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The Yashica Partner is a cheap 35mm viewfinder camera made by or for Yashica in Hong Kong from about 1983 to 1986, also sold as the Perca Crest. It has an 38mm f/4 lens with fixed focus and a single shutter speed. It also has a builtin flash driven by two AA batteries which can be activated and pre-charged by a switch on the back. The front folds up and retracts the lens.
A gear on the lens controls the aperture, ranging from f/4 down to f/22 approximately (5 click stops). The exposure is set by selecting sunny, partly sunny, or cloudy symbols on the aperture ring or distance symbols for flash exposure. A red LED in the viewfinder will illuminate if flash is needed. A selector on the barrel adjusts the scales and the LED indicator for two different film speeds, 400 and 100. The aperture range suggests a shutter speed of around 1/100th (i.e. cloudy for ASA 100 is wide open at f/4) but measurement on one sample was closer to 1/36th.