Macro reverse kit lens

[Aberrant]

I have a new rebel XTI, having lots of fun with it. Right now I'm playing with macro setups. I have little money to spend though.

The best setup I have so far is the 18-55 kit lense mounted in reverse. The results are less than great. I believe I can get a 1:3 ratio, a 7mm object fills the image and the sensor is 22mm. The problem is that it's blurry... also what I think is called fringing, a purple border around areas of sharp value change. Have a look, this is cropped, acrylic paint (sprayed):

http://142.165.246.187/king_face2.jpg

1/10sec, zoomed all the way in. It's in focus, the depth of field is so shallow, I just cropped to the center of the DOF. My questions:

1) Any way to get better definition at high magnification? Right now I'm concerned with as much magnification as possible, and as much clarity as possible.

2) Fringing... what's causing it, how to correct?

3) I'd like a wider depth of field. I can't control the aperture on the kit lense? I guess I'm stuck here?

4) I have an old FD 50mm F1.8 lense, need a stepping ring and I'm going to try that. I figured out how to get the aperture to open without mounting it, but aside from taping the controlling arm in place I don't know how to stop it down?

Any suggestions on alternative setups are appreciated, I have next to no budget though. Thanks for any tips at all really!

[John_B]

Aberrant,
You can make the aperture smaller but it will be much harder if not impossible to focus on a subject. It can be done like this: have the lens mounted normal on your camera, set the f/stop you want (ex. f/8 ) then press the DOF preview button and while holding down the DOF preview button remove the lens from the camera. Now the lens will have its aperture at f/8.
But if you can save some $$ a set of extension tubes, close up filters or of course a macro lens would be easier.
Hope that helps :)