I found this really nice Zeiss Ikon Nettar folding camera in a second hand shop, I paid 80SEK for it and I did not expect it to work. After some cleaning and calibrating of the optics I wanted to find out if the different speeds of the shutter were within reasonable range. I came up with the idea of using my wife’s headset microphone. I let the microphone rest on the lens, and while recording the audio, firing off the shutter at the different speeds of the camera. The audio file was then opened in an audio editor, in this case Audacity, and the waveform for each shutter speed inspected and measured against the audio editors timestamp. My 1950s Nettar performed with a deviation of 10% from stated shutter speed, which probably is within the Vario Shutter’s manufacturing tolerances. German engineering at it’s finest.