Onboard Stills Cameras DIY Camera Payload Construction The shoot switch actually performs 2 functions: (1) focus lock, when the switch is depressed half way down, and (2) shoot, when the switch is pressed all the way down. The following will provide a step to step guide for how to build your own APS camera payload for rockets: Step 4: Modify the shoot switch This photograph shows the circuit board on which the the switch is located. The switch is operated by the pads in the centre of the image. The two tracks going to the lower right, go to the light level sensor (a simple Cadmium Sulphide Light Dependent Resistor). On this photograph, the circuit board tracks have been highlighted to illustrate which tracks are relevant for the switch. As can be seen, there are only three tracks which are relevant. These are the tracks to which 3 wires (1 wire for each track) need to be soldered to. Copyright 1996-1999 Richard Osborne, All Rights Reserved.