ENGR-101 (Section 33)

Week 02: Shutter Speed Measurement

Today’s Agenda

14:00 Role CallWelcoming RemarksFun Motivation (Related YouTube Video)

14:15 Experiment 1: Extract camera flash circuit board

14:35 Experiment 2: Oscilloscope and FG setup: burst and trigger

14:55 Experiment 3: Camera flash circuit board installation

15:15 Experiment 4: Reading measurements (with cursors)

15:35 Discussion Points

16:00 Adjourn

Generation Gap: Class of 198X vs. Class of 2015+

Atari 400 (16K) – IBM XT (1 MB)Class of 1980x

Megabyte Generation

Pentium 3 (40 MB) – Multicore (GB)Class of 2015+

Gigabyte Generation

Worldwide Optical Content 103 TBWorldwide Printed Content 1,633 TBUS Broadcast Media 14,893 TBWorldwide Film Content 420,254 TBInternet 532,897 TBWorldwide Magnetic Content 4,999,230 TBWorld Telephone Calls 17,200,000 TBElectronic Flow of New Info 17, 903, 340 TB

Giga = 10^6 Tera = 10^12 Peta = 10^15

TerabyteWorld

Source: Hans Moravec “When Will Computer Hardware Match the Human Brain”, 1997

Biological evolution and human technology both show continual acceleration.The time between events continues to decrease; 2B years from the origin oflife to cells and 14 years between the PC and World Wide Web.

• 2014: Getting Lost• 2019: Libraries• 2020: Copyright

• 2030: Keys• 2033: Coins• 2036: IC cars

• 2050+: Ugliness, Nation States, DeathSource: “What’s Next” and the “Future Exploration Network”

Erosion of Boundaries in the Information Age

• Between products and services: think cell phones• Between producers and users: think social media• Between IT, comm, media, consumer electronics: think Amazon• Between IT and non-IT industries: think Walmart• Between academia, industry, disciplines, theory, applied research

1895: “Heavier than air flying machines are impossible”, Lord Kelvin

1943: “I think there’s a world market for maybe 5 computers”, Thomas Watson

1977: “There is no reason why anyone should have a PC in their home”, Ken Olsen

1981: “640K ought to be enough for anyone”, Bill Gates

48 years

34 years

4 years

What can we expect in the next 10000 years?2

• Bring camera: A disposable camera will be disassembled• Search and read about disposable cameras

• http://www.ehow.com/how-does_5031419_disposable-cameras-made.html• http://www.youtube.com/watch?v=emjm-HJAsME&feature=related

• Search how camera flashes work• http://electronics.howstuffworks.com/camera-flash1.htm

• What are coil guns and tasers?• http://www.youtube.com/watch?v=epaMq1vee_c

• What is a film ASA rating and how does this relate to shutter speed?• http://en.wikipedia.org/wiki/Film_speed• Roughly calculate the shutter speed needed for a disposable camera

Motivation for Today’s Lab

http://www.youtube.com/watch?v=epaMq1vee_c

Experiment 1: Extract camera flash circuit board

Goal: Dissect disposable camera to extract flash circuit

Step 1: • Remove battery• Pry apart front and back sides of casing• Remove film• Pry apart flash circuit board assembly

http://www.youtube.com/watch?v=emjm-HJAsME

Photograph eachstage of disassembly

Lab Notebook:

1-A: What features differentiate this camera from other similar models?

1-B: How does operation differ between disposable and non-disposable cameras?

1-C: What features lack compared to non-disposable cameras?

1-D: With film installed, what happens when the thumb wheel is rotated?Photo, Video and/or Sketch

1-E: Include photos at each stage of the disassembly

Experiment 2: Oscilloscope and FG setup: burst and trigger

Goal: Calibrate instrumentation in order to measure flash

Step 1: • Generate square wave at 100 Hz, 6 VPP, 3 VDC offset• Attach function generator to Channel 2 on oscilloscope• On oscilloscope, press “Autoscale”

Step 2: • On oscilloscope, press the “1” button• Set trigger level to 2.5 VDC

Position wavesusing horizontalknobs if necessary

Step 3: • On function generator, select Shift – Burst. Push Single button

Resulting scope display

Step 4: • On oscilloscope’s Trigger section: Mode – Auto. Push Single button

Step 5: • On oscilloscope’s Trigger section: Mode – Normal Push Single button

Observation: scope display continuously updates even if no trigger event is present. Hence, the signal will intermittently display somewhere along the time axis when you push the function generator’s Single button

