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# Introduction To Engineering Camera Lab #2 - 2 - PowerPoint PPT Presentation

Introduction To Engineering Camera Lab #2 - 2. Agenda Open cameras, remove batteries, discharge capacitors, and disassemble/reassemble ! Sketch critical elements of the shutter mechanism Estimate Shutter speed from photos of bike wheels. Important notes:. Each group must record data

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Introduction To Engineering Camera Lab #2 - 2

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## Introduction To EngineeringCamera Lab #2 - 2

Agenda

Open cameras, remove batteries, discharge capacitors, and disassemble/reassemble !

Sketch critical elements of the shutter mechanism

Estimate Shutter speed from photos of bike wheels

### Important notes:

• Each group must record data

• Make sure one person in each group gets all the data!

• Make sure data is given to all group members

### Measuring Blur Angle

Measure the blur angle (q ) with a protractor

### Estimating Shutter Speed

• Measure the blur angle (q) with a protractor

• The radius of the wheel is r

• The bicycle traveled at 15 mph. Convert this to in/sec.

### Estimating Shutter Speed

• The amount of travel per revolution is

The angular speed is given by

If qis the blur angle in degrees, the fraction (f) of a revolution is

### Estimating Shutter Speed

• The time (t ) for the wheel to move the fraction (f ) of a revolution for a constant angular speed is related to f by:

The time (t ) is expressed in the formula:

12

(13)

t

=

= 0.010 sec = 10 milli sec

sec

,

15

100

### Estimating Shutter Speed

• The speedometer actually measures the angular velocity of the wheel axis. It assumes a wheel diameter of 26” to convert to ground speed. Therefore, use r = 13 in and assume θ = 12 deg;

### Making the Camera Safe

• Pry open the five snap fits that hold the back cover: both ends, top, bottom, back.

• Remove the back case, and take out the battery. Note battery orientation (+ down)!

• If the front cover falls off, put it back on without touching any part of the circuit board

### Making the Camera Safe

• Wind the shutter release by rotating the blue wheel until it stops.

• Press shutter release to trigger the flash.

• Take off the front case, and hand the camera to the instructor. Don’t touch anything on the circuit board, especially the small black can!

• The instructor will touch a screwdriver across capacitor leads to discharge the capacitor.

• The camera is now safe to handle.

### Front of Camera

Snap to release lens assembly

Capacitor

### Shutter Cocked for Picture

Pivot allows shutter to rotate open when arm moves to right.

### Shutter Open

Spring tab connected to circuit board

Contact between shutter and bar completes flash trigger circuit

Brass bar connected to circuit board

### Summary of Lab Steps

• Remove back of camera, remove battery, wind and release shutter/flash; have instructor discharge capacitor.

• Measure blur angle, compute shutter speed, and record value.

• Disassemble and reassemble camera with emphasis on shutter mechanism.

• Sketch critical elements of shutter mechanism.

### Assignment

• Read Camera Lab 2 materials CAREFULLY!!