The Sigma 18-200mm f/3.5-6.3 DC OS HSM II is a compact all-purpose zoom lens with a 11x zoom ratio, equipped with a 4-stop optical image stabilizer and HSM autofocus drive and dedicated for small-format DSRL cameras only (it cannot be used on full-format and film cameras).
Its optical scheme includes three aspherical lenses, two SLD lenses and one FLD lens with properties very close to fluorite. Super Multi-Coating.
Internal focusing eliminates the front lens rotation and enables a convenient use of a petal hood and polarized filters.
Autofocusing is not available on the Pentax ist * K100D. The OS is not available on Sony and Pentax cameras.