Understanding Shutter Speed in Photography, Study Guides, Projects, Research of Photography

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Instructor

Scott Campbell

07 - 22 - 15 PowerPoint is available on-line

 ecampus.matc.edu/policetraining

 Required Equipment: Students need to bring

their digital camera (digital SLR preferred),

lens, batteries, digital media, off camera flash

with remote cord, tripod (if available),

flashlight and note taking materials.

 Instruction manuals for their specific camera

and flash are suggested if available.

Introductions  Name /Title/Years of Service  Department / Dept Size  Experience with Photography  What are your Responsibilities with Evidence and Crime Scene photography  What do you want out of this class Guidelines & Best Practices

 For current Guidelines and Best Practices utilize

the website for The International Association for

Identification ( theiai.org )

 SWGIT Guidelines (Scientific Working Group on

Imaging Technology)

 Some of the information available

 Equipment

 Image capture, processing, archiving &

authentication

 Photography of latent, tire and footwear

impressions

 Crime scene photography tells a story to those who were not present at the scene.  Provides visual preservation of the scene, location and condition of evidence, and creates a permanent record  Aids in the reconstruction of events  Refreshes the memory of investigators and witnesses Introduction  Ensures accurate representation of the evidence for a thorough investigation and successful prosecution of the case.  Documents the location and condition of evidence  Photographs can help make or break a case. Introduction

Introduction  Remember, prosecutors, judges, juror’s, witnesses and victim’s families may view the photographs you take. Your work is not only a reflection upon your department, but a reflection upon you.  Photos should always be fair and accurate so they can be used in court Why do you need to spend so much time learning photography?  Not every scene will require you to:  Dust for prints  Collect blood or DNA  Cast shoe or tire impressions  Collect other trace evidence

However, all scenes require quality photographs

before any processing occurs!!!!!

Can’t I just use the camera’s

automatic setting?

 Quality modern camera equipment will produce very good photos most of the time. However, you can take better photos yourself if you understand basic principles and make manual adjustments.  The camera doesn’t know what your goal is and can produce a photo that is too light, too dark or out of focus.

Camera was on automatic – image too dark

Camera on “automatic” may not expose properly

creating either a too dark, or too light image

By using the camera’s meter, you can decide the

proper exposure and adjust for it

What creates this shadow?

Body Nomenclature Single or Continuous Shooting Mode Menu White Balance/ Help/Protect Playback ISO/Thumbnail Image Quality Body Nomenclature Single or Continuous Shooting Mode Menu White Balance/ Help/Protect Playback ISO/Thumbnail Image Quality Body Nomenclature Zoom/Thumbnail/ Zoom Playback/Help (Optical vs Digital) Multi Selector Delete Auto/Scene/ Movie Menu Flash Mode Self-Timer Macro Playback Flash Lamp – Indicates Ready Status Body Functions  Hot Shoe / PC Socket  Hot shoe is on top of camera  PC socket is usually on the side or front of camera body  Self Timer  Pentaprism  is a five-sided optical glass element that reflects light Body Functions  Mirror  Directly behind the end of the lens that attaches to the camera body. Covers the shutter or sensor and allows camera user to see through the eye piece and look directly through the lens for a “what you see is what you get.” Body Functions

• Shutter
  • Traditional type was a curtain made of cloth. Modern cameras use blades made of aluminum alloy, carbon fiber or titanium that blocks the light that comes through the lens. The shutter opens and closes at a preset amount of time called shutter speed. Usually found at the back of the camera, just in front of the film.
  • With digital, you may have an electronically controlled shutter or a combination of mechanical shutter and electronic sensor that turns on for a specific amount of time.