Observation: scope only displays when triggered i.e. Single button pushed

Step 1: • Scope Channel 1: camera flash sensor• Scope Channel 2: camera shutter sensor

Experiment 3: Camera flash circuit board installation

Step 2: • Re-install battery• Fit camera flash circuit board on the measurement board

Step 3: • Push the camera flash circuit board button• If necessary adjust Time/Div and Delay setting to get following display

Troubleshooting: If needed, set Trigger Source to “2” and Level at 2.5 V

Experiment 4: Reading measurements (with cursors)

Goal: Use voltage and time cursors to measure flash times

Step 1: • Select Measure – Time - Cursor• Rotate knob to align first cursor. When finished, click cursor again• Rotate knob to align second cursor

Time Cursors

Step 2: • Top wave: Flash signal• Adjust voltage cursors to measure max voltage difference (delta VF) • Position V2 cursor at 0.5*delta VF• Position time cursor T1 at start voltage step• Position time cursor T2 at time where V2 intersects flash signal

delta VF 0.5 delta VF

T1Start of Voltage Step T2 Time V2 hits 0.5 delta VF

Record Delta T = T2 – T1. This is called the Flash Pulse Width

Step 3: • Bottom wave: Shutter signal• Adjust voltage cursors to measure max voltage difference (delta VS) • Position V2 cursor at 0.5*delta VS• Position time cursor T1 on the rising part of shutter signal (V2)• Position time cursor T2 on the falling part of shutter speed (V2)

delta VS 0.5 delta VS

T1Rise point for V2 T2 Fall point for V2

Record Delta T = T2 – T1. This is called the Shutter Pulse Width

Step 4: • Place V1 cursor at 0.5 * delta VS for bottom wave (shutter signal)• Place V2 cursor at 0.5* delta VF for top wave (shutter signal) • Place T1 at V1 (rising) intersection• Place T2 at V2 (rising) intersection

V1: 0.5 delta VS

T1 T2

Record Delta T = T2 – T1. This is called the Leading Edge Offset

V2: 0.5 delta VF

Step 5: • Place V1 cursor at 0.5 * delta VS for bottom wave (shutter signal)• Place V2 cursor at 0.5* delta VF for top wave (shutter signal) • Place T1 at V1 (falling) intersection• Place T2 at V2 (falling) intersection

V1: 0.5 delta VS

T1T2

Record Delta T = T2 – T1. This is called the Trailing Edge Offset

V2: 0.5 delta VF

Lab Notebook: We want 2 more trials of time data. Repeat Experiment 3 and 4

In your notebook, complete the table below with your values

Avg.

3

2

1

Trailing Edge Offset (ms)

Leading Edge Offset (ms)

Shutter Pulse Width (ms)

Flash Pulse Width (ms)

Trial

Discussion Points

Take Home Points:

• Disposable camera has fixed features e.g. fixed shutter time• Changes in shutter time will change photo’s brightness• Future labs aim to physically modify the plastic shutter• These modifications will change shutter times and hence photos

Source: http://www.increa.com/reverse/dc/

Film ASA (or iSO) Ratings e.g. ISO 100, ISO 800

• Low numbers: slower film = needs more light = longer exposures (slow shutter)• High numbers: faster films = needs less light = shorter exposure (fast shutter)

• Slow film = sharper, detailed photos• Fast film = higher contrast and grainy photos

Next Time: Week 03 – Intro to Shutter Modification

• Bring camera: A disposable camera will be disassembled• Search and read about disposable cameras

• http://www.ehow.com/how-does_5031419_disposable-cameras-made.html• http://www.youtube.com/watch?v=emjm-HJAsME&feature=related

• Search how camera flashes work• http://electronics.howstuffworks.com/camera-flash1.htm

• What are coil guns and tasers?• http://www.youtube.com/watch?v=epaMq1vee_c

• What is a film ASA rating and how does this relate to shutter speed?• http://en.wikipedia.org/wiki/Film_speed• Roughly calculate the shutter speed needed for a disposable camera