Close ups

A dedicated macro lens would be the most obvious and easiest route, but expensive (unless you don't mind manual in which case you can pick up some good second hand deals on the usual auction sites).

There are also cheaper options though;

1/ Extension tubes - hollow tubes that go between the camera body and the lens, increasing the distance between the back of the lens and the sensor, which in turn allows you to focus on objects closer in front of the lens. More expensive tubes will convey the signals between camera and lens so you can still let the camera work out the correct exposure. Cheaper extension tubes have no electrical connections and you'll need to use manual settings to expose correctly.

The key benefit of extension tubes are that the simple ones are very cheap but effective, with no loss of image quality introduced as there's no glass in them. The drawbacks are that you will probably need to shoot manual and they will cut the amount of light entering the camera, meaning you'll need to use a larger aperture, higher ISO or longer shutter speed. Some lenses work better than others converted into macro mode with tubes and they really need an aperture ring on them which you can adjust manually - not all have this, particularly modern consumer zooms.

2/ Diopters - magnifying lenses that you screw onto the front of your lens and magnify the image coming in. The key benefit is they're extremely simple to use and you can operate your camera in exactly the same way you would normally. If your aim is to get the best quality 'printable' photos, avoid the cheap diopters that are available - they do work but will decrease IQ.
Raynox have a good reputation for producing some good quality dioptres, a bit more money but probably worth it.

3/ Reversing rings - threaded adapters that enable you to mount a lens onto your camera back to front, enabling it to focus much closer. Some lenses work better than others for this and it's a manual only deal, but it's a very cheap experiment to try. You can also reverse mount a prime lens onto the end of a longer lens with an adapter and use it like a diopter.

At one stage for high magnification shots I was using a macro lens on extension tubes with another lens reverse mounted onto the end of that - not very portable!

What 500 do you have (just out of envious curiosity)?

Canon's 75-300 doesn't have the hottest reputation, but a good 70-300 lens is suitable for use with either diopters or extension tubes. Kenko sells electronic extension tubes, that are relatively cheap, and will allow electronic functions (aperture and AF), though you will likely want or have to manually focus at very close ranges. You have to have electrically enabled extension tubes to use with a Canon EF lens, all (normal, non-wacked out) EF lenses have an electronically actuated aperture mechanism, which needs an electronic connection to the body to function.

Reversing rings tend to work best with a good prime lens, old manual focus FD or Nikkors can be had for cheap, and will work fine, given that you will be all manual with a reversing ring, you'll need a doohickey to actuate the aperture lever, though. You can also reverse a complete lens on the front of a longer lens, it will act as a really powerful screw in diopter.

Relatively good Macro lenses can be had starting in the ~$450 range (Tamron 90mm). Longer (focal length) is better for shooting stuff outside that you want to be as far away from as possible (like bugs that will run from you), but you don't want too long a lens for shooting indoors in more cramped space (my Sigma 180mm Macro is way too long on a crop camera for shooting frog sized stuff indoors).

I enjoy my canon 100mm macro.











Im poor so it doubles as my zoom lens as well.