Body Functions - Image Sensor Size Film has been replaced by a microchip with microscopic transistors. Millions of transistors create the chip that is the image sensor. The larger the sensor, the better the quality. As the sensor is made smaller, a multiplier is used to replicate a normal (cropped) view or normal perspective. APS-C is multiplied by approx 1.5x. Field of view/Perspective Full size sensor vs. Smaller digital sensor 35mm or higher end on most of the DSLRs DSLR 35mm lens with APS-C smaller sensor

50mm lens with Full Frame camera

In order to replicate a “normal” view or perspective, a “full frame” camera would use a 50mm lens as shown above With a digital camera that has a smaller sensor, you would use about a 35mm lens as shown below. 35mm x 1.5 = 52.5 (close to 50mm) If you don’t compensate for the smaller sensor, you will have a cropped effect 50mm lens with Full Frame camera 50mm lens with smaller sensor. Notice the cropped, or enlarged image Body Functions  Camera modes  Different cameras have different modes available  Scenes (could be programs for action or portraits indicated by icons of a runner or woman’s face)  Shutter Priority  Aperture Priority  Manual  Automatic  Program Body Functions  Lens Release Button  Focus  Auto  Manual

Auto Focus vs. Manual Focus  Auto focus works well and quickly in bright areas  In limited lighting, the camera may not let you take the photo if the camera can’t focus  Manual focus will generally be best for close up work and especially where limited light is available  Manual also works well for moving objects if you can pre-focus on an area then take the photo as the person or object moves into the area, such as surveillance and sporting events

Common types of flash memory

cards for digital cameras:

Compact Flash Secure Digital (SD) xD-Picture Card (^) Memory Stick Size of memory Memory cards come in different storage capacities, ranging from 8MB all the way up to 64GB and beyond. How many photos can a card hold?

• How many digital photos the card can store depends on the resolution (megapixels) of your camera, the quality of image, and file size you choose.
• The higher the resolution or megapixels, the larger the file size and the more memory each photo uses.
• Many SOP’s recommend using the highest quality images for crime scene and evidence such as RAW
• Some labs require RAW files for comparison work
• Otherwise use higher quality JPEG images In addition to resolution, the capacity also depends on the combination of image quality and image size  RAW 135 N/A N/A  JPEG Fine 285 495 1000  JPEG Norm 552 940 1800  JPEG Basic 1000 1700 3100  RAW + Basic 119 N/A N/A Using a 1 GB card in a 6.1 megapixel Nikon D camera, the following chart indicates the photo capacity Printed image size: Large Medium Small 15”x10” 11.5”x7.5” 7.5”x5” The combination of image quality and image size can be selected in the menu or external buttons  Causes camera to under or over expose your subject to match lighting conditions Exposure compensation

Exposure Compensation EV - 2 EV + EV 0 EV - 1 EV + Please turn your exposure compensation back to the zero setting for future exercises Shutter Speed  The AMOUNT of TIME the shutter is open or the digital sensor is on, allowing light to strike the sensor  Combined with aperture & ISO for proper exposure  Generally measured in fractions of a second  1/60th^ (indicated by the number 60 , or 1/60)  1/125th^ (indicated by the number 125 , or 1/125)  May be seconds or even several minutes long  1 second (usually indicated by 1” or different color)  30 seconds (usually indicated by 30” )  “Bulb” is used for time longer than 30 seconds Shutter Speed  Controls Motion  Fast shutter speeds “freeze” motion  Bullet being shot from a gun  Race car “stopped” on the track  Sporting events  Slow shutter speeds “blur” motion  Car’s taillights shown at night as a long red streak behind the car  On bright sunny days, you have the chance to over- expose your photos, or wash them out  In order to reduce the amount of light getting to the digital sensor, use a faster shutter speed  Change from 1/60 or 1/125 of a second, to a faster speed of 1/500 or even 1/1000th^ of a second  Flash Synchronization Speed  Generally about 1/60th^ Second  May be higher depending on camera (1/125, 1/250)  Too fast of a shutter speed can cause part of the photograph to be cut off Shutter Speed Shutter Speed

• May be set by a dial or combination of buttons and/or dials - 60 actually means 1/60th^ of a second - Shutter speeds will be displayed in the control

panel, viewfinder, on the monitor or a

combination of these

Some speeds can get confusing

between 1/8 second and 2 seconds

.125 Seconds .166 Seconds .20 Seconds .25 Seconds .33 Seconds .4 Seconds .5 Seconds .625 Seconds .77 Seconds 1.0 Seconds 1.33 Seconds 1.6 Seconds 2.0 Seconds

