I am a photography newbie and have only a 18 - 135mm canon kit lens at my disposal. I wanted to take macro shots but can't really afford a macro lens right now. One very optimistic goal of mine is to capture a single snow flake this winter.
Is there any cheap(er) way to take macro shots? Also, any specific advice from anyone one how to go about photographing a single snow flake.
There are a few options to do macro on the cheap.
The most common is extension tubes which are hollow tubes that basically just move the lens further away, which decreases the minimum focusing distance.
If you're really stuck you can just hold your lens in front of the camera. Focus and composition are a bit hit and miss with this method! For more information, see Freelensing! Turn any Lens into a Tilt-Shift or Macro
Another option is to use close up filters, which are additional screw on optics that go in front of a lens to allow close-up focusing. I haven't had any experience myself, and it's not the cheapest option. For a good low-down on close up filters, you can read more at Comparison of Close-up Filters and Macro Lenses
Finally, you can mount a telephoto lens in reverse! This can be the cheapest option of all (besides freelensing) because you can make a reversal ring from a pair of lenses and body caps. However, with your 18-135 lacking manual aperture control, you'll be stuck shooting wide open.
If I were you, I'd pick up a set of cheap extension tubes and go from there! As for photographing single snowflakes, I admire people with ambitious goals, but I think you might be reaching too far here because you've chosen something seasoned photographers with many years macro experience would struggle with.
Typical macro lenses provide approximately 1:1 magnification, meaning the image on the sensor is life size. The sensor in your camera is about 22mm across so that's effectively the smallest thing you can image. To fill the frame with a snowflake you need to go supermacro, which as Shizam states is beyond these budget macro options. Depth of field is so small (like a hairs width) at these distances you need a very precise means to maneuver the snowflake into shot.
You can search YouTube for videos of people capturing snowflakes to see how they did it.
Matt has already covered a number of options, which I won't try to repeat here.
Unless I missed something, he did miss one possibility though: this is to use a relatively long lens on the camera, with a relatively short lens, reversed, in front of it. This is basically the same as the closeup-lens option Matt did mention, but instead of buying a new closeup lens to use, you use a lens you already have with a dirt-cheap reversing ring (basically, just a hollow tube with filter-sized threads on both ends).
Getting this to work well can be somewhat challenging, to put it mildly. In particular, it's often worthwhile to do a bit of experimenting with free lensing to find a combination of long and short lenses that happen to work well together, and only when you've found a good combination, buy a combination of reversing ring and (if necessary) step-up or step-down rings for that pair of lenses. Of course, it's also nice if you have two or three different lenses with the same size filter ring to use as the front element.
While this option does take more work than buying closeup lenses, it generally gives better results. A closeup lens is basically just a short focal length lens -- but the cheap ones are uncorrected single-element lenses, while the more expensive sets are two-element lenses to give marginally superior correction. Even those, however, generally have pretty poor correction compared to even a cheap 28, 35 or 50mm lens.
One other point: since you're using the front lens reversed and ignoring its normal lens mount, you do not need something that would otherwise fit your camera at all. A lot of older, manual-focus lenses work nicely, and can be picked up for next to nothing.
I started off with the Macro filters - I loved using them so much that I ended up buying a Macro lens..
My filters were about $10 for 4 different levels +1, +2, +4 and +10
Another tip could be using reverse rings, that allows you to mount a regular 50mm lens as a macro lens. I never used it myself, but know people that do and I it seems it's a bit hard to focus.
http://www.alanwood.net/photography/reversing-rings.html http://www.diyphotography.net/diy_reverse_macro_ring
Samples: http://www.pbase.com/andydunn/d70_50mm_reverse_ring_shots
You can also consider M42 thread lens (pentax or zenith) + macro rings which may be pretty cheap solution. Of course then You need to buy also M42 thread mount for You camera.
I am using it for Canon with EF-S mount, need some patience but it is really budget solution with relatively good results.
