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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

- 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

Measure the blur angle (q ) with a protractor

- 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.

- 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

- 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

- 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;

- 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

- 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.

Snap to release lens assembly

Capacitor

Capacitor leads

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

Spring tab connected to circuit board

Contact between shutter and bar completes flash trigger circuit

Brass bar connected to circuit board

- 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.

- Read Camera Lab 2 materials CAREFULLY!!