Setup

          We placed a fish tank on a wheeled platform, and placed a thick piece of glass in the center of the bottom of the tank.  We then filled it with water, then with a layer of vegetable oil.  We covered the open top of the tank in plastic sheeting to prevent water or oil from splashing back into the barrel of our gun, the RWS Diana, and altering the speed of the .177 RWS Superpoint pellets, which would presumably decrease the accuracy of our data.  We then aligned the tank under the gun barrel, with the gun mounted vertically, firing downward perpendicular to the bottom of the tank.  The gun was mounted on a wooden frame.  We lined the gun up with the thick plate of glass in the bottom of the tank to prevent the pellets from shattering or cracking the thinner glass of the tank bottom.  We taped our Vivitar 283 flash units into paired banks, which opened outward, allowing for easy positioning, and replacement of batteries.  We placed these in and on top of the box to the left of the tank, as seen in the diagram illustrating front view.  We placed two flashes above the line of oil, with two more facing into the oil and another four aligned with the water.  We placed a reflector across from the flashes, on the other side of the tank.  This reflected light from the flashes directly back into the liquid.  We secured our sound trigger to a shelf near the frame supporting the gun, but not directly to the frame.  This prevented incorrect triggering due to vibrations in the frame of the gun.  This trigger was connected to an amplifier, which was connected to a gameport interface on the Apple II+ that we used as our intervalometer.  We connected output from the gameport to the optoisolator used to trigger the flash units.  It also allowed us to deactivate or activate flashes as needed.  We placed this array of triggering equipment to the left of the tank and gun, beside the flashes, on a cart.  We hung a backdrop behind the tank, to cut back on glare from the wall behind the clear tank.  We secured the camera to a mini-tripod approximately 0.25 meters from the path of the pellet, and elevated it on several blocks to better capture a view of the tank.

Diagrams

 

Front View of Setup (excluding camera)

 

Top View of Setup