I've only been dabbling with this type of photography for less than a month so this info is based purely on what I've discovered works for me. There are other deviants on dA that have spent years perfecting this type of image.
The basic setup for most of my droplet images. A second view is here in my scraps [link]
The end result is here [link]
Canon 1D MkII N and 100mm or 150mm macro lens always tripod mounted for maximum sharpness. The lens is used in manual focus.
Camera set to use mirror lockup for two reasons
a. The mechanical delay of the mirror flipping up and then shutter firing is 20-30 milliseconds so I lock the mirror up before each shot. Some but not all dSLR cameras have this feature.
b. Using mirror lockup removes almost all of the internal camera vibration, so if you can use it is recommended for a lot of photography styles including landscape/waterscape and nature photography.
The camera is in manual exposure mode typically 1/250second at f16-22 iso 100. I could stop the lens down further to increase the DoF BUT the images with the aperture fully closed to f32 are softer than at f16-22. This is common to all lens and using the maximum aperture for photography to get maximum DoF is not recommended.
Plugged into the camera is a wired cable release that runs off to the electronic delay circuit I use (more later)
On the camera hotshoe is a wireless transmitter that triggers the flashguns I use, normally Canon 580Ex guns and a 550Ex gun.
The flashgun on the right (as we see it) is fitted with a lumiquest small softbox. Ideal for general lighting and helps to soften any shadows. Again this is recommended for a lot of flash photography to remove the ugly shadows normal flashguns produce.
The flashgun on the left is covered in clingfilm to protect it
The zoom setting on this gun is at 105mm to narrow the flash coverage, giving a simple spotlight effect from behind the droplet to backlight it.
Both guns are set to manual exposure and typical run at 1/16-1/64 of full power to minimise the flash duration.
Out of shot, above the oven tray with the gold paper in it, is a bottle containing red dyed water. This water is fed down a tube into a small nozzle. This nozzle is positioned directly over the top of a laser diode and detector. When the droplet falls it breaks the beam and starts the electronic timer, which in turn fires the camera after a delay that I chose.
A few notes:
The flash duration is around 1/10,000-1/20,000 of a second and it is this light that freezes the movement of the droplet not
the shutter speed of the camera.
The ambient light of the room can cause motion blur on the droplets so subdued lighting is recommended.
A low iso setting is also used to minimise noise and to reduce the effects of the ambient light.
This type of photography can be achieved using normal high powered
studio lighting but it does need to be very high powered as you are reliant on the camera shutter speed to freeze the droplet movement.
If you have any questions/thoughts and I'll try my best to answer them.