Method and Setup

Equipment:

A:  Milk bottle with stopcock

B:  Ringstand (5)

C:  Rotator

D:  Inverted Bowl

E:  90 degree clamps (6)

F:  Plastic Sheet to catch milk spray which drains into a tub

G  Photogate

H: Vivitar 283 Flash unit

I:  Delay Unit

Arbitrary Additional Equipment

Tripod, clamps to secure things, lab table

The cameras used were the Sony DKC-FP#3 and the Nikon D1.  In the diagrams, the side view is from the view of the camera and the black arrow represents the positioning of the camera in the overhead view picture.  Camera was mounted on a tripod for the entirety of the photographing sessions.

Experimental Setup:

            To set up this lab, I placed the rotator on a table.  I then placed the bowl on the rotator and used a pencil while the bowl was spinning to center it.  After that, I used hot glue to secure the disk to the rotator plate.  Then, I set two ring stands on either side of it which I bridged at the top using another piece of a ringstand and 90 degree clamps.  I attached the milk bottle, with stopcock, to the cross bar with a 90 degree clamp.  The tube of the bottle at the neck is similar in diameter to the ring stand bar so the 90 degree clamp worked nicely.  The 90 degree clamp was omitted from the diagram so as not to clutter the milk bottle and photogate region.  Next I attached the photogate to an arm with a clamp which I then attached to the third ringstand using another 90 degree clamp.  I positioned it under the bottle with stopcock and connected that to the delay unit which sat on one of the ringstand bases.  Using the existing three ringstands and two additional ringstands, I placed the piece of plastic around the entire setup to catch the milk spray coming from the bottle.  I sealed it at the base of the rotator and had it drain into a plastic tub.  The Vivitar 283 was attached to a hat/coat stand from the lab for convenience, but it should be noted that the angle of the flash was from approximately 65 degree above and 40 degrees from the camera line of sight.  The camera was placed on a tripod for stability and convenience.

Method and Timing:

            My goal of this experiment was to first observe the effects of rotation on the splash, and then, as time permitted, vary the rotation speed and the radius of splash position.  After all the equipment was set up, plugged in, and the milk bottle filled, I turned on the rotator and adjusted the RPM until a relatively rapid but stable level of rotation was obtained.  I then turned the stopcock until drops fell with a period of about 1.5 seconds (because the camera was set with a 1” shutter speed).  Then I would adjust the delay to the desired stage in the splash.  Then I would turn off the lights, watch the drops fall from the nozzle of the stopcock.  Just as the drop began to disconnect from the nozzle I would press the shutter release button on the camera which would give just the right time to capture the picture (although I had a 1” window, I used the method the entire time because it worked very well and was simple.)  I would then turn on the lights.  After that I would either stop the drops and the rotator and adjust the position of the rotator rpm or adjust the delay of the flash to observe a different stage of a splash and then continue with the open shutter method of taking pictures.  When shooting with the Sony, I used maximum optical zoom, a sensitivity of ISO 400, and a resolution of 1344 x 1024.  When shooting with the Nikon D1, I used a 50mm fixed focal length lens and an ISO sensitivity of 800.