ENGR-101 Week 02: Shutter Speed Measurementpyo22/engr101-2012-2013/engr...Step 3: • Bottom wave: Shutter Pulse Width (time shutter remains open) • Adjust voltage cursors to measure

ENGR-101

Week 02: Shutter Speed Measurement

Today’s Agenda

11:00 Role CallWelcoming RemarksFun Motivation (Related YouTube Video)

11:15 Experiment 1: Extract camera flash circuit board

11:35 Experiment 2: Oscilloscope and FG setup: burst and trigger

11:55 Experiment 3: Camera flash circuit board installation

12:15 Experiment 4: Reading measurements (with cursors)

12:35 Discussion Points

13:00 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

Extra:ENGR Website: http://core.coe.drexel.edu/node/283

Lab Notebook:

1-A: Explain how the shutter mechanism works (in your own words/sketches)- What causes the film advance after the capture button is pressed?- What prevents a double-exposure of the film?- How does the shutter mechanism operate?- How does the flash circuit physically operate?

1-B: 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, 5 VPP, 2.5 VDC offset, 5 ms pulse width• Attach function generator to Channel 2Y on oscilloscope• Push Wave Gen• On oscilloscope, press “Autoscale”

Step 2: • On oscilloscope, press the “1” button (directly above input connector)• Set trigger level to 4.0 VDC

Step 1 Step 2

Step 3: • Press Wave Gen• Set frequency to pulse of 1 Hz

Step 4: • On oscilloscope’s Trigger section: Mode – Normal.

Step 1: • Scope Channel 1X: camera flash sensor• Scope Channel 2Y: camera shutter sensor• Scope or PC USB: camera USB connector

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

Experiment 4: Reading measurements (with cursors)

Goal: Use voltage and time cursors to measure flash times

Step 1: • Select Cursor. Set Cursor Mode to Manual• Rotate knob to align cursors.

Step 2: • Top wave: Flash Pulse Width (time flash remains lit)• 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 Pulse Width (time shutter remains open)• 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: • Leading Edge Offset (time between shutter-opening and flash-on)• 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: • Trailing Edge Offset (time between flash-off and shutter-close)• Place V1 cursor at 0.5 * delta VS for bottom wave (shutter signal)• Place V2 cursor at 0.5* delta VF for top wave (flash 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

Trial Flash Pulse Width (ms)

Shutter Pulse Width (ms)

Leading Edge Offset (ms)

Trailing Edge Offset (ms)

1

2

3

Avg.

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