I might be wrong, but "extension tubes" are probably the way to go. I know "tele converters" are for extending long lenses, so I think extension tubes is what you'd need. I've made do with a cokin magnifier, cheaper, but it was ok. I noticed is suffered slightly from chromatic aberrations, and softness (which in one case was pleasing).
Otherwise, consider a real macro lens. I've produced a page on it here: Macro Photography, as elsewhere in the internet it's been asked before, and this page has been of help for others.
I second winjeel. Extension rings are theway to go for macro. They reduce your focal distance and DOF drastically. Teleconverters double (or 1.4'le) your focal length thus providing a magnified image with some light fall off.
A set (usually 3) of AUTO extension tubes is what you need. This will allow the auto diaphragm mechanism to operate normally. I would use your lens @70mm rather than at the wide end. This will give more distance between lens and subject. DOF is very limited and normal focusing is not the best way. Instead, decide on your approximate subject area by experimentation, set the focus to infinity and move the camera towards the subject until the image is sharp. I wouldn't advise using the lens shorter than 50mm for macro work but between 50 and 70 you should get some good results. Using tubes will result in reduced exposure and this will depend on the amount of extension and degree of magnification but TTL metering will automatically take care of this. Get some tubes, shoot some pictures and you will discover a whole new set of problems to solve like camera shake, tripods, flash etc. but feel free to come and ask.
P.S. Try the Macro Forum .
Last edited by Allan Swindles; 03-25-2009 at 06:27 PM. Click to view previous post history.
I'm into painting with light - NOT painting by numbers!
Kind of to make things a little clearer for you, you should expect to get top quality results from a dedicated macro lens; second to that using extension tubes; thirdly a Cokin magnifier; lastly, a magnifying glass.