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 ($$$$$)

Objective Observe if the white paint is actually effective in heat reduction and determine by how much Compare measured results to theoretical work

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 q bulb, use the wattage of the bulb

Procedure G (Irradiation) E (Emmision) q conv (Free Convection) T∞T∞

Results Experimental Data αεInitial Temp (°C) Final Temp (°C) White Lens Black Lens Calculated Results αεInitial Temp (°C) Final Temp (°C) White Lens Black Lens

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

Appendix Emissivity and Absorption Table Wiki.naturalfrequency.com/wiki/Absorptance_and_Emittance For properties, derivation of equations and details of solution, see scans