo• Camera vertical=Flash being vertical • Camera horizontal=Flash being horizontal

Problems with Manual Flash Mode

• Slow • Battery drain • Recharge time • Bracketing

Inverse Square Law

• As light spreads outward from a point light source, its intensity varies inversely by the square of the distance traveled.

• Light travels in a cone like area• As it travels it becomes weaker • I=1/D^2• I=Intensity of Light • D=Distance

Effect of Inverse Square Law

Flash HeadBrighter Light

Less Light on subject due to light spreading out and dissipating

Subject

Think of it like a flashlight or head light on a car, as the light goes out it spreads over a larger area and then becomes dimmer the farther it goes out

Less light on the subject means it gets darker and needs more light

For our purpose

• No photos less than 2 feet from the camera

• No photos beyond 30 feet from the camera (DOF)

Built in Flash Units

• Has a low GN • Only use if it is all you have• Red-Eye will probably happen

Fill in Flash • Use when part of the scene is strongly lit by

ambient light and the primary subject is in a shadow area.

• Idea ISO is 100• Take a meter reading filling the frame in the

bright light with the CORRECT shutter speed • Flash should be in Manual Mode for proper effect • Get the proper distance as listed on the flash • Adjust flash • Take photo • PRACTICE, PRACTICE, PRACTICE

Oblique Lighting

• Shows more detail in a 3D effect • Shows more depth and the texture of the

subject

• Shoe prints • Tire tracks • Finger print latent's• Bit marks

Bounce Flash

• Mirrors • Smaller rooms • Glass • Liquids • Flash must be set to manual mode p. 280-283

Painting with Light Over Large Scenes

• Photographing a large scene at night with one flash over multiple times with one camera

• More than a one person show • Communication is the key • Again, PRACTICE, PRACTICE, PRACTICE!!• Then PRACTICE some more

Timed Exposure

• Also used on larger scenes • The use of the B button for timed exposure • f/stop set at 8 • Both Painting with light and Timed Exposure

methods are good for Crash Scenes

Project 1• Photograph #1: You are to set up some type of item that could be used as

a weapon in a crime, i.e., gun, knife, screwdriver, etc. Position the weapon in such a way that it is in the shadow caused by sunlight similar to those examples on pages 264 & 266 of your text. Attempt to use a flash-fill technique to illuminate the weapon. Depending on the type of camera and accessories you have to use will affect the results of your photograph. Do not worry about trying to make the photograph turn out perfect. The idea is to learn from the technique.

• Photograph #2: Set up another similar piece of evidence, but place it in an area of total or almost total darkness. This photograph can be taken indoors or outdoors. It can be any type of object, but you can use the same from the first photograph if you wish. Take a photograph using direct flash technique, not bounced or diffused. You should be close enough to the object to be able to identify what it is in the photograph.

• Write an essay describing the results of your photographs. Include exactly what type of camera you used (brand name and model, digital or film), your ISO settings, type of lens (either the exact focal length such as 50mm or fixed pre-focused). Everything about the camera should be described in the essay. Did your photographs turn out the way you expected? Why or why not? Describe in detail why your photographs turned out the way they did and what could be done to improve the photographs if anything. What other equipment would you have used if you had access to it?

• If you took digital pictures or had film converted to digital, submit them with your essay. Be sure to name your photograph files with your last name and photo 1 or 2. Example: smithphoto1.jpg & smithphoto2.jpg. All digital photographs submitted should be in jpeg format. If you used film and are unable to scan them or have them processed as digital you do not have to submit them.

Next week: Week 5

• There will be NO seminar next week • If you have work that you are behind on get

caught up this week and get that work turned in for grading

• Week 6—begin reading Chapter 6 See you in two weeks