Hi Trisha, STM stands for 'stepping motor'. Canon introduced it for video fans to overcome the problem of jerky zoom action when using standard lenses. The optical quality is the same as the IS ll although some say it is slightly better. Of course the STM can be used for shooting stills also. PBked
The newer STM version of 18-55mm is much improved over the ll version. Larger manual focus ring, non-rotating front element, full time manual focus, 13 elements in 11 groups vs 11/9, large zoom ring, 7 rounded aperture blades vs 6. I got mine refurbished from B & H and find it quite acceptable.
Comments
STM stands for 'stepping motor'. Canon introduced it for video fans to overcome the problem of jerky zoom action when using standard lenses. The optical quality is the same as the IS ll although some say it is slightly better. Of course the STM can be used for shooting stills also.
PBked
Larger manual focus ring, non-rotating front element, full time manual focus, 13 elements in 11 groups vs 11/9, large zoom ring, 7 rounded aperture blades vs 6.
I got mine refurbished from B & H and find it quite acceptable.