I'd read about a macro conversion for the Canon 35-80 lens. I had the USM version and it had been dropped many times so it wasn't the healthiest thing in the world. Neither I nor my son use it so I decided to give the mod a go.
This album shows a series of images of this conversion vs. a dedicated Canon 100mm L series macro. You may be surprised at the results - I was. The 100L wins hands down for ease of use but the conversion has better magnification and with care will be useful. The one caveat is light leakage - some of the images taken by the conversion show some light that is not entering directly through the element.
All of the images in this album are straight out of camera, they have only been resized and watermarked. All images were lit naturally from the left by window light. All images were taken from the minimum distance that the lens could achieve a clear focus.
In all cases the conversion yielded better magnification than the 100L and certainly gives acceptable images.
The images I took of the lens modification process are at the end of the album. I've had this lens for a long time but a quick scan of ebay shows them available from as little as AU$10. Either this version or the non USM will work fine. The best way to hunt them down is buy it on a film camera - by itself the lens nearly always sells for more than when it is mounted on a filmy - go figure!
1. Remove the three screws that hold in the front element
2. Remove the front element
3. Carve off the filter mounting screw thread and hood ring so the front element can be reversed with a hobby knife (take care!) - you'll note that I've found the front element can be dumped - having it in gives you autofocus but less magnification.
4. Push fit the reversed front element.
5. Take pictures!