Octorber 18, 2017: Pluto Trigger and Valve: How to determine timing and achieve high yield results.

The Pluto Trigger is quite a versatile device.  Controlled by a phone app you have all the versatility of camera sensors and Pluto software at your disposal.  One of the major challenges I had was taking photos of colliding drops of water.  While the instructions were pointed in the right direction, I was unable to get a high yield of interesting photos.  I decided to go back to basics: take a video of the drop release, splash, rebound (worthington jet - looks like a chess pawn) and collision events, measure the time of each event and then use these timings as guide for setting up the flash delay, drop 1 size, drop 2 delay and drop 2 size.

I used the VideoPad editor  to figure out the timings.  WIth the audio track, you can see all the "sounds" associated with the Pluto drop application

1. The beep from the phone app
2. The sound of the water solenoid opening for drop 1
3. The sound of the water solenoid opening for drop 2
4. Camera (flash) activation - I'm using a Nikon 7500 and there is an internal delay between activation and the actual flash.

Here is a slow motion video of the 2 drop sequence: A 2 drop, 40 sec (slomo time) = 5 sec (real time) delay to allow the bath to return to a quiet surface, then another 2 drop sequence

iPhone slow motion video (240 fps) of the drop dynamics

GoPro slow motion video of the drop dynamics (720p, 240 fps)

Here are the details showing what the camera sees:

1: The red cursor is aligned with the Pluto app "beep" (the image is from the previous collision) 

The red cursor is aligned with the 1st drop release (the image is from the previous collision)

The red cursor is aligned with the 2nd drop release (the image is from the previous collision)

The red cursor is aligned with camera activation (previous image went to sleep)

The red cursor is aligned with the moment the flash appears on the camera screen: the result of the 2nd drop drop colliding with the Worthington jet associated with the 1st drop

Video of a sequence of drop collisions - illustrating the variability associated with the same timing parameters.

Calibrating Drop Dynamics:  time to splash, time to max rebound and flash.  Slow motion: 240 frames/sec

Single drop released, splashes and rebounds

Two drops released with a delay of 90 msec.  This delay approximates the delay necessary to produce a collision between the first drop rebound and just before the second drop splashes

Drop release, camera / flash trigger and resultant image on the camera LCD screen