simple way is just take a glass panel and drop a few drops of water...
as you can see, normally rain is accompanied by dark weather, so when you have fast shutter, you end up with dark image, to counter this, you need flash, but only expensive flash can do fast shutter unless its always ON, but den again, the flash cannot capture the whole scenery. and the water droplets move so fast, you can't even move your camera to follow the droplet & focus it... unless the AF is damn good.
The method i was thinking of was to just use MF and focus it anywhere you like(depending on your lens) say 1m at 85mm to get a full frame drop. Considering the number of drops all over the place you probably would get one in focus.
Could wait for rain on a sunny day It happened for 5 mins this week. It would be a real technical achievement to get a shot like this done I'd say. You'd need quite a fair bit of luck too of course
Tried taking some rain drops just now when it was raining, 1st attempt.
I think it should be easier to wait until the rain subsides, then find a spot where there is water dripping at regular frequency--e.g. from a roof onto a pool of water. The drops should be larger and at least can guess the timing.
There are many effects that you can achieve with water.
I think for rain, the best effect is to actually use a slow shutter speed so the rain drops actually look like a continious line of water. What I have done a few times in the past was instead of waiting for the rain, turn on a sprinkler on a sunny day and put a neutral density filter on my lens and take photo's of some flowers with the water coming down between the flowers and the camera.
You can also try using a flash set to rear curtin sync on a slow shutter speed.
If you want to capture individual drops of rain then obviously ramp up the shutter speed.