It sounds like concentric circles with Stroke Weights equalling the difference in size between neighbouring circles.
1) Create a circle with the largest/smallest size and set the Stroke Weight to the desired difference in size between neighbouring circles;
2) Copy and Paste in Front (or back) and change the size to the other extreme (a number of times the Stroke Weight);
3) Object>Blend>Options, set the number of steps to the number of intermediate circles, Object>Blend>Make, and Object>Blend>Expand and ungroup if desired.
Or you may start with one circle as in 1) and then Copy and Paste in Front and increase the size by the Stroke Weight (you can do that through the Transform palette/panel by adding it to (or subtracting it from) the W or H value and pressing Ctrl/Cmd Enter, just add + (or -) at the end in the box and then the amount; this may be repeated till you have enough.
I would draw the circles using the elipse tool: click on the tool, click on the document, enter the size circle you want (let's say 3 inches)
Then do the same thing over with equal increments (let's say 1/2 inch)
So you'll draw circles that are 3 inch, 2.5 inch, 2 inch, 1.5 inch, 1 inch, and .5 inch
Select all of the circles and use the align palette to center them horizontally & vertically
While all of the circles are selected, change the stroke to your desired width
Of course, the size/increment you choose will have to be relevant to how many "rings" you want on the finished piece.
you can do it that way probably the recommended way or you can just add new strokes to a circle and give the strokes offsets. The advantage to this method is you can add strokes and remove them and you can turn them on and off one at a time or several or all of them and you can have different colors or all the same color without destroying the art.
CS 4 has the ability to turn on and off any effect or stroke or fill.
How did you calculate the correct numbers for each offset amount?
The first ellipse (bullseye) is say 72 pts (1 inch) with a white stroke of half that 36 pts (1/2 inch) I then align the white stroke to the outside of the ellipse path.
Then I add a new stroke and make it black and align it to the outside of the path
and give it an offset of !/2 inch (36 pts) which is the weight of the first stroke align with the inside of the stroke touching the path. That is the stroke is align on the outside of the path. Sounds confusing but if you think about it is not.
So we now have a solid black core a white ring and a black ring.
Add another stroke align it to the outside of the path (the preview will look like it is not working but it is working) and this time give it an offset of 1 inch.
It will look like you have the same three original rings unless you put a color object behind.
now add another stroke and give it a color of black and align that to the outside of the path
Now give that an offset of 1.5 inches (108 pts) and you will now see the new black ring and the previously white ring you made.
And you keep adding a stroke align to outside and add a half inch to the previous offset.
And you can go crazy with the colors. And it is all one path.
Thanks for the explanation, Wade!
But it is possible this might not suit the OP at this stage of the game for them.
I am curious as to what they mark as an answer that serves their purposes, I think that it is important that the user relate to the technique.
I woud think one of the two previous approaches might suit them.
1. Polar Grid tool: Click (don't drag).
2. In the resulting dialog, enter the desired diameter for both width and height. Concentric dividers: 5. Radial dividers: 0. Skew: 0. Turn on the Make Compound Path from Concentric Dividers checkbox. Turn on the Fill Grid checkbox.
3. Click OK.
Wow! JETalmage. That makes it easy. This is my choice for drawing a target