The
Hoya +7 macro set and the Hoya +10 do not appear to be a
good match for the S1. Though the center of the image
might be sharp, edges and corners show distortion, worsening
as focal length increases.
The
Canon 250D (+4) and Raynox DCR-250 gave the best results
with no visible CA and corner to corner
sharpness over a large range of focal lengths. Though
the Raynox vignettes slightly at full wide angle, it appears
to give results as good as the Canon 250D with more than double
the magnification at about half the cost.
Don't
be too concerned about the DCR-250 vignetting at full wide,
the mid focal lengths work best anyway - less barrel distortion,
and more distance between the camera and subject make the
subject easier to light.