How Carl Zeiss lenses are stress tested

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Another short video on how Carl Zeiss do their stress testing on their lenses. My favourite is where they heat the lens up to 70 degrees Celsius, then cool it rapidly to -40 degrees Celsius and then heat it up to 55 degrees Celsius again and make sure that it is still intact and able to function properly.

http://www.petapixel.com/2012/04/02/how-...ess-tested