Shutter Speed shown on camera

Aperture  F/stops  A specific sized hole that is controlled w/in the camera lens  Allows a specific amount of light through the lens to the sensor  The larger the opening, the more light gets in  Controls Depth of field

F

F

F

F

Larger opening (lower number) allows more light

Depth of Field  The area of the photograph before and after the point of focus that is clear and sharp  Controlled by the aperture  The larger the opening, the less depth of field  The smaller the opening, the greater depth of field  It becomes more critical on close up photography such as fingerprints on a curved surface such as a light bulb or door knob

F-4.

F- 8

F- 16

Depth of Field  The point of focus can also affect the depth of field  Balance depth by using the “rule of thirds” which means to focus one third of the way through the scene

The closer to the object, the more

important depth of field becomes

F-5.6 F- 36

Close up of fingerprint on light bulb F-4.8 F- 40 Film/Digital Sensitivity ISO – Film speed or the digital equivalent  Film speed/ISO is the sensitivity to light  The lower the ISO number, the less sensitive to light  The higher the ISO number, the more sensitive to light  100 speed film is less sensitive to light and needs MORE light to be properly exposed than does 200 speed film

• The more sensitive to light , the more grainy it gets, generally lowering quality
• ISO 100 produces better quality than ISO 1600 ISO Changes: How Much Does It Affect Quality

ISO 200 ISO 1600

ISO 200 ISO 400

ISO 800 ISO 1600

Canon Metering Modes Evaluative: All around averaging Partial: Good for backlighting Spot: Specific small area Center-weighted: Metered at center then averaged

Metering can be adjusted with an

external button or in the menu

Nikon Canon

Where’s the

gun?

There it is!

Camera used with automatic setting is fooled by the light sky in the background and creates a dark subject. Instead, use the camera’s meter to sense the area in the shadows for proper exposure

Some cameras have histograms

viewed on the rear monitor

Dark tones on left Light tones on right missing

Some cameras will have

only a brightness histogram

shown in white. Others

will have a histogram for

each of the red, green

and blue color channels

Information available about the captured image during review or playback

Flash Modes  Front-Curtain Sync: used for most situations. In “P” and “A” modes, shutter will be set automatically between 1/250 and 1/60.  Slow Sync: used with slow shutter speeds up to 30 seconds. Captures both subject and background at low light.  Rear-Curtain Sync: Flash fires just before shutter closes.  Red-Eye Reduction: Flash pre-flashes before main flash.  Red-Eye w/Slow Sync: Combines both. Flash  The further an object is from the flash, the less light the object will receive to be properly exposed  Light intensity drops off very quickly Flash Technique Best if flash is off camera The angle of incidence is equal to the angle of reflection. If slightly angled, there is little or no glare or wash out reflection in the photograph. Bounce flash can also be used. Direct - can result in wash out Flash Technique  Bounce  May bounce off of ceiling, wall, floor, any object  Must allow for one stop correction  Light fall off occurs due to the distance that the light has to travel. You will probably have to adjust by an F-Stop and or increase the power of the flash

Direct flash

Bounce flash –

ceiling

Bounce flash

with reflector

card

Bounce Technique

Flash Technique  Diffused  A translucent filter is placed over the flash to diffuse or break up the light and give it a softer look  Fill Flash  Used to add light to shadows No Flash used Fill FlashFill Flash

Flash Technique – Impression Evidence

 Use flash at different angles/heights

 3 Dimensional footwear and tire impressions generally require from 0 to 45 degrees of angle  The deeper the impression, the higher the angle  Take multiple photos with low, medium and high flash positions from all four sides  Can be used for tool impressions, latent prints, bite marks and injuries

More detail just by moving the flash position

3 Dimensional Footwear

Flash directly above impression

3 Dimensional Footwear

Flash from bottom

3 Dimensional Footwear

Flash from top

Heal section Front of shoe impression Camera set up How to create shade

Scale must be at

the correct depth