So next you need to get your pictures closer to the drop. They are quite small so you need to get into the Closeup -> Macro Range.
1). Macro Lens
Easily the best choice BUT it comes at a price. Basically these are lenses that focus closer than normal and allow you to get bigger images on your sensor.
I have used a 100mm Canon, 180mm Canon 'L' and a 70-300mm Tamron Zoom lens. For your money the best out of those is easily the 100mm canon. With a 20cm working range at 1:1 magnification it's super sharp. (it also focuses REALLY fast which is not useful for drops but means you can go out and shoot insects with it too!).
180mm Lens is amazingly sharp, great lens but at a price. 3-4 times the price of the 100mm lens and VERY heavy.
The Tamron zoom macro is the cheapest (came with my camera for £100 and you can get cheaper on ebay) BUT.. to get to half the magnification if the 100mm macro you need to have it 92 cm away!
This was taken with a 100mm Canon Macro
2). Extension Tubes
I've never used extension tubes on my canon lenses because they are quite expensive (about £100) because you need to get the ones that preserve the aperature control with your lenses. HOWEVER there is a cheaper option...
1 M42 adaptor from ebay (£10)
1 set of M42 Extension tubes from ebay (£10)
1 50-55mm m42 Lens from ebay (£5-£20)
I have used this setup for a large chunk of my pictures and you can get some really good results for less than £40
This was taken with a 55mm M42 lens and 1 12mm Extension tube.
The Rest of the Options
I've not really used these options but they can be worth a go :
1). Closeup Lenses
Beware of the cheap ones on ebay.. If you want good results you probabily need to pay a little extra.
2). Reversing a lens
You can buy a reversing ring to mount a lens backward on your camera to do macro. Never done it!
Last Option.. Dont get close.
The following pic was taken with a standard 50mm f/1.8 Canon lens (the 'nifty fifty') and it remains one of my favorite images.. You dont *have* to get close to get good images.. but it helps :)
Next : Lighting!