As rfusca mentions, the quality of "macro filters" (more correctly termed "close-up filters/lens") are generally low, but there are a few that are generally well-liked. The key is to find achromatic offerings, which use more than one piece of glass to combat aberrations, and are fairly high quality. Much like the el-cheapo std close-ups, they can be had in a variety of "dioptres" (magnifications) There are a few options that I know of:
1) The canon 250D(+4 dioptre) and 500D(+2) (not to be confused with the camera of same name) screw on lenses are great, and can actually be purchased in a range of sizes. Bryan Peterson swears by his.
2) The discontinued Nikon xT range of dioptres (2T,4T,etc). These are hard to find and can be costly, but are of similar quality to the Canon offering.
3) Marumi achromatic close up. I don't know squat about these, but they come in different sizes and magnifications, and are well liked around the 'net. You can get them on ebay relatively cheap, and there is a dedicated flickr group for owners.
4) Raynox DCR-xxx series. Many like the DCR-250(+8 Dioptre), but I actually own a DCR-150 (+4). Sometime's I find even that is too much mag. For nice "close-ups" like Bryan shows in his videos, don't go higher than +4 (This is simplifying matters somewhat. Obviously, the lens you are using it on is a factor as well, but generally speaking, the higher the dioptre rating, the closer to true 1:1 and beyond). Go higher if you want to get crazy reproduction ratios.
The only caveat to the Raynox lenses is that they are only technically 43mm. That means they can vignette on larger glass, especially at wider zoom ranges. I use mine on a Nikon 55-200VR (52mm thread), and it's great throughout the range.
Reasons to use these in lieu of extension tubes/reversal ring:
- Can be added/removed without removing the lens, and exposing the
- Extension tubes are more effective with shorter focal lengths, where
as close-up lenses are better on longer lenses.
- No change to effective aperture.
- Retain AF and CPU control over the lens (extension tubes that do this
are much more costly than those that don't).
- Still relatively cheap.
The reality is, quality images can still be made with these. Kenko tubes would have cost me more than double what I paid for the Raynox. Everything has it's place.
Since it seems that these are unpopular around here, I'll provide a sample:
Nikon D90, 55-200vr @ 200mm, f/16, 1/60s, ISO200 + Raynox DCR-150 close-up dioptre.
This is an SLI connector, and is about the width of my thumb.
See also: http://blog.instantkamera.ca/2012/03/hot-stuff.html for another image w/ context on the pictured area.
The dioptre + lens were no more than $200 total.