The converters create some nasty distortion depending on the quality, so you might want to recheck getting one of those.

I use a Telex 1.5 w/my 17mm, and it's cheap enough to use as my lens cap, the little original one is long lost, and it still fits in my leather Olympus camera case. I find my self using it all the time especially in rooms. It does distort on the edges, perhaps I should look into a better brand or something. They are cheap, get one. I use it all of the time, maybe too often.

Could you upload sample images (particularly, tripod-mount the camera and take two pics with all the same settings [well, 'cept focus likely], one with the converter and one without so we can see the diffs)? A friend encouraged me to get a macro or zoom converter to play with but the reviews I've seen were very anti...But I haven't seen good examples of how they affect image quality.