There are many different ways of taking an great close up or indeed a shot that looks like a macro, without anything more than an ordinary, cheapest 50mm 1.8 lens for instance. It's important that you have this lens, both Canon and Nikon make a 50mm prime that is sharp as a razor and most photographers can afford it. The rest is technique.
I’ll start with the cheapest, and we can say, cheating option:
Macro purists will tell you that you are not shooting macro unless the subject that is about 36 mm across fills the frame. But if you think about it, who cares whether your picture is technically a macro? If it looks like a macro, it’s the beauty of art that matters. Majority of macro clubs have closeup galleries so it really doesn’t matter to which gallery you submit, what’s important is the photograph. This is one of my severe early crops, taken without macro lens or a flash but using a tripod and low ISO
Droplet here is quite big, but if you only want closeups, there is no reason at all why you need a macro lens to get the shot you want good enough for a crop later. The biggest problem with cropping though, is resolution loss and noise, and indeed, there is only so far that you can push this.
But there are two things you can do when you get close as possible, and these are really helpful in shooting any kind of macro - enough light and a steady camera. Unless you have a lot of light, really steady hand and perhaps a really awesome lens with vibration reduction, most of the time you shoot macro you will need a a steadying device such as a tripod. While small blur in non-macro pictures is no bother most of the time, it positively ruins a close shot, so you must be meticulous about steadiness.
As far as light goes, the noise shows up in shadows so it's very important to have a well lit scene and if you need shadows for your artistic purposes, you must drop the ISO as low as it will go, because higher the ISO – the more noisy shadows will be.
As you see, already you are lugging a flash and a tripod as well as your camera on your back, macro business can be physically demanding, but there are very few things as satisfying as an excellent macro photograph, so don’t worry, you’ll get used to it. If you only have on-camera light, have a look at this awesome tutorial on how to make your own flash extender – all you will need is a carton of milk and your lighting will improve beyond recognition, lending a much better quality to all your close pictures.
REVERSING THE LENS
This is also a cheap way of getting awesomely close, and many insect photographers love the results as you get a really interesting depth of field. You need to get used to it, but if you want a macro lens on a cheap. Your 50mm prime can double as a macro lens, perhaps with no more than few pounds worth of a reversing ring and simple instructions.
Fly by Framed by Nature
My least favourite but truth be told, I haven’t used them much. Some people love them, but usually thay have more expensive ones, made by Nikon or Cannon, and one of those will set you back as much as a full set of extension tubes (see below). Having said that, some people use them with such stunning results that they are a much better source of information. For starters, have a look at this picture which was, as most of her macro work, shot with macro filters:
Candy by Jules 1983
and then, visit her gallery to get the better idea of the fact that everything is a personal preference and in the hands of an artist, there are many different way to achieve absolutely stunning results.
But on a basic level, these are simply magnifying glass filters that screw on a lens like any other filter. They enlarge the subject but because they add yet another layer of glass between a subject and the sensor, often, but not always, they result in less than satisfying pictures which are soft or even blurry. Also, filters or not, you still need that light and a steady camera.
My favourites are Kenko extension tubes. The reason why they are so good is that they have electronic connections so they will respond to changes in aperture just like a lens would. You mount them in any combination between your camera body and the lens, and I find they work best with prime, not zoom lenses, which brings us back to our cheep and awesome 50mm 1.8.
Extension tubes are essentially hollow tubes/rings which extend the distance between the camera and the lens thus enlarging the subject, but without adding a layer of extra glass, so they will not additionally blur your pictures. But also, extra distance means less light, so you will need more light if you are shooting with tubes then if you are shooting without.
Even though I have a macro lens, I use the tubes all the time, sometimes with my 50mm prime and sometimes with my macro lens, if I want to get really close.
I can try to explain focal distances, but it is all academic, you simply need to try and experiment with them, and get a feel for how many tubes you want to use at once in which situation. Their camera connection comes in many forms, so when you are buying, make sure that if you have a Nikon, you buy the version for Nikon, if Canon- a version for Canon etcetera. If you are interested in more results, have a look at my gallery of droplets, almost all macros are shot using some combination of extension tubes and either 50mm 1.8 or 90mm 2.8 1:1.
They really look like any other high quality macro, and you will be able to achieve 1:1 ratio just with an ordinary 50 mm lens and a full stack of Kenko extension tubes, so no macro lens is needed after all.
This option needs no special introduction, a good 1:1 macro lens is as fabulous as it is expensive, but at the end of the day, you still need your light, tripod and probably extension tubes if you want to get super-close. One of the best and the cheapest macro lenses which I use for all my macro work is Tamron 90mm 2.8 1:1 but I hear that Nikkor Micro 105mm 2.8 1:1 VR or Nikkor 60mm 2.8 1:1 are also awesome. I am a Nikon girl, but Canon and Zeiss also make terrific and comparable lenses so all you need is to search for “macro lens” and your type of camera and you’ll be spoilt for choice.