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Page 1: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Emissivity of White Camera Lenses vs

Black LensesLandon Hansen Trey Mortensen

Page 2: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Background• Canon claims that the white paint keeps the

camera lens cooler than the black paint• Helps protect thermally sensitive components • Used on large lenses ($$$$$)

Page 3: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Objective• Observe if the white paint is actually effective in

heat reduction and determine by how much• Compare measured results to theoretical work

Page 4: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Experiment• Two lamps in a large room at constant temperature

• Lens sat under lamps for 4 hours

• Measured the initial and final temperature with an IR thermometer

Assumptions• Steady state is reached

• α and ε based off of similar paints

• Inside temp is constant

• Only Natural Convection

• T∞ is Constant

• Lamps are equivalent to the sun

• For qbulb, use the wattage of the bulb

Page 5: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

ProcedureG (Irradiation)

E (Emmision)

qconv (Free Convection)

T∞

Page 6: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Results Experimental

Dataα ε Initial Temp

(°C)Final Temp (°C)

White Lens .3 .887 16.0 18.8

Black Lens .956 .86 16.0 18.9

Calculated Results

α ε Initial Temp (°C)

Final Temp (°C)

White Lens .3 .887 16.0 33

Black Lens .956 .86 16 21

Page 7: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

Conclusion• The white paint does remain cooler

• Calculation - Approx. 10°C difference• Measurements - .1°C difference

Sources of Potential Error• Nusselt Number assumption

• Assumed vertical cylinder

• α and ε were not measured but assumed• Noise based off of small temperature change• Assumed all white/all black lenses (no rubber grips)• Unknown exact lens dimensions

Recommendations• Stronger light source • Actual measured α and ε • Better controlled Environment

Page 8: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

AppendixEmissivity and Absorption Table

Wiki.naturalfrequency.com/wiki/Absorptance_and_Emittance

For properties, derivation of equations and details of solution, see scans

Page 9: Emissivity of White Camera Lenses vs Black Lenses Landon Hansen Trey Mortensen

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