I read on a forum somewhere that if you take the lens off your camera, turn it around, and then reattach it somehow, you can make a cheap macro lens. If you have two lenses of equal focal lengths, you can put the first one on the camera normally, then attach the second one to the front of the first one, in reverse. This gives you a macro lens with an effective magnification of 1:1. I decided to give it a try today and see what happened.

This is a picture of the tip of a ball point pen resting on a lens cap. My 18-55 lens was on my camera, set to 55mm, f/5.6 and focused at roughly infinity. With my left hand I held my 50mm 1.8 reversed right in front of my 18-55. I shot this picture with my right hand holding the camera, my left hand holding the lenses together and resting on the table. The pen and lens cap are being illuminated from the left by a flashlight. It was taken with my Rebel XT at 1600 ISO for 1/30th of a second. I wound up pushing it up one stop in post because it was a little underexposed.

One thing to note about this setup is the extremely narrow depth of field that is created. You can see that even the tip of the ball point pen has parts that are in focus and parts that are out of focus, and it's less than a centimetre above the lens cap, which is winds up providing a blurry background. Fun stuff.

Comments

Cool.  David and I were playing around with doing exactly that last year. 
Turns out you can buy a 55mm reversing adaptor so you can actually attach two
lenses with 55mm threads, so if you don't mind spending about 10 bucks, its
cheap thrills :)

There are tons of them in eBay:

http://tinyurl.com/mojgv